PREFACE

General Biology 1 is a reference material tailored especially for senior high

school students. This module is written in high hope that both students and
instructor will further deepen their appreciation of science, specifically
biological sciences.

This AdZU – SHS RIGHT Learning Kit for General Biology 1 - STM 123 is
aligned to the competencies of the K-12 Basic Education Curriculum set by the
Department of Education.

This module is designed interactively to cater the needs and enabled of the 21st
century education. The concepts are highlighted together with their real-life
applications. The applications are very important for the students to appreciate
the concepts well. This shows that biology is within and around us wherever we
go. Biology is not confined to the four corners of the lecture and laboratory
classrooms.

General Biology 1 is arranged in a progressing manner from the basic to the

complex. It begins with the discussion of the cell parts and functions, cell
division, cell modification, biomolecules, photosynthesis, and cellular
respiration. These concepts are in line with the requirements of the senior high
school grade levels of the K to 12 curriculum, which also includes the 21st
century skills, and the College Readiness Standards.

Another highlight of the module is the reflection. While it is true that the
concepts and applications are important, incorporating the reflections with the
current pandemic may improve students positive values, which will result to
students being a responsible member of different societal groups.

This RIGHT Learning Kit is collaboratively prepared by your General Biology 1

instructors from the Ateneo de Zamboanga University – Senior High School for
school year 2022-2023.

i
 TABLE OF CONTENTS
UNIT I - MATTER AND ITS PROPERTIES ……. 1
Lesson 1 Eukaryotic and Prokaryotic Cell ……. 1
Context ……. 1
Experience ……. 1
Prelection ……. 1
Concept Notes ……. 2
Guided Practice: Laboratory Activity on Microscopy
…….
and Comparing Prokaryotic and Eukaryotic Cells 15
Reflection-Action ……. 18
Evaluation ……. 19
Lesson 2 Cell Division ……. 21
Context ……. 21
Experience ……. 21
Prelection ……. 21
Concept Notes ……. 22
Independent Practice: Concept Mapping ……. 38
Reflection-Action ……. 39
Evaluation ……. 40
Lesson 3 Transport Mechanism ……. 41
Context ……. 41
Experience ……. 41
Prelection ……. 41
Concept Notes ……. 42
Guided Practice: Concept in a box ……. 52
Reflection-Action ……. 53
Evaluation ……. 54

ii
 TABLE OF CONTENTS
UNIT II – BIOLOGICAL MOLECULES ……. 57
Lesson 4 Biomolecules ……. 57
Context ……. 57
Experience ……. 57
Prelection ……. 57
Concept Notes ……. 58
Independent Practice: Table Completion ……. 79
Reflection-Action ……. 81
Evaluation ……. 82
UNIT III - ELECTRONIC TRANSPORT ……. 87
Lesson 5 Photosynthesis ……. 87
Context ……. 87
Experience ……. 87
Prelection ……. 87
Concept Notes ……. 88
Independent Practice: Table Completion ……. 96
Reflection-Action ……. 97
Evaluation ……. 98
Lesson 6 Cellular Respiration ……. 100
Context ……. 100
Experience ……. 100
Prelection ……. 100
Concept Notes ……. 101
Independent Practice: Table Completion ……. 112
Reflection-Action ……. 113
Evaluation ……. 114
REFERENCES ……. 115

iii
 COURSE OUTLINE
STM123: General Biology 1
S.Y. 2022-2023

Semester: First
Midterm/Final Term
Inclusive Dates: Content/ Topic
August 1-12 Eukaryotic and Prokaryotic Cell
August 15-26 Cell Division
August 29 – September 2 1st Summative Exam
September 5-16 Transport Mechanism
September 19-23 MIDTERM EXAM
September 26 - October 14 Biomolecules
October 17-28 Photosynthesis
October 31 – November 11 Cellular Respiration
November 14-18 FINAL EXAM

v
 UNIT I
THE CELL
Lesson 1: Eukaryotic and Prokaryotic Cell

CONTEXT
Learning Competency
At the end of the lesson, the learners can;
a. explain the postulates of the cell theory;
b. distinguish prokaryotic and eukaryotic cells based on the major and subcellular
organelles and their distinguishing features; and
c. describe some cell modifications that lead to adaptation to carry out specialized
functions (e.g., microvilli, root hair).
Values Integration: Compassion and Care for creation

EXPERIENCE
Prelection: K-W-L Chart

Directions: Kindly fill out the first two columns (What do you know about the topic? and
What do you want to know about the topic?)

What do you want to What knowledge do

What do you know What did you learn
know about the you still need to
about the topic? about the topic?
topic? know?

1
Concept Notes
Timeline of Cell Theory
Table 1.1 Timeline of the cell theory
Date Event
1665 Cell first observed

Robert Hooke, an English scientist, discovered a honeycomb-like structure in a

cork slice using a primitive compound microscope. He only saw cell walls as
this was dead tissue. He coined the term "cell" for these individual
compartments he saw.

1670 First living cells seen

Anton van Leeuwenhoek, a Dutch biologist, looks at pond water with a

microscope he made lenses for.

1683 Miniature animals

Anton van Leeuwenhoek made several more discoveries on a microscopic level,

eventually publishing a letter to the Royal Society in which he included detailed
drawings of what he saw. Among these was the first protozoa and bacteria
discovered.

1833 The center of the cell seen

Robert Brown, an English botanist, discovered the nucleus in plant cells.

1838 Basic building blocks

Matthias Jakob Schleiden, a German botanist, proposes that all plant tissues are
composed of cells, and that cells are the basic building blocks of all plants. This
statement was the first generalized statement about cells.

1839 Cell theory

Theodor Schwann, a German botanist reached the conclusion that not only
plants, but animal tissue as well is composed of cells. This ended debates that
plants and animals were fundamentally different in structure. He also pulled
together and organized previous statement on cells into one theory, which
states: 1 - Cells are organisms and all organisms consist of one or more cells 2 -
The cell is the basic unit of structure for all organisms

2
 1840 Where does life come from

Albrecht von Roelliker discovers that sperm and eggs are also cells.

1845 Basic unit of life

Carl Heinrich Braun reworks the cell theory, calling cells the basic unit of life.

1855 3rd part to the cell theory added

Rudolf Virchow, a German physiologist/physician/pathologist added the 3rd

part to the cell theory. The original is Greek, and states Omnis cellula e cellula.
This translates as all cells develop only from existing cells. Virchow was also
the first to propose that diseased cells come from healthy cells.

Cells are the basic units of structure and function of all living things. There are two major
divisions into which all cells fall, the prokaryotic and eukaryotic. Prokaryotic cells are
cells that lack a nucleus and membrane-bound organelles. Bacteria and related
microorganisms are prokaryotes. Eukaryotic cells are cells that contain a nucleus and
membrane-bound organelles. Organisms such as animals, plants, fungi, and protist are all
eukaryotes. In this laboratory activity, you will observe

PROKARYOTIC CELLS:
Cellular Organelles in Prokaryotic Cells

Figure 1.1 Bacterial Cell

Source: studyblue.com

3
Table 1.2 Parts and Function of Prokaryotic Cell
PARTS FUNCTION
Cell wall Protection, structural support and maintenance of cell shape
Separates cell from external environment; controls passage of
Plasma
organic molecules, ions, water, oxygen, and wastes into and out of
Membrane
the cell
Provides structure to cell; site of many metabolic reactions; medium
Cytoplasm
in which organelles are found
Nucleoid Location of DNA
Ribosomes Protein synthesis
Maintains cell’s shape, secures organelles in specific positions,
Cytoskeleton
allows cytoplasm and vesicles to move within the cell, and enables
unicellular organisms to move independently
Flagella/pili Cellular locomotion (some)

For bacterial and archaeal species, the cell membrane encloses a single compartment –
meaning the cell has few or no subdivisions delimited by internal membranes. The cell
membrane is also called the plasma membrane, which consist of phospholipid bilayer
and membrane proteins. Virtually, all bacteria and archaea also have a cell wall that
surrounds the cell membrane.

Figure 1.2 Gram-positive and gram-negative cell wall

Source: microbiologyinfo.com

4
Table 1.3 Gram-positive vs gram-negative cell wall
Gram-positive bacteria Gram-negative bacteria
Cell wall consists of several layers of Cell wall is composed of a single layer of
peptidoglycan. peptidoglycan surrounded by a membranous
structure called the outer membrane.

Retain the purple crystal violet dye Do not retain the crystal violet, the cell wall is
when subjected to the Gram-staining composed of a single layer of peptidoglycan
procedure), surrounded by a membranous structure called the
outer membrane.

Chromosomes are structures that

consist DNA complexed with
specific proteins. Prokaryotic
chromosomes are found in a
localized area of the cell but are
not separated from the rest of the
cytoplasm by a membrane. By
far, the most extensive internal
membranes observed in
prokaryotes are found in
photosynthetic species. Figure 1.3 Genetic Material of Prokaryotic Cell
Source: bioninja.com

Table 1.4 Plasmid DNA vs Chromosomal DNA

PLASMID DNA CHROMOSOMAL DNA
A small, circular double-stranded A molecule that carries the genetic
Definition DNA molecule that is distinct from a information in all cellular forms of
cell’s chromosomal DNA life
Genomic Not considered as genomic DNA as it A type of genomic DNA
DNA is a form of extra chromosomal DNA
Naturally occurs only in prokaryotes Occurs in both eukaryotic and
Occurrence
prokaryotic cells
Size Can be 1-200 kilo base pairs Typically, larger than plasmid DNA
Shape Circular Linear
Number of a particular type of DNA Number of copies of a particular
Number vary from 1 to thousand per cell chromosome per cell is determined
based on the species

5
 EUKARYOTIC CELLS:
Cellular Organelles in Eukaryotic Cells

Eukaryotic cells range from 10 to 100μm in diameter while prokaryotic cells vary from
about 1 to approximately 10μm in diameter. A second point is that eukaryotic cells contain
numerous internal membranes. The membrane-bound compartments found in eukaryotic
cells are called organelles. In effect, eukaryotic cells are compartmentalized.

Why is this important?

ü Compartmentalization allows incompatible chemical reactions to be separated. For
example, fatty acid synthesis takes place in one organelle; fatty acids are degraded and
recycled in a different organelle.
ü Groups of enzymes that work together can be clustered on internal membranes instead
of floating free in cytoplasm. For example, many of the plant pigments, enzymes, and
other molecules responsible for converting sunlight into chemical energy are arranged
side by side in an internal membrane. The clustering of these molecules increases the
efficiency of the reactions, because intermediary compounds have to diffuse shorter
distances.
ü Because organelles are membrane-bound containers, they are able to maintain high
concentrations of molecules that are needed for specific chemical reactions. As a result,
the reactions proceed efficiently.
ü Compartmentalization makes large size possible. The size of prokaryotic cell is thought
to be limited by the distance that molecules have to diffuse inside the cell. Because
eukaryotic cells are subdivided, the molecules required for specific chemical reactions
are often located within a given compartment and do not need to move long distances to
interact.

Figure 1.4 Eukaryotic Cell

Source: thinglink.com

6
Table 1.5 Parts and Function of the Eukaryotic Cell
PARTS FUNCTION
• Located inside nucleus and disappears when cell divides
Nucleolus
• Makes ribosomes that make proteins
NUCLEUS

Nuclear envelope Double membrane surrounding nucleus and contains nuclear pore
Nuclear pore Where materials enter and leave the nucleus
DNA is spread out and appears as CHROMATIN in non-dividing
Chromatin
cells
• Has ribosomes on its surface
Rough Endoplasmic • Proteins are made by ribosomes on ER surface
Reticulum • They are then threaded into the interior of the Rough ER to be
modified and transported
• Makes membrane lipids (steroids)
Smooth Endoplasmic • Regulates calcium (muscle cells)
Reticulum • Destroys toxic substances (Liver)

• Made of PROTEINS and rRNA

Ribosomes • “Protein factories” for cell
• Join amino acids to make proteins through protein synthesis

• Jelly-like substance enclosed by cell membrane

Cytoplasm • Provides a medium for chemical reactions to take place
• Have a shipping side (cis face) & a receiving side (trans face)
• Receive proteins made by RER
Golgi Apparatus • Transport vesicles with modified proteins pinch off the ends
• Modify, sort, & package molecules from RER for storage OR
transport out of cell

• Contain enzymes that oxidize certain molecules normally found in

the cell, notably fatty acids and amino acids.
Peroxisomes • Those oxidation reactions produce hydrogen peroxide, which is
the basis of the name peroxisome.
• H2O2 → H2O + O

• “Powerhouse” of the cell

• Generate cellular energy (ATP)
• More active cells like muscle cells have MORE mitochondria
Mitochondrion • Both plants & animal cells have mitochondria
• Site of CELLULAR RESPIRATION (burning glucose)
• Has its own DNA

7
 PARTS FUNCTION
• Contain digestive enzymes
• Break down food, bacteria, and worn out cell parts for cells
• Programmed for cell death (APOPTOSIS)
Lysosomes
• Lyse & release enzymes to break down & recycle cell parts)
• Cells take in food by phagocytosis
• Lysosomes digest the food & get rid of wastes
• Helps cell maintain cell shape
• Also help move organelles around
Cytoskeleton • Made of proteins
• Microfilaments are threadlike & made of ACTIN
• Microtubules are tube-like & made of TUBULIN
• Mediates the vesicular transport of cargo - e.g. hormones or
neurotransmitters - from an organelle to specific sites at the
Secretory Vesicles
cell membrane, where it docks and fuses to release its
content.
• Found only in animal cells
• Paired structures near nucleus
• Made of bundle of microtubules
Centrioles
• Appear during cell division forming mitotic spindle
• Help to pull chromosome pairs apart to opposite ends of the
cell
• Fluid filled sacks for storage
• Small or absent in animal cells
• Plant cells have a large Central Vacuole
Vacuole
• In plants, they store Cell Sap
• Includes storage of sugars, proteins, minerals, lipids, wastes,
salts, water, and enzymes
• Found outside of the cell membrane of plant cells
• Non-living layer
Cell wall
• Supports and protects cell
• Found in plants, fungi, & bacteria

8
 Figure 1.5 Venn Diagram of the organelles present in Animal and Plant Cell

CELL MODIFICATION THAT LEAD TO ADAPTATION

Kinds of Cell Modifications

a. Apical Modifications (top) = cell modification is found on the top surface of

the cell
b. Basal Modifications (bottom) = cell modification is found on the bottom
surface of the cell
c. Lateral Modifications (sides) = cell modification is found on the sides of the
cell

9
 APICAL MODIFICATIONS

Microvilli
§ Also called brush/striated border
§ Finger-like cytoplasmic extensions of the apical surface which increase surface area
for absorption
§ Numerous, often regularly arranged, and found in absorptive epithelia

Stereocilia
§ Long microvilli that function in increasing absorption
§ Non-motile
§ Found in sensory cells in ear and male reproductive tract
§ Does not have the true characteristics of the true cilia or flagella

Cilia
§ Motile, function in movement
§ Beats in a coordinated rhythmical wave-like movement of materials over the surface
§ Appear as short hair-like structures or projections
§ Each cilium is connected to a basal body and extends from the free surface
§ Core is composed of microtubules arranged in a specific manner
§ Can be found in the lining of the trachea (windpipe) or in the Fallopian tube

Flagella
§ Are also concerned with movement
§ Same axial structure with cilia but much longer
§ Present in tail of the spermatozoa

Figure 1.6 Structure of microvilli, stereo Figure 1.7 Different structures of flagella
cilia, and cilia Source: shutterstock.com/flagella
Source: mmegias.webs.uvigo.es

10
 BASAL MODIFICATIONS

Basal Infoldings
§ Often found in epithelium that are known to transport fluid (kidney)
§ Will often see mitochondria in the basal infoldings, suggests that active transport is
occurring
§ Very important in epithelial polarization and stability
§ Support the epithelium and also functions as a passive molecular sieve or ultrafilter
§ If basal lamina is destroyed (trauma, infections, burns), the epithelium will not be
repaired but substituted with a scar (connective tissue)

Figure 1.8 Structure of basal infoldings

Source: pre-med.jumedicine.com

Hemidesmosome
§ Protein filaments interlock with
filaments of the adjacent cell
which forms a dense intermediate
line between the cells
§ Found beneath the zonula
adherens
§ Cytoplasmic face is connected to
microfilaments extending into the
cytoplasm

Figure 1.9 Structure of hemidesmosome

Source: journals.plos.org

11
 LATERAL MODIFICATIONS

Tight junctions (Zonula occludens)

§ A band near the apical surface forms a seal, appearing to be fused
§ There is 15-20 nm space between epithelium cells
§ Tight junction occludes/separates the compartments

Adhering Junctions (Zonula Adherens)

§ The actin filaments which make up zonula adherens maintain integrity of the cell to
better bind
§ It is found just beneath the tight junction
§ Cytoplasmic face is linked to the actin cytoskeleton

Desmosome (Maculs Adherens)

§ Protein filaments interlock with filaments of the adjacent cell which forms a dense
intermediate line between the cells
§ Help to resist shearing forces and are found in simple and stratified squamous
epithelium

Gap Junctions
§ Connexons of one membrane aligns with connexion of adjacent membrane so that
hydrophilic material can be transported
§ It is important in cell communication
§ Adjacent cells are 2-3 nm apart

Figure 1.10 Structure of tight, adherens, desmosomes, and gap junctions

Source: learnatnoon.com/

12
 SPECIALIZED MODIFICATIONS

ü Nerve cells or neurons are very specialized cells of the nervous system. Since an
electrical signal needs to travel relatively long distances to parts of the body, nerve cells
have specialized structures called dendrites, which received an electrical signal from
another neuron, and axons, which transmit an electrical signal to another neuron.

Figure 1.11 Neurons

Source: training.seer.cancer.gov/

ü Muscle cells are made up primarily of a pair of special proteins called actin and myosin
which allows the muscle to contract.

Figure 1.12 Muscle Cell

Source: crossfitinvictus.com

ü Red blood cells are anucleate, and thus are produced from bone marrow, but contain large
amounts of hemoglobin to transport oxygen throughout the body.

Figure 1.13 Red blood cell

Source: biologydictionary.net

13
ü Sperm cells are haploid and contain a flagellum in order to swim through the vagina.

Figure 1.14 Sperm Cell

Source: vectorstock.com

ü Vacuoles are membrane-bound organelles that can be found in both animal and plant. In
plant cells, vacuole help maintain water balance. Sometimes a single vacuole can take up
most of the interior space of a plant cell.

Figure 1.14 Vacuole in Plant Cell

Source: quora.com

14
Guided/Independent Practice

GUIDED PRACTICE: Laboratory Activity on Microscopy and Comparing Prokaryotic and

Eukaryotic Cells

MICROSCOPY
Micro" refers to tiny, "scope" refers to view or look at. Microscopes are tools used to enlarge
images of small objects so as they can be studied. The compound light microscope is an
instrument containing two lenses, which magnifies, and a variety of knobs to resolve (focus)
the picture. Because it uses more than one lens, it is sometimes called the compound
microscope in addition to being referred to as being a light microscope. In this lab, we will
learn about the proper use and handling of the microscope
Materials:
- Compound microscope - ruler
- 3 different colored strings - magazine

Procedures:
Part I. Examining Microscope Parts and Functions
1. Identify the parts and functions of a compound light microscope.

15
Part II. WET MOUNT- observing the letter “e”
1. Cut out the letter “e” and place it on the slide face up.
2. Add a drop of water to the slide.
3. Place the cover slip on top of the “e” and add a drop of water at a 45-degree angle
and lower. Draw what is on the slide in Figure1.
4. Place the slide on the stage and view in low power (4x). Center the “e” in your
field of view. Draw what you see in Figure 2.
5. Move the slide to the left, what happens? Move the slide to the right, what
happens? Up? Down?
6. View the specimen in high power (10x). Use the fine adjustment only to focus.
7. Draw what you see in Figure 3

COMPARING PROKARYOTIC AND EUKARYOTIC CELLS

Cells are the basic units of structure and function of all living things. There are two major
divisions into which all cells fall, the prokaryotic and eukaryotic. Prokaryotic cells are
cells that lack a nucleus and membrane-bound organelles. Bacteria and related
microorganisms are prokaryotes. Eukaryotic cells are cells that contain a nucleus and
membrane-bound organelles. Organisms such as animals, plants, fungi, and protist are all
eukaryotes. In this laboratory activity, you will observe several cells to examine the
differences between prokaryotic and eukaryotic cells.

Materials:
- Compound microscope - iodine stain - hornwort
- Glass slide - medicine dropper - onion
- Cover slip - cutter - rhoeo leaf
- Methylene blue

Prepared slides: spirillum, volvox, spirulina, coccus, ulothrix, bacillus, cuboidal

tissue and squamous tissue

Procedures:
PART I. Examining Animal Cells and some Prepared Slides
1. Using the prepared slides take a microscope from the stockroom and place it about
10 centimeters from the edge of the laboratory table.
2. Carefully clean the eyepiece and objective lens with lens paper.
3. Place your prepared slide on the microscope stage so that it is centered over the
stage opening. Hold the slide in position with the stage clips.
4. Using the low-power objective lens, locate the cell(s) under the microscope. Turn
the coarse adjustment knob until the cell comes into focus.

16
PART II. Examining Plant Cells
1. Gather a thin slice/piece of whatever your specimen is. If your specimen is too
thick, then the coverslip will wobble on top of the sample like a seesaw.
2. Place one to two drops of water directly over the glass slide and carefully take a
piece of onion skin off the onion (It is a thin layer underneath an onion layer).
Place it flat in the drop of water on your slide.
3. Place the coverslip at a 45-degree angle (approximately), with one edge touching
the water drop, and let go.
4. Place one drop of stain on one edge of the coverslip, and the flat edge of a piece of
paper towel on the other edge of the coverslip. The paper towel will draw the water
out from under the coverslip, and the cohesion of the water will draw the stain
under the coverslip.
5. As soon as the stain has covered the area containing the specimen, you are
finished. The stain does not need to be under the entire coverslip. If the stain does
not cover the area needed, get a new piece of paper towel and add more stain until
it does.
6. Be sure to wipe off the excess stain with a paper towel, so you do not end up
staining the objective lenses.
7. You are now ready to place the slide on the microscope stage. Be sure to follow all
the instructions as to how to use the microscope.
8. When you have completed your drawings, be sure to wash and dry both the slide
and the coverslip and return them to the correct places!
9. In a similar process as in procedure no.1, obtain a thin bottom layer of the rhoeo
leaf, then place it in a glass slide, then cover with a glass slip, then observe under
the microscope on both the low and the high-power objectives. Take note of the
color of the pigments you see in the leaf cell.
10.In a similar manner, observe a leaf sample of a hornwort under the microscope on
both low and high-power objectives as well. Do take note of the leaf’s pigment
color.

PART III. Examining Hay Infusion

1. Using a dropper, get small water samples from the top of the water, the bottom of
the jar, and near the floating debris in the middle. Using samples from all of these
areas will give you the best chance of getting different types of microbes for
viewing.
2. Observe the samples and look for protozoans. Capture images/videos of your
protozoans

17
REFLECTION-ACTION
Directions: Kindly complete the table by filling out the last two columns (What did you learn
about the topic? and What knowledge do you still need to know?)

What do you want to What knowledge do

What do you know What did you learn
know about the you still need to
about the topic? about the topic?
topic? know?

How will you be able to apply the knowledge you gained about how cells work in your day-
to-day life?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

All Eukaryotic organisms are composed of multiple organelles that are unique to each other
and perform different functions but work together to maintain and sustain life. How would
you encourage your classmates or friends to appreciate their uniqueness as senior high school
students?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

18
EVALUATION

CELL 3D MODEL

To create a 3D model of either animal cell, plant cell, or bacterial cell

GOAL
using recyclable materials
A Grade 12 STEM student of Ateneo de Zamboanga University who went
ROLE
on an immersion

AUDIENCE Students from far -flung area of Zamboanga City

The Grade 12 STEM students of Ateneo de Zamboanga University went on

an immersion to one of the far-flung areas in Zamboanga City to conduct
SITUATION tutorials to the students of the chosen barangay. With the limited facilities
and resources, the students of AdZU-SHS made an initiative to come up
with a 3D model of the cell to clearly illustrate its parts.

3D model of either animal cell, plant cell, or bacterial cell using recyclable
PRODUCT
materials
You will be graded based on the following standards: Clarity, Details,
STANDARD
Construction – Use of Indigenous Materials, and Timeliness

19
 CELL 3D MODEL RUBRIC

5 4 3 2
Cell model Cell model Cell model Model is a
clearly represents either somehow replica of a
Clarity
represents either animal, plant, or represents either generalized cell
(x1)
animal, plant, or bacterial cell animal, plant, or
bacterial cell bacterial cell
All organelles Most organelles More detail Parts of cells
and cell parts and cell parts are needed to are difficult to
are accurately accurately detailed recognize cell recognize and
detailed and and clearly parts. Some are numbers of
Details clearly recognizable. not recognizable. organelles are
(x2) represents the Actual numbers of Numbers of not
actual numbers organelles are organelles are representative
of organelles represented somewhat of an actual cell
representative of
an actual cell
Appropriate Appropriate Appropriate Inappropriate
materials were materials were materials were
materials were
Constructi
selected and selected and there selected selected and
on – Use of
creatively was an attempt at contributed to a
Indigenous
modified in creative product that
Materials
ways that made modification to performed
(x2)
them even make them even poorly
better better
Output was Output was Output was Output was
Timeliness submitted submitted hours or a submitted 2 days submitted 3 days
(x1) before/on the due day after the due after the due date. after the due date
date.
date.

20
Lesson 2: Cell Division

CONTEXT
Learning Competency
At the end of the lesson, the learners can;
a. describe the stages of mitosis/meiosis and their control points given 2n=6;
b. discuss crossing over and recombination in meiosis; and
c. explain the significance in the given disorders and diseases that results from the
malfunction of the cell during the cell cycle.
Values Integration: Care for creation and Respect for life

EXPERIENCE
Prelection: Two-minute Talk

Instruction: Look for a pair. With your partner, discuss the question that will be asked by your
instructor. A stopwatch or other timing device will be used to time the discussion for 2
minutes. After 2 minutes, look for another partner to discuss the answer to the same question.
Randomly, someone from the class will be called to share their discussions.

Question: Why do cells divide?

21
Concept Notes

CELL DIVISION: Mitosis and Meiosis

The continuity of life, from one cell to another has its foundation in the production of cells
by way of the cell cycle. The cell cycle is an orderly sequence of events that describes the
stages of a cell’s life from the division of a single parent cell to the production of two new
daughter cells. The mechanisms involved in the cell cycle are highly regulated.
MITOSIS is the part of a cell cycle that results in identical daughter nuclei that are also
genetically identical to the original parent nucleus. In mitosis, both the parent and the
daughter nuclei are the same ploidy level – diploid for most plants and animals.
MEIOSIS employs many of the same mechanisms as mitosis. However, the starting nucleus
is always diploid and the nuclei that result at the end of a meiotic cell division are haploid.

Figure 2.1 Mitosis vs Meiosis

Source: www2.le.ac.uk

22
Table 2.1 Difference between Mitosis and Meiosis Cell Division
MITOSIS MEIOSIS
Number of division 1 2
Number of daughter cells 2 4
Genetically identical YES NO
Same as parent Half of parent
Chromosomes #
(Diploid) (Haploid)
Somatic Cells Sex Cells
Where
(Body cells) (Reproductive cells)
When Throughout life At sexual maturity
Role Growth and repair Sexual reproduction

Figure 2.2 Mitosis vs Meiosis

Source: researchgate.net

23
 THE CELL CYCLE:
Mitosis

The cell cycle is an ordered series of events involving cell growth and cell division that
produces two new daughter cells. Cells on the path to cell division proceed through a series
of precisely timed and carefully regulated stages of growth, DNA replication, and cell
division that produces two identical (clone) cells.
The cell cycle has two major phases: INTERPHASE and the MITOTIC PHASE.
ü During interphase, the cell grows and DNA is replicated.
ü During the mitotic phase, the replicated DNA and cytoplasmic contents are separated,
and the cell divides.

Figure 2.3 Mitosis vs Meiosis

Source: www2.le.ac.uk

24
During interphase, the cell undergoes normal growth processes while also preparing for cell
division. In order for a cell to move from interphase into the mitotic phase, many internal
and external conditions must be met. The three stages of interphase are called G1, S, and G2.

Eukaryotic cell cycle is divided into 2 major phases:

1. Interphase
a. Divided into 3 stages – G1, G2, S
b. DNA Uncondensed

2. Mitotic Phase
a. 4 stages + Cytokinesis
b. Prophase, Metaphase, Anaphase, Telophase, Cytokinesis (PMAT)
c. Nuclear division & division of cytoplasm
d. DNA condensed

Three stages of interphase

1. Gap 1 (G1) Phase
a. Cell grows in size
b. Organelles are replicated

2. Synthesis (S) Phase

a. Replication of DNA
b. Synthesis of proteins associated with DNA

3. Gap 2 (G2) Phase

a. Synthesis of proteins associated with mitosis
b. Double checks the replicated chromosomes
c. Repairs error

Figure 2.4 Phases of cell division

Source: openoregon.pressbooks.pub

25
Cyclins regulate the cell cycle only when they are tightly bound to Cdks. To be fully active,
the Cdk/cyclin complex must also be phosphorylated in specific locations. Like all kinases,
Cdks are enzymes (kinases) that phosphorylate other proteins.

CDKs (Cyclin-dependent kinase)

– a family of protein kinases that are involved in regulating transcription, mRNA
processing, and the differentiation of nerve cells

Cyclins
– a group of proteins that control the progression of cells through the cell cycle by
activating cyclin-dependent kinase (CDK) enzymes

Figure 2.5 Cell cycle checkpoints

Source: openoregon.pressbooks.pub

STAGES OF MITOTIC PHASE

Karyokinesis, also known as mitosis, is divided into a series of phases – prophase,
prometaphase, metaphase, anaphase, and telophase – that result in the division of the cell
nucleus.

Figure 2.6 Stages of mitotic phase

Source: www2.le.ac.uk

26
Prophase
§ Chromosomes condense
§ Spindle fibers form (spindle fibers are specialized microtubules radiating out from
centrioles)
§ Chromosomes are captured by spindle

Figure 2.7 Prophase stage

Source: www.sparknotes.com

Prometaphase
#
" The mitotic spindle continues to develop as more microtubules assemble and stretch
across the length of the former nuclear area.
#
" Chromosomes become more condensed and discrete. Each sister chromatid develops
a protein structure called kinetochore in the centromeric region.

Figure 2.8 Prometaphase stage

Source: courses.lumenlearning.com

Metaphase
#
" All chromosomes are aligned in a plane called the metaphase plate, or the
equatorial plane. Midway between the two poles of the cell.
#
" The sister chromatids are still tightly attached to each other by cohesin proteins. At
this time, the chromosomes are maximally condensed.

Figure 2.9 Metaphase stage

Source: Source: courses.lumenlearning.com

27
Anaphase
§ Sister chromatids separate
§ Spindle fibers attached to kinetochores shorten and pull chromatids towards the poles.
§ Free spindle fibers lengthen and push poles of cell apart

Figure 2.10 Anaphase stage

Source: courses.lumenlearning.com

Telophase
§ Spindle fibers disintegrate
§ Nuclear envelopes form around both
groups of chromosomes
§ Chromosomes revert to their extended
state
§ Cytokinesis occurs, enclosing each
daughter nucleus into a separate cell
Figure 2.11 Telophase stage
Source: courses.lumenlearning.com

Cytokinesis
§ Cytokinesis, or “cell motion,” is the second main stage of the mitotic phase during
which cell division is completed via the physical separation of the cytoplasm
components into two daughter cells.
§ Animal cells undergo cytokinesis through the formation of a cleavage furrow. A ring
of microtubules contract, pinching the cell in half.
§ Plant cells undergo cytokinesis by forming a cell plate between the two daughter
nuclei.

Figure 2.12 Cytokinesis

Source: differencebetween.com

28
 Figure 2.13 Summary of Mitotic Cell Division
Source: courses.lumenlearning.com

UNCONTROLLED MITOSIS

Cancer caused by uncontrolled cell division. Cancer cells form disorganized clumps are
called tumors. Tumors can be benign or malignant.
§ Benign tumors remain clustered and can be removed
§ Malignant tumors metastasize, or break away, and can form more tumors

Oncogenes are special proteins that

increase the chance that a normal cell
develops into a tumor cell.
Oncology is the study of cancer
Cell checkpoints are times when the
cell is supposed to stop and check
itself, these are DISABLED in cancer
cells.

Figure 2.14 Uncontrolled Mitosis

Source: slideplayer.com

29
Tumor suppressor genes
Tumor suppressor genes are normal genes that slow down cell division, repair DNA
mistakes, or tell cells when to die (a process known as apoptosis or programmed cell death).
When tumor suppressor genes don't work properly, cells can grow out of control, which can
lead to cancer

Table 2.2 List of tumor suppressor genes

Figure 2.15 Illustration of cancer cell travelling through the bloodstream

Source: slideplayer.com

30
 THE CELL CYCLE:
Meiosis

Sexual reproduction requires fertilization, the union of two cells from two individual
organisms. If those two cells each contain one set of chromosomes, then the resulting cell
contains two sets of chromosomes. Haploid cells contain one set of chromosomes. Cells
containing two sets of chromosomes are called diploid. The number of sets of chromosomes
in a cell is called ploidy level.

Figure 2.16 Union of two cells from two individual organisms

Source: courses.lumenlearning.com

#
" If the reproductive cycle is to continue, then the diploid cell must somehow reduce
its number of chromosome sets before fertilization can occur again, or there will be a
continual doubling in number of chromosome sets in every generation. So, in
addition to fertilization, sexual reproduction includes a nuclear division that reduces
the number of chromosome sets. A single cell divides into four unique daughter
cells.
#
" Daughter cells have half the # of chromosomes as parent cell, so they are considered
haploid.

31
Ploidy - Refers to the number of sets of chromosomes in cells.
§ Haploid - one copy of each chromosome
- designated as “n”, the number of chromosomes in one “set”
- gametes

§ Diploid - two sets of chromosomes

- two of each chromosome
- designated as “2n”
- somatic cells
- organisms receive one of each type of chromosome from female parent
(maternal chromosomes) and one of each type of chromosome from male
parent (paternal chromosomes)

Figure 2.17 Difference between haploid and diploid chromosomes

Source: courses.lumenlearning.com

Homologues = Chromosomes exist in homologous pairs in diploid (2n) cells.

Exception: Sex chromosomes (X, Y).
Other chromosomes, known as autosomes, have homologues.

Autosomes = An autosome is any of the numbered chromosomes, as opposed to the sex

chromosomes. Humans have 22 pairs of autosomes and one pair of sex chromosomes (the X
and Y).

Figure 2.18 Autosomes and sex chromosomes

Source: differencebetween.com

32
At fertilization, 23 chromosomes are donated by each parent.
Total = 46 or 23 pairs

Gametes (sperm/ova):
§ Contain 22 autosomes and 1 sex chromosome.
§ Are haploid (haploid number “n” = 23 in humans)

Fertilization results in diploid zygote.

§ Diploid cell; 2n = 46. (n = 23 in humans)

STAGES OF MEIOSIS PHASE

Figure 2.19 Stages of Meiosis

Source: microbenotes.com

Table 2.3 Different events between Meiosis I and Meiosis II

MEIOSIS I MEIOSIS II
Synapsis occur No synapsis
Crossing over occurs No crossing over
In Metaphase I, paired homologous In Metaphase II, sister chromatids line up
chromosomes line up at equator at equator
In Anaphase I, paired homologous In Anaphase II, sister chromatids separate
chromosomes separate and move to and move to opposite poles
opposite poles
At the end of the Meiosis I, 2 haploid cells At the end of Meiosis II, 4 haploid cells
are formed are formed

33
 MEIOSIS I

During DNA duplication in the S phase, each chromosome is replicated to produce two
identical copies, called sister chromatids, that are held together at the centromere by
cohesin proteins. Cohesin hold the chromatids together until anaphase II. The centrosomes,
which are the structures that organize the microtubules of the meiotic spindle, also replicate.
This prepares the cell to enter prophase I, the first meiotic phase.

Prophase I
§ Chromosomes condense, and the nuclear envelope
fragments. Homologous chromosomes bind firmly
together along their length, forming a tetrad.
Chiasmata form between non-sister chromatids.
Crossing over occurs at the chiasmata. Spindle fibers
emerge from the centrosomes.
Figure 2.20 Prophase I
Source: microbenotes.com

Prometaphase I
#
" Homologous chromosomes are attached to spindle
microtubules at the fused kinetochore shared by the
sister chromatids. Chromosomes continue to
condense, and the nuclear envelope completely
disappears.

Figure 2.21 Prometaphase I

Source: microbenotes.com

Metaphase I
#
" Homologous chromosomes are attached to spindle
microtubules at the fused kinetochore shared by the
sister chromatids. Chromosomes continue to
condense, and the nuclear envelope completely
disappears.

Figure 2.22 Metaphase I

Source: microbenotes.com

34
Anaphase I
§ Spindle microtubules pull the homologous
chromosomes apart. The sister chromatids are still
attached at the centromere.

Figure 2.23 Anaphase I

Source: microbenotes.com
Telophase I and Cytokinesis
§ The nuclear membrane begins to form around the
daughter nuclei. Each daughter nucleus contains two
sister chromatids for each chromosome attached to a
common centromere. Because of crossing over, the
two sister chromatids are not identical.
§ Cytokinesis. When the cleavage furrow begins to
form, this marks the start of cytokinesis (cell
division). The resulting daughter cells are haploid
Figure 2.24 Telophase I and
(1N).
Cytokinesis I
Source: microbenotes.com

MEIOSIS II

During meiosis II, the sister chromatids within the two daughter cells separate, forming
four new haploid gametes. The mechanics of meiosis II is similar to mitosis, except that
each dividing cell has only one set of homologous chromosomes. Therefore, each cell has
half the number of sister chromatids to separate out as a diploid cell undergoing mitosis.

Prophase II
§ Sister Chromatids condense. A new spindle begins to form. The nuclear envelope starts
to fragment.

Prometaphase II
§ The nuclear envelope disappears, and the spindle fibers engage the individual
kinetochores on the sister chromatids.

Metaphase II
§ The sister chromatids are maximally condensed and aligned at the equator of the cell.

Anaphase II
§ The sister chromatids are pulled apart by the kinetochore microtubules and move toward
opposite poles. Non-kinetochore microtubules elongate the cell.

35
Telophase II and Cytokinesis
§ The chromosomes arrive at opposite poles and begin to decondense. Nuclear envelopes
form around the chromosomes. Cytokinesis separates the two cells into four unique
haploid cells. At this point, the newly formed nuclei are both haploid. The cells
produced are genetically unique because of the random assortment of paternal and
maternal homologs and because of the recombining of maternal and paternal segments
of chromosomes (with their sets of genes) that occurs during crossover.

Figure 2.25 Stages of Meiosis II

Source: sites.google.com

NONDISJUNCTIONS

§ Of all of the chromosomal disorders, abnormalities in chromosome number are the most
obviously identifiable from a karyogram.
§ Disorders of chromosome number include the duplication or loss of entire
chromosomes, as well as changes in the number of complete sets of chromosomes.
§ They are caused by nondisjunction, which occurs when pairs of homologous
chromosomes or sister chromatids fail to separate during meiosis.
§ Misaligned or incomplete synapsis, or a dysfunction of the spindle apparatus that
facilitates chromosome migration, can cause nondisjunction. The risk of nondisjunction
occurring increases with the age of the parents.
§ Nondisjunction can occur during either meiosis I or II, with differing results. If
homologous chromosomes fail to separate during meiosis I, the result is two gametes
that lack that particular chromosome and two gametes with two copies of the
chromosome.
§ If sister chromatids fail to separate during meiosis II, the result is one gamete that lacks
that chromosome, two normal gametes with one copy of the chromosome, and one
gamete with two copies of the chromosome.

36
Figure 2.26 Meiosis cell division causing nondisjunction
Source: sites.google.com

37
Guided/Independent Practice
INDEPENDENT PRACTICE: Concept Mapping
Directions: List down 3 differences and 5 similarities of mitosis and meiosis cell division.
You may use the information you have gathered in the Concept Notes. Share and compare
your concept map with a pair.

Differences

MEIOSIS
Similarities

MITOSIS
Differences

38
REFLECTION-ACTION
Modified SQ2R

Topic: Cell Division Date: _________________

Summary:
What are the different stages of cell cycle and cell division both for mitosis and meiosis?
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________

Factual Questions:
Write one question you still have in mind about cell division.
1. _____________________________________________________________________

Reflection:
In our society, cancer cells can be compared with fake news. Fake news has been spreading
uncontrollably over social media and many other platforms nowadays. It spreads several
misinformation towards a certain issue and leads to commotion online. and how will you
ensure that the information you post or share online are accurate?
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________

Real-life Application:
As a student and a social media enthusiast, how will you mitigate the spread of fake news?
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________

Writing to Learn Worksheet: Modified SQ3R

DEVELOPED BY ANITA R. TAGADIAD
2000

39
EVALUATION

A. Summative Exam: Kindly access your AdZU Eclass to take your 1st Summative Exam

B. Performance Task:
Perform an experiment on Cell Division and submit a Post
GOAL
Laboratory Report
ROLE You are Cytologist
AUDIENCE Farmers of Zamboanga City
Farmers of Zamboanga City have been struggling with the
slow growth of their crops and the abnormal growth of their
livestock. As an expert in the field of cytology, you study the
SITUATION cellular growth of the onion by investigating its root tip to
determine the problem on the crops and to explain how
mutation happens by studying the cell division among
chickens and cows.
PERFORMANCE/ Laboratory Experiment and Laboratory Report
PRODUCT
Please refer to the rubric for the grading of the Laboratory
STANDARD
Experiment

40
 Laboratory Experiment: Cell Cycle: Mitosis and Meiosis

The second cell division in Meiosis is known as Meiosis II. Meiosis II is very similar to
Mitosis. In both cases chromosomes line up and sister chromatids are separated by the
action of the spindle fibers. The daughter cells are genetically identical to one another.
There are some minor differences between Mitosis and Meiosis II. Cells at the start of
Mitosis II are haploid. Cells at the start of have the normal ploidy of the organism they are
in. Normally we think of Mitosis as occurring in diploid cells but in many organisms, it can
occur in haploid cells as well.

Materials:
- Compound microscope - prepared rooted onion bulb - alcohol lamp
- Glass slide - medicine dropper - cutter
- Cover slip - glacial acetic acid - coloring materials
- Paper towel - acetocarmine stain - pencil
- Ruler - 0.1M HCl

Prepared slides: Allum cepa, pollen, egg cell

Procedures:

PART I. Growing of Onion Root

1. Select a few medium-sized onion bulbs. Carefully remove the dry roots present.
2. Grow root tips by placing the bulbs on glass tubes (of about 3–4 cm. diameter)
filled with water
3. Care should be taken so that the stem portion of the bulb (basal part) just touches
the water
4. A few drops of water may be added periodically to compensate evaporation losses.
5. New roots may take 3–6 days to grow. Cut 2–3 cm long freshly grown roots and
transfer them to freshly prepared fixative, i.e., aceto-alcohol (1:3: glacial acetic acid
: ethanol).

PART II. Preparation of Slide

1. Take one or two preserved roots, wash them in water on a clean and grease free
slide
2. Place one drop of 0.1M HCl on the root tip followed by 2–3 drops of acetocarmine
or acetoorcein stain on it
3. Leave the slide for 5–10 minutes on a hot plate (or warm it slightly on spirit lamp).
Care should be taken that the stain is not dried up.
4. Carefully blot the excess stain using blotting paper. Now cut the comparatively
more stained (2–3 mm) tip portion of the root and retain it on the slide and discard
the remaining portion.
5. After (10–20 seconds) put one or two drops of water and blot them carefully using
blotting paper.

41
 6. Again put a drop of water on the root tip and mount a cover slip on it avoiding air
bubbles. Place the slide in between the folds of blotting paper using the fingers in
such a way that the cover slip mounted on the slide is properly held.
7. Now slowly tap the cover slip using the blunt end of a pencil so that the
meristematic tissue of the root tip below the cover slip is properly squashed and
spread as a thin layer of cells.
8. This preparation of onion root tips cells is now ready for the study of mitosis.
9. Place the slide on the stage of a good quality compound microscope. First observe it
under the lower magnification (10 X objective) to search for the area having a few
dividing cells. Examine the dividing cells under higher magnification of the
microscope to observe the detailed features of mitosis.
10.Compare the slide to the prepared slide Allum cepa.

PART III. Meiosis

Diagram the process of meiosis using the shapes provided below. Assume a diploid
number of 4. Label completely (Homologous Chromosomes, Crossing Over, Loci,
Centrosomes, Cleavage Furrow). Use the color pencils/crayons to draw
chromosomes (use one color for the parental chromosomes and another color for the
maternal chromosomes).

42
Lesson 3: Transport Mechanism

CONTEXT
Learning Competency
At the end of the lesson, the learners can;
a. relate the structure and composition of the cell membrane to its function;
b. explain transport mechanisms in cells (diffusion osmosis, facilitated transport, active
transport); and
c. differentiate exocytosis and endocytosis.
Values Integration: Compassion

EXPERIENCE
Prelection: My Personal Slam Book

Direction: Complete the short slam book below. Share your answer with your seatmate.

My Personal Slam Book

Name:

Favorite Perfume:

Favorite Drink/s:

Hobby:

43
Concept Notes
The plasma membrane, which is also called the cell membrane, has many functions but the
most basic one is to define the borders of the cell and keep the cell functional. The plasma
membrane is selectively permeable. This means that the membrane allows some materials to
freely enter or leave the cell, while other materials cannot move freely but require the use of
a specialized structure and, occasionally, even energy investment for crossing.

Figure 3.1 Structure of cell membrane

Source: www.khanacademy.org/

FLUID MOSAIC MODEL

The fluid mosaic model describes the arrangement of molecules that make up a cell
membrane.
The model is named due to two characteristics:
1. The cell membrane is flexible, not rigid
2. The other molecules in the cell membrane give its different patterns and textures
– like tiles in a mosaic

The fluid mosaic model describes the plasma membrane structure as a mosaic of
phospholipids, cholesterol, proteins, and carbohydrates.
Table 3.1 Components of a cell membrane
PARTS LOCATION AND FUNCTION
Phospholipid Main fabric of the membrane
Cholesterol Attached between phospholipid and between phospholipid layers
Integral Proteins Embedded between the phospholipid layer may or may not
penetrate through both layers
Peripheral Proteins On the inner or outer surface of the phospholipid bilayer; not
embedded within the phospholipids
Carbohydrates Generally attached to proteins on the membrane layer.

44
Selective permeability
§ A cell must exchange materials with its surroundings, a process controlled by the
plasma membrane
§ Plasma membranes are selectively permeable, regulating the cell’s molecular traffic
§ Hydrophobic molecules, such as hydrocarbons, can dissolve in the lipid bilayer and
pass through the membrane rapidly
§ Polar molecules, such as sugars, do not cross the membrane easily

Figure 3.2 Materials that can get in and out of the cell membrane
Source: www.dreamstime.com/

Table 3.2 Difference between passive and active transport

Passive transport Active transport
Allows molecules to pass the cell Pumps molecules through the cell
membrane through a concentration membrane against the concentration
gradient (high to low) gradient (low to high)
Diffusion, facilitated diffusion, and Endocytosis, exocytosis, secretion of
osmosis substances into bloodstream and
sodium/potassium pump
Does not require cellular energy Utilizes cellular energy in the form of ATP

Figure 3.3 Difference between passive and active transport

Source: Source: ib.bioninja.com.au

45
 PASSIVE TRANSPORT

The most direct forms of membrane transport are passive. Passive transport is a naturally
occurring phenomenon and does not require the cell to exert any of its energy to accomplish
the movement. In passive transport, substances move from an area of higher concentration
to an area of lower concentration. A physical space in which there is a range of
concentrations of a single substance is said to have a concentration gradient.

Types of passive transport

A. Simple diffusion
#
" Does not require energy to move molecules in and out of the cell.
#
" Example: Oxygen or water diffusing into a cell and carbon dioxide diffusing out
#
" Requires NO energy
#
" Molecules move from area of HIGH to LOW concentration
#
" Diffusion is a PASSIVE process which means no energy is used to make the
molecules move, they have a natural KINETIC ENERGY

Figure 3.4 Ink diffused in water

Source: Source: ib.bioninja.com.au

# Solute moves DOWN the concentration gradient. (HIGH to LOW)

"

Figure 3.5 Ink particles interacts with water molecules

Source: slideshare.net

46
B. Facilitated Diffusion
§ Molecules are too large or charged to diffuse on its own
§ Can diffuse if there is a specific transport protein (carrier or channel)
§ Does not require energy
§ Uses transport proteins to move high to low concentration
§ Examples: Glucose or amino acids moving from blood into a cell.

Channel Proteins are embedded in the

cell membrane & have a pore for
materials to cross
§ The integral proteins involved in
facilitated transport are collectively
referred to as transport proteins, and
they are transmembrane proteins.
§ Channels are specific for the substance
that is being transported.
Figure 3.6 Channel Proteins
Source: slideplayer.com

Carrier Proteins can change shape to

move material from one side of the
membrane to the other.
§ Some carrier proteins do not extend
through the membrane.
§ They bond and drag molecules through
the lipid bilayer and release them on the
opposite side.
§ The exact mechanism for the change of
shape is poorly understood. Proteins can
change shape when their hydrogen Figure 3.7 Carrier Proteins
bonds are affected, but this may not Source: labroots.com
fully explain this mechanism.

C. Osmosis
# Diffusion of water across a membrane
"
# Water is attracted to solutes (like salt) so it will also travel to areas of low solute
"
concentration to high solute concentration.
# Diffusion of WATER across a membrane
"
# Moves from HIGH water concentration to LOW water concentration
"
# Water is attracted to solutes (like salt) so it will also travel to areas of low solute
"
concentration to high solute concentration.

47
§ Tonicity describes how an extracellular solution can change the volume of a cell by
affecting osmosis. A solution’s tonicity often directly correlates with high osmolarity of
the solution.

§ Osmolarity describes the total solute concentration of the solution. A solution with low
osmolarity has a greater number of water molecules relative to the number of solute
particles; a solution with high osmolarity has fewer water molecules with respect to
solute particles.

Types of Osmosis:
ü Isotonic
─ A solution whose solute concentration is the same as the solute
concentration inside the cell.
─ The cell is at EQUILIBRIUM
─ Water will flow in BOTH DIRECTIONS outside and inside the cell.

ü Hypotonic
─ A solution whose solute concentration is lower than the solute
concentration inside a cell
─ The water is going INSIDE the cell.
─ Water is attracted to the solute inside the cell.

ü Hypertonic
─ A solution whose solute concentration is higher than the solute
concentration inside a cell.
─ The water is GOING OUT of the cell.

Figure 3.8 Osmosis in animal and plant cell

Source: www.tes.com

48
 Figure 3.9 Osmosis in red blood cell
Source: www.tes.com

ACTIVE TRANSPORT

Active transport mechanisms require the use of the cell’s energy, usually in the form of
adenosine triphosphate (ATP). If a substance must move into the cell against its
concentration gradient – that is, if the concentration of the substance inside the cell is
greater than its concentration in the extracellular fluid (and vice versa) – the cell must use
energy to move the substance.

Type of active transport

Sodium – Potassium Pump (Na+ - K+ Pump)
§ Pumping of ions against their concentration gradients which requires the addition
of energy from an outside source
§ 3 Na+ pumped out for every 2 K+ pumped in; creates a membrane potential.
§ In the kidneys the Na+ - K+ pump helps to maintain sodium and potassium balance
in our body. It also plays a key role in maintaining blood pressure and controls
cardiac contractions.
§ Failure of the Na+ - K+ pump can result in the swelling of the cell.

Figure 3.10 Sodium-potassium pump

Source: ib.bioninja.com.au

49
 BULK TRANSPORT

§ Endocytosis and exocytosis

§ Mechanism used in eukaryotes as this process requires energy which is known as active
transport
§ In addition to moving small ions and molecules through the membrane, cells also need
to remove and take in larger molecules and particles. Some cells are even capable of
engulfing entire unicellular microorganisms. The uptake and release of large particles
by the cell requires energy. A large particle, however, cannot pass through the
membrane, even with energy supplied by the cell.

Table 3.3 Endocytosis vs exocytosis

Endocytosis Exocytosis
Involved in the up taking of substances from Involved in the elimination of waste and
the external environment secretion of contents in Golgi into the
external environment
Occurs by both phagocytosis, pinocytosis Occurs by constitutive and regulated
and receptor-mediated endocytosis secretory pathway
Internal vesicles like phagosomes are Secretory vesicles are formed
formed
Example: engulfing bacteria by phagocytes Example: releasing of hormones out of the
cell

Figure 3.11 Illustration of endocytosis and exocytosis

Source: coursehero.com

50
Table 3.4 Types of endocytosis
Endocytosis
Phagocytosis Pinocytosis Receptor-mediated
§ Used to engulf large § Cell forms an § Some integral proteins
particles such as food, invagination have receptors on their
bacteria, etc. into § Materials dissolve in surface to recognize &
vesicles water to be brought into take in hormones,
§ Called “Cell Eating” cell cholesterol, etc.
§ Called “Cell Drinking”

Figure 3.12 Three types of endocytosis

Source: images.slideplayer.com

Exocytosis
#
" Type of active transport
#
" Moving things OUT
#
" Molecules are moved out of the cell by vesicles that fuse the with the plasma
membrane.
#
" This is how many hormones are secreted and how nerve cells communicate with
each other.

Figure 3.13 Process of exocytosis

Source: images.slideplayer.com

51
Guided/Independent Practice

GUIDED PRACTICE: Concepts in a box

Directions: In your respective groups, summarize the discussion on transport mechanisms by
creating a concept map or graphic organizer of how substances are transported in to and out
of the cell.

52
REFLECTION-ACTION
Modified SQ2R

Topic: Transport Mechanism Date: ____________________

Summary:
What are the two types of transport mechanism and how do they different from one
another?
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________

Factual Questions:
Write one question you still have in mind about transport mechanism.
1. _____________________________________________________________________

Reflection:
The entry and exit of the materials in and out of our cells are mediated by either passive or
active transport whether it can freely enter and exit the cell or with the help of the
transport proteins or receptors.
In maintaining the peace and order in every city in the Philippines during the fight against
COVID-19, soldiers were deployed to check every border to mitigate the entry and exit of
the people to prevent the spread of the virus. In your own point of view, what do you think
about the lighter restrictions in regards to the COVID-19 protocol in our city?
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________

Real-life Application:
What are the ways that you can help mitigate the transmission of the virus despite the
lighter restrictions?
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________

Writing to Learn Worksheet: Modified SQ3R

DEVELOPED BY ANITA R. TAGADIAD
2000

53
EVALUATION

A. Summative exam: Kindly access your AdZU Eclass to take your 2nd Summative Exam

B. Performance task:
Perform an experiment on Diffusion and Osmosis and submit
GOAL a Post Laboratory Report
You are Nephrologists who is responsible for your care during
ROLE dialysis treatments
AUDIENCE Students of AdZU School of Medicine
As one of the best Nephrologists in the city, you were asked to
give a talk about how diffusion and osmosis occurs in the
SITUATION kidney that may lead to complications. You have planned to
conduct an experiment to illustrate well how it works how
substances transport in and out of the cell.

PERFORMANCE/ Laboratory Experiment and Laboratory Report

PRODUCT
Please Refer to the rubric for the grading of the Laboratory
STANDARD Experiment

54
 Laboratory Experiment: Diffusion and Osmosis

Cells have an outer covering called the cell membrane. This membrane is selectively
permeable; it has tiny pores or holes that allow objects to move across it. The cell membrane
controls what moves in and out of the cell. Food and oxygen move into cells across the cell
membrane through the process of diffusion. Diffusion is movement of a substance from an
area of high concentration to an area of low concentration. Osmosis is a special type of
diffusion; it is the diffusion of water across a selectively permeable membrane. Osmosis
occurs when water moves from an area where it is more concentrated to an area where it is
less concentrated.

Materials

- 2 potatoes - 6 250 mL beakers - 1L Distilled water

- Cutter/ Cork borer - Stirring rod - Ruler
- 50 ml graduated cylinder - Triple beam balance - Timer
- 200 mL hot water - Liquid food coloring (any color)
- 200 mL cold water - 3 types of sugars (powdered, granulated, and rock)

Procedures:

PART I. Observing Factors Affecting Diffusion

1. Prepare 3 Beakers and label each with A, B, and C
2. Pour 150 mL of Hot water on beaker A, 150 ml of room temperature water in beaker
B, and 150 mL of cold water in beaker C.
3. Pour 2-3 drops of liquid food coloring in each of the beaker, then record the time it
takes for the food color to completely spread-out in the water setup.
4. Clean the beakers, then label them again as beakers A, B, and C.
5. 5.Pour 150 mL of room temperature water in each of the beaker.
6. Using the graduated cylinder, measure 5 grams of powdered sugar, 5 grams of
granulated sugar and 5 grams of rock sugar.
7. Pour the 5g powdered sugar in beaker A, 5g granulated sugar in beaker B, and 5g
rock sugar in beaker C.
8. Observe and record the time it takes for the sugar to dissolve on each setup.
9. Repeat procedure 4 and 5, then measure 5 grams, 10 grams and 15 grams of
granulated sugar respectively in the beam balance.
10.Pour in the 5 grams, 10 grams and 15 grams of granulated sugar to beakers A, B, and
C respectively.
11.Record and observe the time it takes for the sugar to dissolve in each of the beaker.

55
PART II. Preparing the Potatoes
1. Using your cutter or cork borer, prepare 18 strips of potatoes. Make sure to remove
the skin.
2. Using the ruler, even out the dimensions of the 18 potato strips and make sure they
are the same. The dimension should be 0.5 cm x 0.5 cm x 3 cm each.
3. One the potato strips are ready, get 6 beakers and transfer 3 pieces of strips in each.

PART III. Preparing the Salt Solutions

1. Using the beam balance, weigh- in 2 gram, 3 grams, 4 grams, 5 grams and 6 grams
of salt separately.
2. Transfer each weighted salt to each beaker setup, leaving 1 beaker with no salt.
3. Using the graduated cylinder, measure 100 mL of distilled water, then add to 1
beaker setup. Repeat the same process for the other setups. The beaker 1 with no salt
will be the controlled.

PART IV. Observing the setups

1. When all setups are ready, start the timer and leave it for 20 mins.
2. After 20 mins, remove the potato strips from the beaker and measure each strip 1
setup at a time.
3. Make sure to measure the potato strips as accurate as possible, to the nearest
millimeter as possible.
4. Note the measured value of the strips, then transfer them in the data sheet.

56
 UNIT II
BIOLOGICAL MOLECULES
Lesson 4: Biomolecules

CONTEXT
Learning Competency
At the end of the lesson, the learners can;
a. categorize the biological molecules (lipids carbohydrates proteins and nucleic acids)
according to their structure and functions;
b. explain the role of biological molecules in specific metabolic processes through
redox reaction;
c. describe the components of an enzyme; and
d. determine how factors such as ph, temperature, and substrate affect enzyme activity.
Values Integration: Competence

EXPERIENCE
Prelection: What’s the Fact?
Directions: For 1-2 mins let the students look and observe information in the nutritional fact
below.

Guide Questions:
1. What information can we get in the picture?
2. What do these pieces of information tell us?
3. Why do we need to take note of these pieces of information?

57
Concept Notes

General Properties of Biomolecules

Biomolecules are organic molecules, not fundamentally different from other, typical organic
molecules. They are the same types of molecules, react in the same ways, and obey the same
physical laws. Biomolecules contain mainly carbon (C), which behaves as it always does in
organic compounds, forming 4 bonds, usually with a tetrahedral arrangement. The carbon
skeleton can be linear, branched, cyclic, or aromatic. Other important elements are H, O, N,
P and S. many biomolecules are polyfunctional, containing two or more different functional
groups which can influence each other’s reactivity.

The majority of biomolecules have specific 3-dimensional shapes. The atoms of a

biomolecule are arranged in space in a precise way, and proper arrangement is usually
needed for proper function. The 3-dimensional shape is maintained by numerous non-
covalent bonds between atoms in the molecule. Because of the weak nature of most
noncovalent bonds and because of interactions between the biomolecule and the solvent, the
biomolecule’s structure is flexible rather than static.

TYPES OF BIOMOLECULES

Biomolecules can be divided into several major classes mainly as Nucleic Acids,
Carbohydrates, Lipids, and Proteins, which exhibit specific chemical properties and
characteristics.

1. NUCLEIC ACIDS

Nucleic acids are the most important biomolecules for the continuity of life. They carry the
genetic blueprint of a cell and carry instructions for the functioning cell.

Nucleic acids (DNA and RNA) are large polymers of nucleotides, with molecular weights
up into the billions. They form structures like the double helix, and they function in storing,
transmitting, and utilizing genetic information.

Nucleic acids are composed of nucleotides which possesses the following components – a
sugar, nitrogenous bases, and inorganic phosphate.

58
www.mun.ca

Components of Nucleotides:

A nucleotide is made up of three components: a nitrogenous base, a pentose sugar, and one
or more phosphate groups. The nitrogenous base is attached to the C1 of the pentose sugar
and the phosphate is attached to the C5. When a polynucleotide is formed, the C5 phosphate
of the incoming nucleotide attaches to the C3 hydroxyl group at the end of the growing
chain.

Figure 4.1 Three parts of nucleotide

Source: thoughtco.com

a. Sugars
There are only two types of sugars present in nucleic acids, ribose, which is
present solely in RNA (hence its name), and deoxyribose, which is present solely
in DNA (again, the sugar gave rise to the name deoxyribonucleic acid). The
chemical structures of these compounds are shown below:

Figure 4.2 Ribose and deoxyribose

Source: www.mun.ca

b. Bases
The nucleotide bases found in nucleic acids are related to the purine ring system
or the pyrimidine ring system. In the DNA, we find principally four different
bases: Adenine(A), Guanine (G), Cytosine (C), and Thymine (T). Adenine and
Thymine are purines, whereas Cytosine and Thymine are pyrimidines. In RNA,
we find principally four different bases as well, adenine, guanine and cytosine,
however, thymine is replaced with uracil (U).

59
The chemical structures for each of the five bases are shown below:

Figure 4.3 Purines vs pyramidine

Source: diffen.com

c. Inorganic Phosphate
There are phosphate residues in nucleic acids and they are of the type derived
from phosphoric acid, the structure of which is shown below.

Figure 4.4 Inorganic phosphate

Source: seekpng.com

When any of the bases is joined to either one of the two sugar molecules, we have a
compound known as nucleoside. If the sugar residue is ribose, then we have
ribonucleoside, whereas if deoxyribose, we have deoxyribonucleoside. The bond linking
these structures is known as a glycoside bond.

Addition of a phosphate group to the sugar residue nucleoside molecule produces a

different molecule called the nucleotide.

60
Formation of Nucleic Acid

Nucleic acids are formed by the combination of nucleotide molecules through sugar-
phosphate bonds known as phosphodiester linkages. Because nucleic acid is a polymer of
many nucleotide molecules, DNA and RNA molecules are called polynucleotides.

Figure 4.5 Nucleotide structure

Source: courses.lumenlearning.com

Difference between DNA and RNA

Table 4.1 DNA nucleotide vs RNA nucleotide

DNA Nucleotide RNA Nucleotide
Deoxyribonucleotide is the Ribonucleotide is the monomer
Definition monomer of DNA, that has od the RNA that has ribose as its
deoxyribose as its sugar residue sugar residue
Nucleic Acid Deoxyribonucleic acid Ribonucleic acid
Pentose Sugar Deoxyribose Ribose
Adenine(A), Guanine (G), Adenine(A), Guanine (G),
Nitrogenous Bases
Cytosine (C), and Thymine (T) Cytosine (C), and Uracil (U)
Adenine and Thymine pair (A-T), Adenine and Uracil pair (A-T),
Base Pairing and Cytosine and Guanine pair and Cytosine and Guanine pair
(C-G) (C-G)

Copies DNA code, transports

Stores genetic information and
Function amino acids and is used for
cellular instructions
protein synthesis.

61
2. CARBOHYDRATES

Carbohydrates are sugars and starches. They are the major source of energy in many
organisms, serve to store energy, and are structural components in some organisms. Because
of their wide distribution, carbohydrates are the most abundant type of biomolecule.

Formula and Structure of Carbohydrates:

Most carbohydrates have the general formula (CH2O)n. This suggested that they were
hydrates of carbon, hence the name. However, they are not hydrates of carbon, nor do all
carbohydrates conform to this formula. Carbohydrates are fundamentally polyhydroxy
aldehydes and ketones.

Types of Carbohydrates:
There are three major classes of carbohydrates based on size – monosaccharides,
disaccharides, and polysaccharides.

A. Monosaccharides are the simplest sugars, containing 3-7 carbons and one aldehyde or
ketone group.

Properties of Monosaccharides:
a. They are white solids, water-soluble (polar), and often have a sweet taste.
b. The formula is (CH2O)n where n = 3-7. The most common number of
carbons is 5 or 6.
c. The carbon skeleton is unbranched, connected by single bonds. One carbon
contains carbonyl oxygen (aldehyde or ketone). All other carbons contain a
hydroxyl group.
d. Monosaccharides are named with the suffix [-ose]. Every monosaccharide can
be classified as an aldose or ketose, depending upon the functional group.
e. They can also be classified according to the number of carbon atoms:
f. The two classifications are often combined, such as aldopentose or ketohexose.

Table 4.2 Types of sugars

No. of Carbon Type of Sugar Aldoses Ketoses

3 Trioses Glyceraldehyde Dihydroxyacetone
4 Tetrose Erythrose Erythrulose
5 Pentose Ribose, Xylose Ribulose, Xylulose
6 Hexose Glucose, Galactose Fructose
7 Heptose Glucoheptose Sedoheptulose

62
Structures of Common Hexoses:

Glucose
is the main sugar found in your
blood. It comes from the food you
eat, and is your body's main source
of energy. Your blood carries glucose
to all of your body's cells to use for
energy.

Figure 4.6 Glucose structure

Source: e-education.psu.edu

Galactose
is a monosaccharide sugar that is
about as sweet as glucose, and about
65% as sweet as sucrose. It is an
aldohexose and a C-4 epimer of
glucose. A galactose molecule linked
with a glucose molecule forms a
lactose molecule.

Figure 4.7 Galactose structure

Source: e-education.psu.edu

Fructose
is also known as “fruit sugar”
because it primarily occurs naturally
in many fruits. It also occurs
naturally in other plant foods such as
honey, sugar beets, sugar cane and
vegetables.

Figure 4.8 Fructose structure

Source: e-education.psu.edu

63
B. Disaccharides (two monosaccharides joined together). The bond that holds the
monosaccharides together is called a glycosidic bond. There are two basic
characteristics to any disaccharide. The first is the identity of the monosaccharide
components. These may be the same or different. The second is the nature of the
glycosidic bond. The bond is characterized by which carbons of the monosaccharides
are linked and by the orientation of the bond (α or β).

Examples of Disaccharides:

a. Maltose is a common disaccharide formed from the breakdown of plant and

animal polysaccharides. Its formula is C12H22O11, which is equivalent to 2
C6H12O6, showing water is lost when a glycosidic bond is formed.

Figure 4.9 Formation of maltose sugar

Source: shutterstock.com

b. Lactose is found in milk, forms D-glucose and D-galactose upon acid

hydrolysis. It has the molecular formula C₁₂H₂₂O₁₁. Lactose makes up around 2–
8% of milk.

Figure 4.10 Formation of lactose sugar

Source: commons.wikimedia.org

c. Sucrose- is formed by plants. Acid hydrolysis yields D-glucose and D-fructose.

It is non-reducing, so both anomeric carbons must be in the linkage (C-1 of
glucose and C-2 of fructose).

Figure 4.11 Formation of sucrose sugar

Source: courses.lumenlearning.com

64
C. Polysaccharides are very large, with hundreds or thousands of monosaccharide units
joined together. Polysaccharides, also known as glycans, have very high molecular
weights. Homopolysaccharides contain one type of monosaccharide unit.
Heteropolysaccharides contain two or more types of monomers. Polysaccharides do not
have definite molecular weights since enzymes easily add or remove monosaccharide
units.

A particular polysaccharide is characterized by its monomer types, the types of

glycosidic bonds present, and the degree of branching in the carbon chain.
Polysaccharides serve two main functions. First, they can serve as stores of metabolic
fuel (monosaccharides). Second, they can be structural or support elements of
organisms.

Examples of Polysaccharides:

a. Starch is the storage polysaccharide of plants, occurring as granules inside cells,

heavily hydrated with water. Starch has two components.

i. α-Amylose makes up ~20% of starch. It contains only D-glucose in an

unbranched chain with the units linked by α 1,4 glycosidic bonds.
Molecules have molecular weights of 150,000-600,000 which is about
1000-4000 glucose units.

Figure 4.12 Structure of amylose

Source: vivadifferences.com

ii. Amylopectin makes up 80% of starch. Molecules have molecular

weights up to 100 million. It contains only glucose, but the structure is
branched. Two types of glycosidic bonds are present, α 1,4 and α 1,6. Most
bonds are α 1,4. When an α 1,6 bond occurs the structure branches.

Figure 4.13 Structure of amylopectin

Source: vivadifferences.com

65
b. Glycogen is the storage polysaccharide of animals. It is very similar to
amylopectin, but more highly branched (every 8-12 residues) and more compact. It
is stored mainly in liver and skeletal muscle. Because it is branched, there are
many sites at which enzymes can degrade it, allowing glucose to be released
quickly when energy is needed.

Figure 4.14 Structure of glycogen

Source: toppr.com

c. Cellulose is found in the cell walls of plants where it provides support and
structure. It consists entirely of D-glucose in linear chains of 10,000-15,000
monomers. However, cellulose contains β 1,4 linkages which makes it quite
different from the earlier polysaccharides. Polysaccharide structure depends upon
the type of covalent glycosidic bonds. That structure then tends to be stabilized by
H-bonds between OH groups.

Figure 4.15 Structure of cellulose

Source: researchgate.net

d. Chitin forms the hard exoskeletons of arthropods (insects, lobsters, etc.). It is a

homopolysaccharide of N-acetyl-D-glucosamine joined by β 1,4 linkages. Thus, it
will form strong, extended fibers.

Figure 4.16 Structure of chitin

Source: sciencedirect.com

66
e. Peptidoglycan is a rigid envelope surrounding the cytoplasmic membrane of most
bacterial species. It helps protect bacterial cells from environmental stress and
helps preserve cell morphology throughout their life cycle. Peptidoglycan
biosynthesis is also an important regulator of bacterial cell division. It is composed
of glycan chains connected by short peptides; peptidoglycan forms a net-like
macromolecule around the cytoplasmic membrane.

Figure 4.17 Structure of peptidoglycan

Source: sciencedirect.com

67
3. LIPIDS

Lipids are fats and oils. They are water-insoluble substances that can be extracted from
cells using organic solvents. Because they are grouped based on solubility properties, they
are chemically more diverse than other groups of biomolecules. There are several distinct
classes of lipids. Most lipids function as energy storage molecules or as structural
components of membranes. Some are also hormones, vitamins, and pigments.

Types of Lipids
A. Fatty Acids
B. Triglycerides
C. Waxes
D. Glycerophospholipids

A. Fatty Acids
Fatty acids are carboxylic acids with hydrocarbon chains of 4 to 36 carbons with one
acid group. The chain usually contains an even number of carbon atoms, with 16 or 18
being the most common number. The chain is usually linear, but can be branched.

A few fatty acids contain three-carbon rings or hydroxyl groups. Some fatty acids are
saturated (no double bonds). Some are monounsaturated (one double bond) or
polyunsaturated (more than one double bond). For one double bond, the most common
position is between C-9 and C-10. For several double bonds, the most common
positions are C-9, C-12, and C-15. Double bonds are almost always unconjugated (-CH
= CH – CH2 – CH = CH -) rather than conjugated (- CH = CH – CH = CH -).
Saturated fatty acids are waxy solids while unsaturated fatty acids are oily liquids.

Free fatty acids are found in relatively low amounts in cells, but they are components
and building blocks of many types of lipids.

Figure 4.18 Structure of fatty acids

Source: quora.com

68
B. Triglycerides
Triglycerides (triacylglycerols) contain three fatty acids joined by ester bonds to a
glycerol molecule. The three fatty acids may be the same or different. Without the
-COOH group, they are even more non-polar than fatty acids. Triglycerides store
metabolic energy and provide insulation.

Figure 4.19 Structure of triglyceride

Source: study.com

C. Waxes
Waxes are esters of long-chain fatty acids (14-36 carbons) with long-chain alcohols
(16-30 carbons). Waxes function as metabolic fuels, and as protective coatings on hair,
feathers, plants, etc.

Figure 4.20 Structure of waxes

Source: ck12.org

D. Glycerophospholipids
Glycerophospholipids contain glycerol, two fatty acids, and a phosphate group at C-3
with a polar group attached to it. Usually C-1 has a saturated fatty acid attached and C-
2 has an unsaturated fatty acid. The groups that can attach to the phosphate include
ethanolamine, choline, serine, and glycerol. All glycerophospholipids always have a
negative charge on the phosphate. The polar group may have additional charges. Thus,
they are amphipathic with a polar head (phosphate) and non-polar tail (fatty acids).
They are found in cell membranes.

69
 Figure 4.21 Structure of glycerophospholipids
Source: nature.com

4. PROTEINS

Twenty percent of the human body is made up of proteins. Proteins are the large, complex
molecules that are critical for normal functioning of cells. • They are essential for the
structure, function, and regulation of the body’s tissues and organs. • Proteins are made up
of smaller units called amino acids, which are building blocks of proteins. They are
attached to one another by peptide bonds forming a long chain of proteins.

Amino Acid Structure

An amino acid contains both a carboxyl group and an amino group. Amino acids that
have an amino group bonded directly to the alpha-carbon are referred to as alpha
amino acids. Every alpha amino acid has a carbon atom, called an alpha carbon, Cα ;
bonded to a carboxylic acid, –COOH group; an amino, –NH2 group; a hydrogen atom;
and an R group that is unique for every amino acid.

Figure 4.22 Structure of amino acids

Source: examplespedia.com

70
Classifications of Amino Acids
There are 20 amino acids. Based on the nature of their ‘R’ group, they are classified based
on their polarity as:

Table 4.3 Classification of amino acids

Classification based on Essentiality

Essential amino acids are the amino acids which you need through your diet because your
body cannot make them. Whereas non-essential amino acids are the amino acids which are
not an essential part of your diet because they can be synthesized by your body.

Figure 4.23 Essential vs nonessential amino acids

Source: sproutliving.com

71
Peptide Bonding
Amino acids are linked together by ‘amide groups’ called peptide bonds. During protein
synthesis, the carboxyl group of amino acid at the end of the growing polypeptide chain
reacts with the amino group of an incoming amino acid, releasing a molecule of water. The
resulting bond between the amino acids is a peptide bond.

Figure 4.24 Peptide bond formation

Source: drawittoknowit.com

Structure of Proteins
§ The sequence of a protein is determined by the DNA of the gene that encodes the
protein (or that encodes a portion of the protein, for multisubunit proteins).
§ A change in the gene's DNA sequence may lead to a change in the amino acid
sequence of the protein. Even changing just one amino acid in a protein’s
sequence can affect the protein’s overall structure and function.
§ To understand how a protein gets its final shape or conformation, we need to
understand the four levels of protein structure: primary, secondary, tertiary, and
quaternary

a. Primary Structure
ü The simplest level of protein structure, primary structure is simply the
sequence of amino acids in a polypeptide chain.
ü The hormone insulin has two polypeptide chains A, and B. The sequence of
the A chain, and the sequence of the B chain can be considered as an
example for primary structure.

Figure 4.25 Protein primary structure

Source: commons.wikimedia.org

72
b. Secondary Structure
ü Secondary structure refers to local folded structures that form within a
polypeptide due to interactions between atoms.
ü The most common types of secondary structures are the α helix and the β
pleated sheet. Both structures are held in shape by hydrogen bonds, which
form between the carbonyl O of one amino acid and the amino H of another.

Figure 4.26 Protein secondary structure

Source: khanacademy.org

c. Tertiary Structure
ü The overall three-dimensional structure of a polypeptide is called its tertiary
structure. The tertiary structure is primarily due to interactions between the R
groups of the amino acids that make up the protein.
ü Important to tertiary structure are hydrophobic interactions, in which amino
acids with nonpolar, hydrophobic R groups cluster together on the inside of
the protein, leaving hydrophilic amino acids on the outside to interact with
surrounding water molecules.
ü Also, Disulfide bonds, covalent linkages between the sulfur containing side
chains of cysteines, are much stronger than the other types of bonds

Figure 4.27 Protein tertiary structure

Source: ib.bioninja.com.au

73
 d. Quaternary Structure
ü When multiple polypeptide chain subunits come together, then the protein
attains its quaternary structure.
ü An example for quaternary structure is hemoglobin. The hemoglobin carries
oxygen in the blood and is made up of four subunits, two each of the α and β
types.

Figure 4.28 Protein quaternary structure

Source: schoolworkhelper.net

Denaturation of Protein Folding

Each protein has its own unique shape. If the temperature or pH of a protein's environment
is changed, or if it is exposed to chemicals, these interactions may be disrupted, causing the
protein to lose its three-dimensional structure and turn back into an unstructured string of
amino acids.

When a protein loses its higher-order structure, but not its primary sequence, it is said to be
denatured. Denatured proteins are usually nonfunctional. Denaturation refers to the loss of
proper tertiary structure caused by breaking noncovalent bonds (but not covalent peptide
bonds) in a protein. Proteins can be denatured by heat, pH changes, and certain chemicals,
any of which will disrupt H-bonds, salt bridges, or hydrophobic interactions. To completely
denature a protein, any disulfide bonds must also be broken.

Figure 4.29 Protein denaturation

Source: pressbooks-dev.oer.hawaii.edu

74
ENZYMES

§ Enzymes are proteins whose main function is to helps speed up the processes in a
chemical reaction.
§ Enzymes allow reactions to occur under mild conditions, partly by eliminating
nonspecific side reactions.
§ They also participate in the reaction by providing an alternative reaction pathway. But
unlike other substances, they do not undergo permanent changes until the end of the
reaction.
§ They are only limited to changing the rate of reaction.

Parts of an Enzyme
ü Apoenzyme – Protein portion of such enzymes
ü Cofactor – Nonprotein component (e.g. magnesium, zinc) that often improve the
fit of an enzyme with its substrate
ü Holoenzyme – Nonprotein coenzyme or cofactor that is active when combined
with apoenzyme
ü Coenzyme – Nonprotein organic molecule bound to or loosely associated with
an enzyme (e.g. NADH, FADH)
ü Active site – The area on the enzyme surface where the enzyme forms a loose
association with the substrate
ü Substrate – the substance on which enzyme acts

Figure 4.30 Parts of enzyme

Source: slideshare.net

Enzyme- Substrate Complex

The reactants in an enzymatic reaction are called the substrates for that enzyme. To
illustrate this in a diagram, a substrate combines with an enzyme to form an enzyme-
substrate complex:

E (enzyme) + S (substrate) = ES (enzyme-substrate complex)

75
The common analogy used in illustrating an active site is the lock-and-key relationship. The
key can work perfectly when it exactly fits the lock.

However, there are times when certain adjustments are also done by the enzyme to achieve
an optimum fit for the substrates. This is called the induced fit theory. After the reaction is
completed, the product is released, and then the active site goes back to its original
condition, ready to bind with another substrate.

Figure 4.31 Parts of enzyme

Source: chem.libretexts.org

Factors Affecting Enzyme Activity

The rate of reaction is the amount of product that is produced per unit of time. There are
major factors that affect the catalytic function of enzymes – temperature, substrate
concentration, optimal pH, enzyme cofactors, and enzyme inhibitors.

a. Temperature
§ Each Type of enzyme has a temperature range at which it works best
§ Enzyme activity increases as the environment reaches that ideal
temperature. Activity slows down outside of that range.

Figure 4.32 Temperature affecting enzyme activity

Source: quora.com

76
b. Substrate Concentration
§ Enzyme activity increases with increasing substrate concentration
§ At a certain concentration, the enzyme will be saturated and operate at
maximum reaching its point of saturation

Figure 4.33 Substrate concentration affecting enzyme activity

Source: quizlet.com

c. Optimal pH
§ Enzymes have a specific pH range at which they will work
§ For most enzymes, the effective pH range is 4.0-9.0pH
§ Beyond these limits, denaturation of enzymes take place
§ Optimum pH for pepsin is 2.0 and 8.0 for trypsin

Figure 4.34 pH affecting enzyme activity

Source: otosection.com

d. Enzyme Cofactor and Inhibitors

§ Cofactor are substances that are essential to the catalytic activity of some
enzymes
§ Cofactor may alter the shape of enzymes slightly to make the active site
functional or to complete the reactive site
§ Many enzymes will not work unless they are accompanied by cofactors
or coenzymes

77
 § Enzyme inhibition is important in controlling enzymatic reactions
because once the body has completed the necessary chemical processed,
enzymatic reactions have to stop.

Figure 4.35 Inhibitors affecting enzyme activity

Source: khanacademy.org

Competitive and Noncompetitive Inhibitors

ü Competitive Inhibitor - Binds reversibly to the same site that the substrate binds –
competes with the substrate for binding
ü Noncompetitive Inhibitors - Binds at a site other than the active site of an enzyme and
changes the shape of the active site

Figure 4.36 Competitive and non-competitive inhibitors

Source: socratic.org

78
Guided/Independent Practice

INDEPENDENT PRACTICE: Table Completion

Direction: Complete the table below by filling out the information asked on each section.
Then answer the guide questions below.

Biological
Subunit
Biomolecule Function/s or Subunit/s Sources
Structure
Importance

Carbohydrates

Lipids/Fats

Proteins

Nucleic Acids

79
Further Questions:

1. What type of biomolecules are enzymes? Why do you say so?

_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________

2. What are the role of enzymes in the body?

_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________

3. What does it mean when an enzyme is denatured? Explain.

_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________

80
REFLECTION-ACTION

Modified SQ2R

Topic: _________________________________
Reference: ____________________________

Summary:
Explain the importance of each biomolecule to our body.
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________

Factual Questions:
Write one question you still have in mind about biological molecules.
1. _____________________________________________________________________

Reflection:
Enzymes are proteins that act as biological catalysts. Catalysts accelerate chemical
reactions. In life, we also need a catalyst to either motivate us or push us harder especially
at times of giving up. Personally, what or who do you consider as a catalyst in your life?
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________

Real-life Application:
Food is an essential commodity for our survival. Since the advent of farming in the human
history, food has become a readily available goods, that we often took for granted. Most
often the not, we are not mindful of the things that we eat which may lead to some
nutritional imbalances in our body. How do you make sure that the food you are eating is
well balanced? What are your considerations when you prepare/ buy food?
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________

Writing to Learn Worksheet: Modified SQ3R

DEVELOPED BY ANITA R. TAGADIAD
2000

81
EVALUATION

A. Summative exam: Kindly access your AdZU Eclass to take your 3rd Summative Exam

B. Performance task:

Perform an experiment on Biomolecules submit a Post

GOAL
Laboratory Report

ROLE You are Nutritionist

AUDIENCE Consumers of Zamboanga City

Many ordinary consumers do not have a clear idea on the
presence of macromolecules in the food products that they are
buying and will go blindly choose food items without
properly examining the nutritional fact labels. As an expert in
SITUATION
the field of nutrition, you are task to conduct a series of
experiments that will help determine the presence of
macromolecules on food items and identify which
macromolecule/s is/are present on them.
PERFORMANCE/
Laboratory Experiment and Laboratory Report
PRODUCT
Please Refer to the rubric for the grading of the Laboratory
STANDARD
Experiment

82
 Laboratory Experiment: Biomolecules and Enzyme

Four types of carbon-based biomolecules are found in living organisms: carbohydrates,

lipids, proteins and nucleic acids. Since foods consist of plant or animal materials, they are
combinations of these biomolecules, providing us with energy and building blocks
necessary for life (you really are what you eat!).

In this lab, you will test to see which biomolecules are found in common foods. You will
perform simple chemical tests with substances called indicators to detect the presence of
carbohydrates, proteins, and lipids in certain foods. (An indicator is a substance that
changes color when a certain compound is present.) Each simple test includes a positive
and negative control – water and a solution containing a pure sample of a specific
biomolecule.

Materials:
- 12 Test tubes - 4 marbles - Grater
- Triple beam balance - 1 test tube rack - Paper towel
- Masking tape - Yeast - 1 test tube brush
- Blotting paper - Dropper - dish soap
- Safety goggles - latex gloves - disposable mask -
graduated cylinder - Plastic bag (per class) - 1 hot water bath
- 4 200 mL beakers - warm water - cutter
- potato - measuring spoon - 25 mL vinegar
- ruler

Chemical reagents
- Iodine solution - Alpha Napthol Reagent
- Biuret solution - Concentrated Sulfuric Acid (H2SO4)
- Benedict’s solution - Ninhydrin solution
- 3% hydrogen peroxide

Food sample to test:

Group A Group B
-2 Eggs -2 Eggs
-Fresh Milk -Coconut Milk
-Potato -Apple

83
Procedures:

!!!TEST PROTOCOL!!!
1. Make sure you rinse your test tubes thoroughly after each test to avoid contamination.
2. Label the test tube using your masking tape
3. Safety googles, surgical mask and latex gloves must be used when dealing with
concentrated sulfuric acid

PART I. Test for the Presence of Carbohydrates: Molisch Test

SAFETY GOOGLES, SURGICAL MASK AND LATEX GLOVES MUST

BE USED WHEN DEALING WITHCONCENTRATED SULFURIC ACID

1. Add 1 ml dropper- full of each sample to a test tube. Note to separate the egg yolk
and egg white for a specific test tube.
2. Add 1 drop of alpha naphthol reagent in each test tube and mix thoroughly.
3. Then add 1 mL of concentrated H2SO4 in each test tube carefully by inclining the
tube and letting the sulfuric acid slide down on the side.

Positive test: The appearance of reddish violet or purple colored ring

🧑 at the junction of two liquids is observed in a positive Molisch test.

PART II. Test for the presence of Carbohydrates (Monosaccharide): Benedict’s Test
1. Add 1 ml- dropper- full of each sample to its own test tube.
2. Add 1 ml- dropper- full of Benedict’s solution to each of the test tube with the
food samples.
3. Place the test tubes in the hot water bath. Heat the test tubes for 5 full minutes.

Positive test: Benedict’s changes from blue to yellow or orange when

heated with the presence of monosaccharides.

🧑 Note: Sometimes this chemical reacts with another biomolecule to

form a blue or purple color. This is not the reaction that you are
looking for.

84
PART III. Test for the Presence of Carbohydrates (Polysaccharides): Lugol’s Test
1. Add 1 ml- dropper- full of each sample to its own test tube.
2. Add 2-3 drops of iodine to each sample, then shake.

Positive test: Lugol’s iodine changes from brown to blue or black with
🧑 the presence of starch

PART IV. Test for the presence of Lipids

1. Prepare 7 blotting papers or tear 7 small squares from a piece of brown paper or
paper bag. Label each with the name of the food sample.
2. Add a drop of each food sample on their respective blotting/ brown paper.
3. Set the paper aside to dry, for about 10 minutes.
4. After 10 minutes, hold the paper through a light and observe for translucent spots.

Positive test: A translucent spot on the paper indicates the presence of

🧑 lipids in the sample.

PART V. Test for the presence of Proteins (Generic Test for Proteins): Biuret Test
1. Add 10 drops of each food sample to its own test tube.
2. Add 5 drops of NaOH to the food sample and then mix carefully.
3. Then add 3 drops of 1% CuSO4. (Note: do not shake the mixture)

Positive test: Biuret is clear/blue in the absence of protein, and turns

🧑 purple with the presence of protein.

PART VI. Test for the presence of Proteins (Test for Proline): Ninhydrin Test
1. Add 2 mL of each food sample to its own test tube.
2. Add 10 drops of 0.1% ninhydrin solution in each test tube.
3. Cover the test tube with marble and heat it in a boiling water bath for 1-2 mins.
4. Remove from the water bath and allow to cool. Observe what happens.

Positive test: A positive test is either a purple/violet or a yellow color.

🧑 The yellow color indicates the presence of a specific amino acid
proline. The purple color indicates the presence of any other free
amino acid.

85
PART VII. Potato Enzyme Setup
1. With the guide of your ruler, cut a 1 cm wedge on your potato.
2. From the potato wedge, cut a 2 cm section, then from the 2 cm section, cut four
0.5 cm sections of potatoes.
3. You will end up having 4 pieces of potato sections with dimensions of 1cm x 2 cm
x 0.5 cm.
4. Note each potato as potato 1, 2, 3, and 4. Chop potato 3 into small tiny chunks. On
the other hand, put potato 2 in a boiling water in a hot plate for about 1-2 minutes.
5. After this, setup your 4 test tubes in your test tube rack, labeled as test tubes 1, 2,
3 and 4, corresponding to your 4 potatoes.
6. Add 2 ml of hydrogen peroxide to each of the test tubes. Afterwards, add 1 ml of
water to test tubes 1-3, while on test tube 4 add 1 ml of vinegar.
7. Put the potatoes in to your test tubes. Test tube 1 with the regular potato; test-tube
2, with the boiled potato; test tube 3, with the chopped potato; and test tube 4 the
other regular potato.
8. Let the setup sit for a few seconds and observe the fizzing action.
9. Record the time it takes for the fizzing to start, then using your ruler, measure the
fizz’ length in the test tube.
10.Record your data in the data sheet provided.

PART VIII. Yeast Setup

1. Dissolve 7 grams of dry yeast in 120 mL of warm tap water, then stir.
2. Get 4 clear plastic cups/ beakers, then label each as 1, 2, 3 and 4.
3. Add a teaspoon of dish washing soap on each of the cup.
4. To cup1, add 8 mL of hydrogen peroxide, 16 mL of hydrogen peroxide to cup 2,
then 24 mL in cup 3 and lastly, 32 mL to cup 4.
5. Gently swirl the cups until the dish soap has dissolved.
6. Then add 1 table spoon of yeast solution 1 cup at a time, and then observe what
happens to each cups for 15 minutes, in every 5 minutes interval.
7. Place all 4 cups next to each other and compare the size of the bubbles produced.
Transfer your observation/s on the date sheet provided.

86
 UNIT III
ENERGY TRANSPORT
Lesson 5: Photosynthesis

CONTEXT
Learning Competency
At the end of the lesson, the learners can;
a. explain coupled reaction processes and describe the role of atp in energy coupling
and transfer;
b. describe the major features and chemical events in photosynthesis and respiration;
c. explain the importance of chlorophyll and other pigments in the pattern of electron
flow through light reaction events; and
d. describe the significant events of the Calvin cycle.
Values Integration: Compassion and Empathy

EXPERIENCE
Prelection: K-W-L Chart

Directions: Fill in the 1st column (What you know about the topic) and 2nd column ( what I
wonder/unsure about the topic) of the table below.

What do you know about the What I Wonder/ unsure about What I Learn today about the
topic? the topic topic

87
Concept Notes
All of the oxygen we breathe, food we eat, and the fossil fuels we use are products of
photosynthesis. Photosynthesis is the process that converts energy in sunlight to chemical
forms of energy that can be used by living organisms. Photosynthesis is carried out by many
different organisms, ranging from plants to bacteria, with about 90% of the photosynthesis on
the planet occurring in the oceans. All of these organisms convert CO2 (carbon dioxide) from
the atmosphere to organic material (carbohydrates) in a complex set of reactions. The
carbohydrates produced are then used by the plants (or the animals that eat the plants) to
make all the "stuff" they need to live. Water is converted to oxygen and hydrogen using
energy provided by sunlight. The extra oxygen is released as a waste product and the
hydrogen is used to make the carbohydrate. (Remember, plants need some oxygen for
respiration).

The general equation for photosynthesis can be expressed as follows:

Figure 5.1 Photosynthesis equation

Source: quora.com

Photosynthesis occurs in eukaryotes plants, algae and certain types of prokaryotes, all of
which are described as autotrophs (literally self-feeder). Heterotrophs, "other-feeders,"
cannot synthesize their food from inorganic materials and therefore must obtain their organic
molecules by consuming autotrophs or other heterotrophs.

Energy Cycle
§ The producers are autotrophs (indicated by the tree here) that use the Sun's light as their
energy source, and they produce carbohydrates from inorganic compounds.
§ The primary consumers (indicated by the deer here) obtain their energy by eating the
producers.
§ Secondary consumers (indicated by the wolf here) obtain their energy from the primary
consumers.
§ Detritivores (indicated by the worm here) consume dead organisms and other wastes,
contributing to the recycling process, while decomposers (indicated by the mushroom
here) further break down the organic materials from dead cells and waste, freeing nutrients
for use by plants and completing the recycling process.

88
 Figure 5.2 Energy flow in ecosystem
Source: qsstudy.com

Carried out by photoautotrophs

§ Plants, phytoplankton, cyanobacteria ( any photosynthetic organism)

The basis of all ecosystems:

§ All “food energy” ultimately comes from the sun
§ Source of all atmospheric oxygen (O2)

89
 Leaf
It is the top section of the plant the whole
leaf looks green to us, the green color comes
from the chlorophyll molecules in the
chloroplasts.

Leaf section
On the top bottom are the cuticle layer and
the epidermal cell. In the middle between the
epidermis cell. On the bottom only, in most
plants, are the stomata which let carbon
dioxide in and oxygen out.

Mesophyll
The chloroplast where photosynthesis
occurs, are in the mesophyll cell.

Chloroplast
Each chloroplast is a little carbohydrate
factory powered by soar energy and for
which the only raw materials are carbon
dioxide, water and few minerals.

Granum
The little round flat pillow things are called
thylakoids. A stack of them is called granum
two more stack are called grana

Thylakoid
Thylakoid is also called the photosynthetic
membrane where photosynthesis start.

Figure 5.3 Parts of the leaf

Source: sciencefacts.net

90
Photosynthesis consists of 2 sets of Reaction

Photosynthesis consists of light-dependent and light-independent reactions these reactions

occurs in within a different region of the chloroplasts; the two are link by energy-carrier
molecules

§ Light-dependent Reactions
Convert light energy to chemical energy (ATP + NADPH) and produce oxygen gas
as a waste product

§ Light-independent Reactions (Calvin Cycle)

Make sugar using carbon dioxide and the energy-containing products of the light-
reactions (ATP + NADPH)

Figure 5.4 Summary of photosynthesis

Source: quizlet.com

One of three events occurs when light strikes an object such as leaf: the light is either
absorbed (captured), reflected (bounced back), or transmitted (passed or drive biological
processes, such as photosynthesis. Light that is reflected or transmitted reaches our eyes and
gives an object its color.

Chloroplasts contain other molecules, called accessory pigments, absorb additional

wavelengths of light energy and transfer it to chlorophyll a.

Chlorophyll a & b:
ü the major pigments (absorb red, blue…, reflect green)

Carotenoids (e.g., β-carotene)

ü accessory pigments (absorb green, blue, reflect red, yellow)

91
 Figure 5.5 Light absorption for photosynthesis
Source: ib.bioninja.com.au

THE LIGHT-DEPENDENT REACTIONS

The light-dependent reactions occur in the THYLAKOIDS. Light excites electrons in

chlorophyll molecules and transfers the energetic electron to electron transport chains. The
energy of these electrons drives three processes.

§ Photosystem II generates ATP. Some of the energy from the electrons is used to pump
hydrogen ions into the thylakoids. The hydrogen ion concentration is therefore higher
inside the thylakoids than in the stroma outside. Hydrogen ions move down the
concentration gradient through ATP synthesizing enzymes in the thylakoid membranes
providing the energy to drive ATP synthesis.

§ Photosystem I generates NADPH. Some of the energy in the form of the energetic
electron, is added to electron carrier molecules of NADP+ to make the highly energetic
carrier NADPH

§ Splitting water maintains the flow of electrons through the photosystems. Some of the
energy is used to split water, generating electrons, hydrogen ions, and oxygen.

Figure 5.6 Light-dependent reaction

Source: courses.lumenlearning.com

92
Four general steps of the light-dependent reactions

1. Water split to oxygen two atom of hydrogen and two high energy (e-) in PS II

H2O + sunlight → O2 + H+ + 2e-

2. Energy released by a series of e- transfers is used to generate H+ gradient. H+

accumulates inside the thylakoid membrane
3. H+ gradient used to make ATP ( chemiosmosis)
4. e- re- energized in PSI, passed on to NADP+
5. e- ends up NADPH ( an electron carrier)

Products of light - dependent reaction

To summarize the light reaction, we can write it down as the following reaction:

2H2O + 2NADP+ + 3ADP + 3Pi → O2 + 2NADPH + 3ATP

Figure 5.7 Products of light-dependent reaction

Source: toppr.com

93
 THE LIGHT-INDEPENDENT REACTIONS

Light-independent reaction happens in the STROMA of the chloroplast. This stage, as

opposed to the light-dependent reaction phase, can occur during both day and night. It is
NOT dependent on solar energy.

Figure 5.8 Light-independent reaction

Source: shmoop.com

How is chemical energy stored in Glucose Molecules?

In the stroma of the chloroplasts both ATP and NADPH provide the energy that drives the
synthesis of glucose from CO2 and H2O.The light –independent reactions begin with a
cycle of chemical reactions called the Calvin benson, or C3 cycle. The C3 cycle has three
major parts.

I. Carbon fixation. Carbon dioxide from the air and water combine with
ribulose biphosphate (RuBP) to form phosphoglyceric acid (PGA).

II. Synthesis of Glyceraldehyde 3 phosphate (G3P), using energy from adenine

triphosphate (ATP) and nicotinamide diphosphate (NADPH). G3P may be used
to synthesize organic molecules, such as glucose.

III. Regeneration of RuBP, five molecules of G3P are used to regenerate three
molecules of RuBP again using ATP energy

94
Products of light - independent reaction

To summarize the light reaction, we can write it down as the following reaction:

ATP + NADPH2 + CO2 → C6H12O6 + NADP+ + ADP

PHOTOSYNTHESIS SUMMARY

Figure 5.9 Photosynthesis summary

Source: socratic.org

The light-independent reactions (Calvin cycle) use the energy-carrying molecules (ATP
and NADPH) from the light-dependent reactions along with absorbed carbon dioxide to
form glucose.

95
Guided/Independent Practice

INDEPENDENT PRACTICE: Table Completion

Directions: Complete the table below with the information of light- dependent reactions and
light- independent reactions or Calvin cycle

Light Reactions Dark Reaction

Location

Reactants

Products

96
REFLECTION-ACTION
K-W-L Chart

Directions: Complete the table by filling the 3rd (What I learned about the topic) column
below with the information that was discussed.

What do you know about the What I Wonder/ unsure about What I Learn today about the
topic? the topic topic

Processing Question:
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds,
especially sugars, using the energy from sunlight to maintain normal level of oxygen in the
atmosphere.

As a student, how can you contribute to lessen the carbon dioxide emission in our
environment?

__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________

97
EVALUATION

Performance Task:

Perform an experiment on photosynthesis and submit a Post-

GOAL
Laboratory Report
ROLE You are an Aquaculturist
AUDIENCE Sea Weeds farmer of Zamboanga City
Carbon dioxide emission nowadays getting higher
contribution to global warming and climate change. It was
made known that just like trees, algae and weeds are also
capable of photosynthesis, helping in the absorption of carbon
SITUATION
dioxide in the process.
you are to perform an experiment showing how plants use
carbon dioxide in the process of photosynthesis helping the
weeds to manufacture their food and thrive.
PERFORMANCE/
Laboratory Experiment and Laboratory Report
PRODUCT
Please Refer to the rubric for the grading of the Laboratory
STANDARD
Experiment

98
 Laboratory Experiment: Photosynthesis

Photosynthesis takes place in the chloroplasts within the plant's cells. The chloroplasts
contain special pigments that react to light. Chlorophyll is one of the pigments that can
absorb light in the blue and red spectrum from the visible light spectrum. Chlorophyll does
not absorb light in the green spectrum of light but reflects it instead. This is why leaves with
chlorophyll usually appear green. During the first part of photosynthesis—the light-
dependent reaction—chlorophyll and other pigments harness the light energy to produce
NADPH and ATP, which are two types of energy-carrier molecules. At the same time, water
is split into oxygen (O2) and protons (H+). The next stage is light-independent and is often
referred to as the dark reaction. In this step, the two energy-carrier molecules, NADPH and
ATP, are utilized in a series of chemical reactions called the Calvin cycle. In the Calvin
cycle, the plants take carbon dioxide (CO2) from the air and use it to ultimately make sugars
such as glucose or sucrose. These sugars can be stored for later use by the plant as an energy
source to fuel its metabolism and growth.

Materials:
- 2 Hydrilla plants - 2 test tubes - 2 plastic straws
- Aluminum foil - 2 test tube rubber stopper - Bromothymol blue
- 2 test tube rack

Procedure:

Conducting Hydrilla Plant Setup

1. Label 1 tube with D for dark, and the other test tube with L for light
2. Add half full of bromothymol blue solution on each of the test tubes.
3. Using the plastic straw, place it inside the test tube with bromothymol solution, then
gently exhale/ blow into the straw submerged in the solution. Continue to blow
bubbles into the liquid until it turns yellow- green. This process should take
approximately 15-30 minutes. (Note: never inhale through the straw or allow the
solution to reach towards your mouth).
4. Then carefully place a 4-5 cm sprig of hydrilla plant in each test tube completely
submerging the plant to the solution.
5. Cover the mouth of the test tubes with rubber stoppers, then cover the tube with
aluminum foil.
6. Place the tubes in the sunlight or under a light bank.
7. Remove the foil cover of the test tube labelled as L.
8. Observe both tubes and after 30 mins- 1 hour record what you see.

99
 UNIT III
ENERGY TRANSPORT
Lesson 6: Cellular Respiration

CONTEXT
Learning Competency
At the end of the lesson, the learners can;
a. differentiate the role of oxygen in aerobic respiration from the pathways of electron
flow in anaerobic respiration;
b. distinguish the main features of glycolysis, Krebs cycle, electron transport system,
and chemiosmosis and sequence the chemical events of cellular respiration;
c. compute the number of ATP’s needed or gained in photosynthesis and respiration;
d. explain the advantages and disadvantages of fermentation and aerobic respiration.
Values Integration: Competence

EXPERIENCE
Prelection: Short Response

Short Response

You are an exchange student in Ateneo de Zamboanga University – SHS. One day , you went
to the cafeteria to buy food. When you were to pay for your order you found out that you
only have a US dollar bill inside your wallet instead of a peso bill. You asked the cashier if
you can pay your order in this currency but the cashier refused to accept your money. What
should you do to be able to pay and get the food you ordered?

Share your thoughts to the situation:

___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

100
Concept Notes

Cellular respiration is the set of the

metabolic reactions and processes
that take place in the cells of all
organisms to convert biochemical
energy from nutrients into adenosine
triphosphate (ATP – cell energy),
and then release waste products.

Aerobic Respiration
Producing energy in the form
glucose in the presence of oxygen.

Anaerobic Respiration
Produces a limited amount of ATP in
the absence of oxygen
Figure 6.1 Respiration
Source: veritaspress.com

Respiration Formula
C6H12O6 + 6O2 → 6CO2 + 6H2O + 36 ATP
Glucose + oxygen → carbon dioxide + water + energy

CELLULAR RESPIRATION:
Aerobic Respiration

It is a process of cellular respiration that takes place in

the presence of oxygen gas to produce energy from food
this type of respiration is common in plants and animals
birds, humans, and other mammals. In this process,
water and carbon dioxide as end products.

Aerobic respiration is the process of producing energy in

the form glucose in the presence of oxygen.

The different steps involved in aerobic respiration –

Glycolysis, Krebs cycle, and Electron transport chain

Figure 6.2 Cellular respiration flow

Source: en.wikipedia.org

101
STAGE 1: Glycolysis

Glycolysis is the breakdown of glucose into two molecules of pyruvate. Glycolysis is a

series of catabolic reactions that takes place in the cytosol of the cell.

In glycolysis, there is a distinct enzyme involved in each reaction. The whole process of
glycolysis can be conveniently grouped into the energy- investment phase and the energy
harvesting (or payoff) phase

Figure 6.3 Glycolysis

Source: scienceabc.com

102
§ Energy investment phase – at the onset of glycolysis, two ATP molecules are used to
activate glucose by adding phosphate. eventually, glucose separates into two three-
carbon molecules. Each three- carbon molecule has a phosphate group obtained from
ATP molecules. These three- carbon molecules will go through the same series of
reactions in the energy payoff phase.

§ Energy payoff phase – after the splitting of glucose, another inorganic phosphate is
added into each three- carbon molecule, and thus each of them now has two phosphate
groups these will be used later in synthesizing the two ATP molecules through the
process called substrate- level ATP synthesis or substrate – level phosphorylation,
wherein an enzyme helps attach an inorganic phosphate to ADP to produce ATP. At the
same time, the electrons in each three- carbon molecule are now removed and are
accompanied by hydrogen ions. These hydrogen ions are picked up by NAD+ separately.
Because each NADH molecule carries two high-energy electrons, they can be carried to
the ETC for NAD+ to be recycled and used again, provided that oxygen is available.

PRODUCTS of GLYCOLYSIS
ü 2 pyruvate (final product), 2 ATP net gain, 2 NADH (reaction 6), 2 H2O (reaction 9), 2
H+ (reaction 6)

103
STAGE 2: Kreb’s cycle (Citric Acid Cycle)

Recall that glycolysis produces two pyruvates from each glucose molecule, so each set of
matrix reactions occurs twice during the metabolism of a single glucose molecule.

Pyruvate is split to form CO2 and an acetyl CoA. Simultaneously, NAD+ receives two
electrons and a hydrogen ion to make NADH, the acetyl CoA enters the second stage of the
matrix reactions. Acetyl CoA donates its acetyl group to oxaloacetate to make citrate. CoA is
released. Citrate is rearranged to form Isocitrate. Isocitrate loses a carbon to CO2 forming
alpha ketoglutarate NADH is formed from NAD+. The Alpha – ketoglutarate loses a carbon
to CO2 forming succinate; NADH is forming from NAD+ and additional energy is stored in
ATP. ( at this stage in the mitochondrial matrix reactions, all three carbons of the original
pyruvate have been released as CO2). Succinate is converted to fumarate and the electron
carrier FAD is charged to FADH2.Fumarate is converted to malate. malate is converted to
oxaloacetate, and NADH is formed from NAD.

Figure 6.4 Citric acid cycle

Source: teachmephysiology.com

104
PRODUCTS of KREB’S CYCLE

§ Products of the first turn of the cycle are 1 GTP (or ATP), 3 NADH, 1 FADH2 and 2
CO2.

Because two pyruvate molecules are produced from each glucose molecule, two cycles
are required per glucose molecule.

Citric Acid Cycle PRODUCTS are:

2 GTP
6 NADH
2 FADH2 and
4 CO2

STAGE 3: Electron transport chain

▪ Glycolysis occurs in the cytoplasm of the cell. The reactions of the citric acid cycle
occur in the mitochondria.
▪ A mitochondrion consists of an outer membrane bilayer and an inner membrane
bilayer.
▪ The region between the outer and inner membranes is called the intermembrane space.
▪ The region within the inner membrane is called the matrix.
▪ From one glucose molecule, 10 NADH and 2 FADH2 would be available for oxidative
phosphorylation.
▪ However, the goal of food catabolism is the production of ATP. But only FOUR ATP
have been produced from one glucose so far.

Figure 6.5 Electron transport chain

Source: pin.it/3xEYbxb

105
Chemiosmosis

This pumping process increases the (H+) concentration in the intermembrane compartment
and decrease the (H+) concentration in the matrix; therefore, a H+ gradient is produced
across the inner membrane. Like the thylakoid membrane of the chloroplast, the inner
membrane of a mitochondrion is permeable to H+ only at channels that are coupled with
ATP- synthesizing enzymes. The movement of hydrogen ions down their concentration
gradient through this channels drives ATP synthesis.

Figure 6.6 Chemiosmosis

Source: faculty.ccbcmd.edu

How many ATP can be produced from the overall catabolism of ONE glucose
molecule?

Table 6.1 Overall ATP produced in ONE glucose molecule

Products Conversion to ATP Produced ATP

4 ATP 4 ATP

10 NADH X3 30 ATP

2 FADH2 X2 4 ATP

TOTAL 38 ATP

106
107
Figure 6.7 Summary of electron transport chain and chemiosmosis
Source: qph.fs.quoracdn.net
 CELLULAR RESPIRATION:
Anaerobic Respiration

Cellular respiration that proceeds without oxygen is called anaerobic respiration. Then,
about 2 or 3 billion years ago, oxygen was gradually added to the atmosphere by early
photosynthetic bacteria. Today we are absolutely dependent on oxygen gas, and find it
difficult to imagine that its appearance must have been disastrous for the anaerobic
organisms that evolved in its absence. But oxygen is highly reactive, and at first, its effect on
evolution was so negative that some have named this period the “oxygen catastrophe.”
However, as oxygen gradually formed a protective ozone layer, life rebounded.

Figure 6.8 Anaerobic respiration

Source: elearning-reb.rw

Fermentation
Fermentation is an anaerobic type of cellular respiration produces a limited amount of ATP
in the absence of oxygen. Some plant fungi and bacteria use anaerobic respiration; in fact,
most bacteria may not be able to survive at all when oxygen is present.

You have learned pyruvate is the end product of glycolysis. In the absence of oxygen, this
pyruvate is reduced by the NADH into either lactate or alcohol so that the cells can continue
to work.

The purpose of fermentation is to generate NAD+ which can harvest from glycolysis when
this happens, the NAD+ molecules become available to be reduced in glycolysis once again.
ATP molecules produced by fermentation are lesser compared to ATP produced by the
electron transport chain. However the amount produced is still enough for the cells to
continue working.

108
 Two types of Fermentation

Table 6.2 Alcohol vs lactic acid fermentation

ALCOHOLIC FERMENTATION LACTIC ACID FERMENTATION
▪ The mechanism involves glycolysis. ▪ The mechanism involves hydrolysis
and reduction.
▪ It occurs in bacteria and some fungi ▪ It occurs in lactic acid bacteria and
like yeast. muscle cells of higher organisms.

▪ CO2 and ethyl alcohol are the end ▪ Lactic acid is the end product.
products.
▪ Initial substrate is glucose. ▪ Initial substrate is glucose.
▪ The process is intra-cellar. ▪ The process is extra- cellular or intra-
cellular.

Table 6.3 Fermentation pathways

109
Figure 6.9 Fermentation products
Source: ib.bioninja.com.au

Figure 6.10 Ethanol pathway Figure 6.11 Lactate pathway

Source: 4.bp.blogspot.com Source: 4.bp.blogspot.com

110
SUMMARY

A cellular process that breaks down carbohydrates and

other metabolites with the concomitant buildup of ATP
§ Consumes oxygen and produces carbon dioxide (CO2)
§ Cellular respiration is an aerobic process.
§ Usually involves breakdown of glucose to CO2 and water
§ Energy extracted from glucose molecule:
§ Released step-wise
§ Allows ATP to be produced efficiently
§ Oxidation-reduction enzymes include NAD+ and FAD as coenzymes
§ Electrons are removed from substrates and received by oxygen, which combines
with H+ to become water.
§ Glucose is oxidized and O2 is reduced

Phases of Cellular Respiration

Cellular respiration includes four phases:

Glycolysis is the breakdown of glucose into two molecules of pyruvate
ü Occurs in cytoplasm
ü ATP is formed
ü Does not utilize oxygen

Citric acid cycle

ü Occurs in the matrix of the mitochondrion and produces NADH and FADH2
ü In series of reaction releases 4 carbons as CO2
ü Turns twice (once for each pyruvate)
ü Produces two immediate ATP molecules per glucose molecule

Electron transport chain

ü Extracts energy from NADH & FADH2
ü Passes electrons from higher to lower energy states
ü Produces 32 or 34 molecules of ATP

111
Guided/Independent Practice

INDEPENDENT PRACTICE: Table Completion

Directions: Complete the table below showing the major events and features of cellular
respiration you can use the word/ phrase more than once.

STAGE REACTANTS END PRODUCTS

Glycolysis

Citric Acid Cycle

Electron Transport and

Chemiosmosis

112
REFLECTION-ACTION
Modified SQ2R

Topic: _________________________________
Reference: ____________________________

Summary:
Why do you think Cellular Respiration is essential to humans? Briefly discuss the process
of cellular respiration.
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Questions:
Write one question you still have in mind about cellular respiration.
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Reflection:
Human body requires energy to perform daily tasks. In order to do so, you need to consume
foods rich in energy sources such as carbohydrates which is a good source of glucose to
initiate cellular respiration producing energy in the form of ATP. During starvation, what
do you think will happen to you if you were not able to consume enough food? What might
happen if you eat too much food?
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Real-life Application:
How would you plan to improve/lessen your daily consumption of food?
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Writing to Learn Worksheet: Modified SQ3R

DEVELOPED BY ANITA R. TAGADIAD
2000

113
EVALUATION
A. Summative Exam: Photosynthesis and Cellular Respiration can be access in your Eclass

B. Grand Performance Task: A Collaborative Task of STM 123 and STM 124

“The ART of FERMENTATION”

Produce a fermented product out of common materials found
in your respective households or in the community: (Choose
one)
Wine
GOAL Vinegar
Kimchi
Bread
Pickled fruits or vegetables (e.g. ‘atchara’)
Others (you may suggest to your instructor for approval)

ROLE Venturing entrepreneur with knowledge on food technology

AUDIENCE Community, Small business owners
Due to the pandemic, a lot of people were affected especially
those who lost their jobs and those who are owners of small
businesses. The government encourages everyone to venture
on other opportunities using materials that can be found in
SITUATION their respective communities. As a starting entrepreneur with
knowledge on food technology, you would like to help those
who are jobless and those who are interested in producing
food products using materials found in the community that
they can sell and profit on.

114
 VLOG (FPBA)
You are to create a video documentation of yourself working on
your chosen fermented product. The vlog will not be focusing on
the editing of the video or anything alike, instead it will focus on
the step-by-step process in making your product. This can be done
through a time-lapse video.
The group is given a maximum of 20 minutes and each member
must document the step-by-step process of doing the fermentation
product from start until the end. Each member is given 3 minutes of
the time-lapse video in the making of their product and the
remaining times will be used for the discussion of the concept
based on the guide questions given.
PERFORMANCE/
INFOGRAPHIC (Performance Task)
PRODUCT
Since there will be no procedure to be provided, each group must
come up with their own procedure in the making of their selected
product.
The group must create an infographic about the chosen product
which can be shared, used, and followed by other people, especially
those who are managing their small businesses that would want to
replicate your procedure. Include the chemical reactions that occur
in the fermented product in your infographic. The infographic
should contain the ingredients or materials used and step-by-step
procedure in creating the product.
The infographic should also be a way for you to be able to advertise
your product and to be easily understood by the public.

You will be graded based on the following standards:

Vlog: Content, Organization of Information, Visual Elements and
STANDARD Audio, Length of Time and Timeliness
Infographic: Content, Organization of Information, Layout and
Design, and Timeliness.

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GUIDE QUESTIONS:

Instruction: In the given 20 minutes maximum time of your vlog, make sure to answer the
following question in the last 3-5 minutes of your vlog.

BIOLOGY RELATED QUESTIONS:

1. Discuss thoroughly the process of cellular respiration that occur in your product.
Make sure to highlight important events and processes.
2. How long does it take for you to have your finish product? Why do you think it took
you that length of time?
3. What is/are the most important ingredient/s used to in the fermentation process of
your product? Discuss thoroughly.

CHEMISTRY RELATED QUESTIONS:

1. How is fermentation related to chemistry? What chemistry principles are involved in

the production of your chosen product?
2. What type of chemical reaction did your product undergo? Explain why and present
the complete and balanced equation.
3. What chemistry-related practice can you suggest to improve the quality (appearance,
shelf-life, taste, and etc.) of your chosen product? Explain how you would do it and
the concept behind it.

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 VLOG RUBRIC
CRITERIA EXCELLENT GOOD FAIR DEVELOPING
(5) (4) (3) (2)
The vlog clearly The vlog clearly The vlog did not The vlog did not
showed the process showed the process clearly show the show the process
of making the of making the process of of making the
product. Answers product. There making the product. The
Content were answered were several errors product. There answers were
(x3) accurately based on on the answers were several factually
the guide questions based on the guide errors on the incorrect based
questions answers based on on the guide
the guide questions
questions
Output presents the Output shows the Output is poorly Output has poor
content in an information in organized and/or organization
Organization
interesting way that which an audience difficult for a which makes it
of Information
can be watched over or viewer can viewer or impossible to
(x2)
and over to see more follow to learn and audience to learn from.
each time. understand. follow.
Visual elements and Some of the visual Some of the Visual elements
audio are clear and elements and audio visual elements and audio were
Visual accurately were not clear but and audio were not clear that did
elements and communicates the still was able to not clear that did not help to
audio goal communicate the not help to communicate the
(x2) goal communicate the goal
goal
The vlog did not The vlog exceeded The vlog The vlog
exceed the time 1-2 minutes to the exceeded 3-4 exceeded more
requirement. time requirement minutes to the than 5 minutes to
Length of Time
Maximized the time and was able to use time requirement the time
(x1)
very well. the time well. and was able to requirement and
use the time just was not able to
fine. use the time just
well.
Output was Output was Output was Output was
submitted before/on submitted hours or submitted 2 days submitted 3 days
Timeliness the due date.
(x1) a day after the due after the due after the due date
date. date.

117
 INFOGRAPHIC RUBRIC

CRITERIA EXCELLENT GOOD FAIR DEVELOPING

(5) (4) (3) (2)
Content The infographic The infographic The The infographic
(x2) clearly shows all clearly shows all infographic did not show all
of the of the vaguely shows of the
ingredients/mate ingredients/mater all of the ingredients/mater
rials and ials but there are ingredients/mat ials and there is
conveys the lapses in the step- erials and there no step-by-step
step-by-step by-step are lapses in procedure of
procedure of procedure of the step-by-step making the
making the making the procedure of product
product product making the
product
Organization Output presents Output shows the Output is Output has poor
of Information the content in an information in poorly organization
(x2) interesting way which an organized which makes it
that can be audience or and/or difficult impossible to
viewed over and viewer can for a viewer or learn from.
over to see more follow to learn audience to
each time. and understand. follow
Layout and The infographic The infographic The The infographic
Design is exceptionally is attractive in infographic is is poorly
(x2) attractive in terms of design, somewhat designed and
terms of design, layout and pleasing to the
distractingly
layout and neatness. Some eyes though it
neatness. Visual of the visual may be a bit messy as a result
elements and elements and messy with the of rushed
graphics used graphics used are design and preparation.
are clear and clear and layout. Most of Visual elements
appropriate in appropriate in the visual and graphics
communicating communicating elements and used were
the goal of the the goal of the graphics used
project project were clear and unclear and
inappropriate in inappropriate in
communicating communicating
the goal of the the goal of the
project project
Timeliness Output was Output was Output was Output was
(x1) submitted submitted hours or submitted 2 days submitted 3 days
before/on the due a day after the due after the due after the due date
date.
date. date.

118
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