STEM 11 : GENBIO 1 NOTES

GENERAL BIOLOGY 1
FOR SHS STEM 11: 1ST SEM (FIRST QUARTER) @rivermemories on twt

# LESSON !
➥ CELL THEORY
What are Cells? They are considered the basic building blocks of
all living things. They provide a structure for the body to take in
nutrients from food, convert nutrients to energy, and carry out
specialized functions. They also contain the body’s hereditary
material.

THE CELL THEORY

Description: This is a scientific theory stating the following
principles:
a) All living organisms are made up of cells.
b) The cell is the basic unit of structure and organization
of organisms.
c) All cells come from pre-existing cells.

THE CELL HISTORY

➔ Zacharias and Hans Janssen - came up with the
microscope using two lenses in a tube.
➔ Anton van Leeuwenhoek - the first person to observe
living cells that he called animalcules.
➔ Robert Hooke - discovered the cell through a thin
slice of cork with a honeycomb structure. He thought of
the word “cells” and compared it to little rooms.
➔ Theodore Schwann - proposed that all animals are
made up of cells.
➔ Matthias Schleiden - proposed that all plants are
made up of cells.
➔ Robert Brown - first discovered the nucleus of cells.
➔ Felix Dujardin - discovered the fluid content of cells.
➔ J.E. Purkinje - named the fluid content of the cell
protoplasm
➔ Carl Heinrich Braun - proposed that the cell is the
basic unit of life.
➔ Rudolf Virchow - proposed that cells arise from pre-
existing cells.
➔ Aristotle - “Father of Biology”

# LESSON !
➥ CELL STRUCTURE
What are Cell Organelles? They are referred to as little organs. All
cells have the main three: Cell Membrane, Cytoplasm, and DNA.

They are complex and their components perform various

functions which can be similar to factories.

The 2 main types of cells are

● Eukaryotic Cells (Eukaryotes)
● Prokaryotic Cells (Prokaryotes)

STRUCTURE OF EUKARYOTIC CELLS

ANIMAL CELLS:
Nucleus - the "Control System" which contains the genetic
material DNA (chromosomes).
Nucleolus - the site for ribosome synthesis.
Cell Membrane - outer covering that supports and
protects the cells as a guard. It helps in monitoring the
movement in and out.
Cytoskeleton - gives structural strength and is
responsible for cellular movement.
Centrosome - for reproduction; aids in cell division.
Cytoplasm - jelly-like material where all organelles are
embedded. This contains the Cytosol which is its liquid part.

Golgi Apparatus - modifies, concentrates, and packs

directing the substances to the required destinations.
Endoplasmic Reticulum - a channel for transport and
provides mechanical support. The Rough ER is the part where
there are ribosomes attached to them whilst also helping in
facilitating protein synthesis and conversion of amino acids.
While, the Smooth ER lacks ribosomes and facilitates lipid
synthesis, steroid synthesis, and other biochemical reactions.
Mitochondria - produces and provides energy for cellular
metabolism. The powerhouse of the cell. It also produces ATP.
Lysosome - protects the cell by destroying foreign
invaders like bacteria and viruses.
Vesicles - help transport materials that organisms need
to survive.

PLANT CELLS:

Cell Wall - the most prominent part of a plant cell.

Chloroplasts- converts light energy into chemical energy
as food for plants.
Leucoplast - colorless plastids found in storage cells of
roots and underground stems.
Chromoplasts - noticeably in warm colors: yellow, red,
and orange. Xanthophyll (yellow) Carotene (orange-red)
Vacuole - a sack-like structure that stores various
substances mostly water in plant cells.

● Prokaryotic Cells (Prokaryotes)

Bacterium Cells

Capsule - the slime, outermost layer.

Cell Wall - external plasma membrane.
Flagellum - responsible for the movement of the cell.
Pili- these are hairlike projections that play a role in the
movement and are involved in facilitating infections.

THEIR SIMILARITIES & DIFFERENCE:

SIMILARITIES:
➢ They both have an outer cell membrane.
➢ They both have ribosomes and DNA.
➢ They both have cytoplasm and cell walls.
PROKARYOTES:
➢ They have no nucleus.
➢ They don't have membrane-bound organelles.
➢ They are connected to: Archaea and Bacteria.
➢ They have existed since 4 billion years ago.
➢ They are smaller in size with the simplest composition.
➢ They are the largest group.
EUKARYOTES:
➢ They can be unicellular or multicellular.
➢ They have a nucleus
➢ They have membrane-bound organelles.
➢ They are connected to: Protists, Fungi, Plant, and
Animals
➢ They are larger in size with a more complex
composition.
➢ They are the advanced group.

# LESSON !
➥ TISSUES
What is a Tissue? It is a group of specialized cells of the same
type that perform a common function. There following are the
four types of tissues:
a) Epithelial (body cavities and glands)
b) Connective (binds different organs together)
c) Muscle (movement)
d) Nervous (senses and transmits impulses)

+ WHAT ARE EPITHELIAL TISSUES?

Definition: This covers or lines the body cavity and forms glands.
This includes the following:
Squamous- can be found in the lining of lungs and
blood vessels, as well as in the mouth and esophagus. It
supplies a friction-free surface for blood flow.
Cuboidal- can be found in the lining of kidney
tubules. It absorbs molecules.
Columnar- can be found in the small intestine,
stomach, and oviducts. It protects, supports, and
absorbs nutrients.
Ciliated Columnar- can be found in the trachea and
nostrils. It sweeps impurities toward the throat.
Glandular Columnar- can be found in the small
intestine, respiratory passage, and different glands. It
produces mucus and keeps the respiratory passage
moist.

+ WHAT ARE CONNECTIVE TISSUES?

Definition: This binds different organs together and supports the
body. This is developed from mesoderm, also known as
mesenchyme.

There are 3 types of connective tissue based on the matrix:

1. Proper- matrix soft and fibrous.
2. Skeleton- dense and mineralized matrix.
3. Vascular- liquid and fibers-free matrix
It composes 30% of the body weight. Here are the following
examples:
Adipose Tissue - facilitates energy storage and
insulation.
Fibrous Connective Tissue - it occurs in tendons
(muscle to bone) and ligaments (bone to bone)
Cartilage - rigid connective tissue that is composed
of collagenous fibers and chondroitin sulfate.
Bone - made up of osteocytes. It had 2 types: dense
and spongy.
Blood - contains water, salt, and proteins separated
by plasma.
● Red - erythrocytes, hemoglobin, and carries
oxygen.
● White - leukocytes, the immune system.
● Platelets - are thrombocytes, function in
blood clotting

+ WHAT ARE NERVOUS TISSUES?

Definition: This is involved in the integration of stimulus and
control response of the body. There are 2 main cell types:
neurons (transmit nerve message) and glial cells (surround
neuron)
Dendrites - receive information
Cell Body- contains all the cell organelles.
Axon - conducts the message away
from the cell body.

+ WHAT ARE MUSCLE TISSUES?

Definition: this facilitates movement by contraction of muscle
fibers. Here are the following examples:

Skeletal - muscles attached to the bones, voluntary

Smooth - muscle is found mostly in digestive,
reproductive, and blood vessels, involuntary
Cardiac - found in the heart, involuntary

+ GENERAL PLANT ORGANIZATION

What? Plants cells are formed at meristems that develop into
cell types which are grouped into categories.
Dermal (Skin)
- Epidermis
- Guard Cells
Ground
- Cortex
- Parenchyma
- Sclerenchyma
- Collenchyma
- Pith
Vascular (Root)
- Xylem
- Phloem
- Cambium Cells

#LESSON !
➥ CELL MODIFICATION
What are Specialized Cells? They perform special functions in
multicellular organisms. Plants and animal cells are specialized
to carry out jobs efficiently.

ANIMAL SPECIALIZED CELLS:

1. Red Blood Cell - carries oxygen from the lungs to the
body and carbon dioxide from the body back to the
lungs.
2. White Blood Cell - kills bacteria to protect our lives.
3. Ciliated Epithelial Cell - moves mucus out of the
body and helps the ovum to move.
4. Nerve Cell - carry nerve impulses.
5. Muscle Cell - allows the body to move.
6. Gametes / Sex Cell - Sperm Cell (Male Parent) and
Ovum Cell (Female Parent).

PLANT SPECIALIZED CELLS:

1. Root Hair Cell - large surface area for water
absorption. Thin wall with no chloroplasts. Minerals and
water from the soil.
2. Palisade Cell / Leaf Cell - carry out photosynthesis to
help make food.
3. Xylem Cell - found in a stem that helps in the
transport of water and provides support.

# LESSON !
➥ CELL CYCLE
What is Cell Division? When the “parent cell” divides into
“daughter cells”, then the process repeats. In the cell cycle,
● Interphase- cells are growing, replicating DNA, and
doing cell functions.
● M Phase- the splitting of cytoplasm and the formation
of new cells.

Remember the following terms!

● Chromosomes- In the nucleus of each cell, the DNA
molecule is packaged into thread-like structures called
chromosomes.
● Chromatin - a substance within a chromosome consisting
of DNA and protein.
● Chromatids- A sister chromatid refers to the identical
copies (chromatids) formed by the DNA replication of a
chromosome, with both copies joined together by a common
centromere.
● Centromere- structure in a chromosome that holds
together the two chromatids (the daughter strands of a
replicated chromosome). The centromere is the point of
attachment of the kinetochore.
● Centrioles- they produce spindle fibers that attach to the
chromosomes.
● Mitotic spindle- During mitosis, the spindle fibers are called
the mitotic spindle. Long protein fibers called microtubules
extend from the centrioles in all possible directions, forming a
spindle.

+ MITOIC PHASE
What? This occurs in body/somatic cells. It produces 2 identical
diploid daughter cells

➔ Prophase- the nucleus is still present. Chromatin is

condensing (thickening and visible) Centrioles migrate to
opposite poles
➔ Prometaphase- there is nuclear envelope breakdown.
Chromosomes are more condensed
➔ Metaphase- the chromosomes line up in the middle of the
cell. Spindle fibers are fully developed. Chromosomes are
attached to the spindle fiber
➔ Anaphase- the sister chromatids are separated, and they
move to the opposite sides of the cell. This is the shortest
stage of mitosis.
➔ Telophase- the organelles are well-arranged on each
side. Chromosomes are at complete opposite ends. Two new
daughter nuclei are forming on these two sides. Nucleolus
starts to appear. Chromosomes are less condensed.
➔ Cytokinesis- this occurs when cytoplasm from the original
cell divides and forms 2 new cells. The cell membrane forms
a cleavage furrow in animal cells pulled inward by a tiny
filament. In plant cells, cell plate form between two nuclei. This
is produced by the Golgi body which supplies the new plasma
membrane.

+ MEIOSIS PHASE
What? This occurs in sex/gamete cells. It produces 4 haploid
daughter cells. In humans, the haploid cells made in meiosis are
sperm and eggs.

MEIOSIS I
● Prophase I - identical to Prophase in mitosis.
● Metaphase I - instead of all chromosomes pairing up along the midline
of the cell as in mitosis, homologous chromosome pairs line up next to each
other. This is called synapsis. Homologous chromosomes contain the
matching alleles donated by the mother and father. This is also when
meiotic recombination, also known as "crossing over" (see below) occurs.
This process allows for a genetic shuffling of the characteristics of the two
parents, creating an almost infinite variety of possible combinations. See
the close-up diagram below.
● Anaphase I - instead of chromatids splitting at the centromere,
homologous chromosome pairs (now shuffled by crossing over) move
along the spindle fibers to opposite poles.
● Telophase I - the cell pinches and divides.

MEIOSIS II
● Prophase II - it is visibly obvious that replication has not occurred.
● Metaphase II- the paired chromosomes line up.
● Anaphase II: - the chromatids split at the centromere and migrate along
the spindle fibers to opposite poles.
● Telophase II- the cells pinch in the center and divide again. The final
outcome is four cells, each with half of the genetic material found in the
original. In the case of males, each cell becomes a sperm. In the case of
females, one cell becomes an egg and the other three become polar
bodies which are not used.

Why do cells divide? They divide for the growth of living things.
Organisms grow because cells are dividing to produce more
and more cells.

SIGNIFICANCE OF MITOSIS:
● Development and Growth
● Cell Replacement
● Regeneration
● Asexual Reproduction
SIGNIFICANCE OF MEIOSIS:
● Formation of Gametes
● Genetic Information
● Maintain Chromosome Number
● Assortment of Chromosomes
● Mutation

#: LESSON !
➥ GENETIC DISORDERS
Definition: These are diseases, syndromes, or other abnormal
conditions that are caused by chromosomal alterations. They
are typically present at birth.

CANCER CELLS - A group of diseases that involve irregular

growth and reproduction of cells Cancer occurs when genes
involved in the cycle, specifically with checkpoints are altered
(growth factors).

Remember! Cancer is basically a disease of uncontrolled cell

division. Its development and progression are usually linked to a
series of changes. This shows how being too active can also be a
disadvantage.

The improper copying of DNA produces two types of errors or

mutations.
● Silent Mutations have no impact on the DNA
sequence.
● Missense Mutations often impact associated
functions.

OTHER EXAMPLES OF GENETIC DISORDERS:

1. Klinefelter Syndrome (Klinefelter's, KS, or XXY)
2. Patau’s Syndrome (Trisomy 13)
3. Turner Syndrome
4. Down Syndrome (Trisomy 21)
5. Cri-du-chat Syndrome (cat's cry)

# LESSON !
➥ CELL MEMBRANE STRUCTURE AND
FUNCTION
THE FLUID MOSAIC MODEL
-> This was proposed by Seymour Jonathan Singer and Garth L.
Nicolson in the early 1970s. He proposes that the cell membrane
is made up of 2 main layers – lipids and Proteins.

What is the Cell Membrane? Every cell is encircled by a

membrane that fences its interior from the surrounding. Without
it, the cells will diffuse out.

This is also semi-permeable. The membrane is a mosaic

(mixture) of different protein molecules floating in a bilayer
(double layer) of phospholipids.

● Each phospholipid has a hydrophilic (water-loving)

head and hydrophobic (water-hating) tails.
● It is made from a phospholipid bilayer: a hydrophilic
(water-loving) head and a hydrophobic tail (water-
fearing).
● It also has cholesterol and different proteins that aid in
substance transport.

As mentioned earlier, this is primarily composed of a mix of

proteins and lipids.

+ CELL MEMBRANE LIPIDS

● Phospholipids- Major component of the cell
membrane. They make up 75% of the cell’s surface
membrane. This is selectively permeable– small
molecules and lipid soluble molecules pass through
easily.
● Cholesterol- selectively dispersed between
membrane phospholipids. It makes the cell membrane
more rigid and prevents the membrane from being too
fluid and breaking up.
● Glycolipid- occurs on the external surface of the
membrane. Maintains the stability of the membrane and
facilitates cell-to-cell interactions.

+ CELL MEMBRANE PROTEINS

● Glycoprotein- is a transmembrane protein that spans
the entire membrane. It acts as a channel, transporter,
and receptor that binds to target molecules like
hormones.
● Receptor protein- It helps cells communicate with
their external environment through the use of hormones,
neurotransmitters, and other signaling molecules.
● Globular Protein- transports molecules across cell
membranes through facilitated diffusion.

+ KEY CONCEPTS & IMPORTANCE:

● Cell Membrane is a multifaceted membrane that
envelopes the cytoplasm.
● Protection and support.
● Proteins and lipids are the major components.
● The most complex component is protein.
● Cholesterol helps in stability and flexibility.
● Phospholipids arrange in a bi-layer way with a semi-
permeable mechanism.

# LESSON !
➥ CELL TRANSPORT
Definition: This refers to the movement of substances across the
cell membrane. A lot of things move through the lipid layer easily
but other substances need the assistance of protein.

Remember! Being selectively permeable is the most important

feature of a phospholipid layer.

What is Membrane Permeability? Biological membranes are

physical barriers that allow small uncharged particles to pass.
They are described as semi-permeable because soluble
molecules and small molecules pass through but big molecules
cannot. This is where they will shift to channels or pores through
the help of proteins for entry.

What is TONICITY? The ability of an extracellular solution to

make water move into or out of a cell by osmosis.
● Hypertonic- higher concentration of solute. Resulting
in cell shrinking and becoming plasmolyzed.
● Hypotonic- low concentration of solute. Resulting in
cell expansion and turgidity.
● Isotonic- equal concentration of solute and solvent.
There is no movement in solvents.

What is PASSIVE TRANSPORT? The movement of substances

across the membrane without energy expenditures.

1. Simple Diffusion- the movement of molecules from

high concentration to low concentration (small and
nonpolar molecules)

2. Facilitated Diffusion- it uses channel proteins to

allow large and polar molecules to pass through.
a. Channel Mediated- open close
b. Carrier Mediated- changes shape

3.Osmosis- diffusion of water/ liquid molecules. They

pass through a channel protein called aquaporin. Water
moves to areas with higher solute content.

What is ACTIVE TRANSPORT? The movement of substances

that use energy in the form of ATP.
1. Endocytosis- movement from outside to the inside of
the cell by the plasma membrane folding inwards
trapping the substance to form a vesicle.
a. Phagocytosis- cellular eating (white blood cells)
b. Pinocytosis- cellular drinking (egg cells)
2. Exocytosis- movement from the inside of the cell
towards the outside of the cell and the usage of vesicles.
It can be used to dispose of waste or distribute nutrients
throughout the body.

# LESSON !
➥ ENZYMES
Remember! Anselme Payne was a French chemist known for
discovering the enzyme diastase and carbohydrate cellulose.

What are ENZYMES? All living things have enzymes.

● They are proteins that help speed up metabolism, or
the chemical reactions in our bodies.
● They build up some substances and break others
down.
● "Catalysts" are compounds that accelerate a reaction
without being changed. These proteins that act as
biological catalysts speed up chemical reactions.
● They are compounds that facilitate chemical
reactions.

+ What is an ACTIVE SITE?

● Acting as a template for substrate orientation
● Stressing the substrates
● Stabilizing the transition state
● Providing a favorable microenvironment
● Participating directly in the catalytic reaction.
+ What is a Substrate?
● This is any substance that reacts to the active site of
an enzyme.

-> What are COFACTORS?

- a non-protein chemical compound that tightly and
loosely binds with an enzyme or other protein molecules.

-> What are COENZYMES?

- small, organic protein molecule that carries chemical
groups between enzymes.

LEARN MORE W/ THESE OTHER SOURCES:

● https://www.sciencefacts.net/cell-cycle.html
● https://www.khanacademy.org/science/ap-biology/heredity/meiosis-and-genetic-
diversity/a/phases-of-meiosis
● https://www2.nau.edu/lrm22/lessons/mitosis_notes/meiosis.html
● https://www.nagwa.com/en/explainers/726129032520/

ᓚᘏᗢ ≽ ^•⩊⩊•^≼
≼
Thank you!
Disclaimer: This may not completely cover all of the sub-topics under the subject: General Biology 1. Do keep in
mind that this is just a compilation of my notes under this sub that I've also used as reviewers hence the
indication of key terms and such. That’s all! Stay safe and study well :))