General Biology

Traditional Branches of Biological Science

 Taxonomy – study of naming and classifying organisms

 Cytology – study of structures and functions of cells
 Embryology – study of formation and development of organisms
 Anatomy – study of structures and parts of organisms
 Physiology – study of functions of living organisms and their parts
 Biochemistry – study of biochemical compositions and processes of living things
 Genetics – study of heredity and variation
 Evolution – study of origin and differentiation of various organisms
 Ecology – study of relationships of organisms with each other and their environment

Modern Branches of Biological Science

 Bioinformatics – study of biological data using computer programs

 Genomics – study of the entire genetic material of an organism
 Molecular biology – study of molecules that make up the cells of living organisms
 Pharmacogenomics – study of how genes affect a person’s response to drugs
 Proteomics – study of the different proteins in an organism
 Synthetic biology – study of artificial biological systems
 Systems biology – study of computational and mathematical modeling of biological systems

Life and its Beginnings

 Redi’s Experiment – he concluded that life arose from living matter, not from spontaneous generation
in the meat
 Needham’s Experiment – he concluded that life in the broth was caused by spontaneous generation
 Spallanzani’s Experiment – life occurred from something that entered the unsealed flask and that it
was the one responsible for life to grow
 Pasteur’s Experiment – this experiment supported the theory of biogenesis and rejected
spontaneous generation

Current beliefs about the origin of life

 Divine creation – it is believed that life forms and everything in the universe were created through a
supernatural power rather than naturalistic means
 Spontaneous origin – life evolved from inanimate matter
 Panspermia – a meteor or cosmic dust may have carried to earth which started the evolution of life
Cellular Respiration – the process by which energy is release by the breakdown of food substances

Metabolism – the sum of all chemical processes and energy changes

happening inside the body of an organism

Nutrition – the process by which organisms acquire food

Excretion – the process of removing waste

Homeostasis – the maintenance of the body’s internal environment

Humans and animals derive Green plants obtain energy Fungi obtain energy by
energy indirectly from the sun directly from sunlight via absorbing nutrients from dead
by ingesting food photosynthesis or living things

Locomotion/motility – most animals can move from one place to another by walking, flying, swimming, gliding
or jumping.

Tropism/response – the reaction of an organism to stimuli

Sensitivity/irritability – the ability of an organism to respond appropriately to a stimulus

Development - the progressive changes in size, shape, and function during the life of an organism

Intussusception – process in which living things exhibit growth from within the cells

Accretion – growth by external addition of substances

Growth – is an increase in size and volume

Reproduction – process by which genetic information is passed on from one generation to another as
organisms produce offspring

Population – a group of the same kind of organisms living in an area

Community – different populations sharing the same habitat

 Life in a Cell
Cell theory:

 All organisms are composed of one or more cells

 Cells are the smallest and basic units of structure and function in organisms
 Cells arise only from previously existing cells

Basic Cell types

 Cell membrane/plasma membrane – an outer boundary. Regulates the passage of materials into and
out of the call. It separates the cytoplasm from the external environment
 Cytoplasm – a gel-like substance making up the cell’s internal environment
 Nucleus – central genetic region where inherited information in the form of DNA is stored

Prokaryotic cells (Bacteria and Archaea) – cells that do not have a nucleus

Eukaryotic cells - cells that contain a nucleus and organelles, and are enclosed by a plasma membrane.

Pilus - a pilus is a hair-like appendage found on the surface of many bacteria and archaea.

Capsule - is a large structure of many bacteria.

Cell wall - is a structural layer surrounding some types of cells, just outside the cell membrane

Membrane Structures

 Cholesterol molecules - help strengthen the cell membrane, making it more flexible but less fluid
 Carbohydrates – attached to membrane proteins serve as identification tags, enabling cells to
distinguish one type of cell from another

Membrane proteins

 Transport proteins – extend from phospholipid layer to help materials cross the membrane
 Channel proteins – form tunnels that helps cells to import or export needed materials and expel
wastes
 Cell recognition proteins – enable cells to distinguish own cells
 Enzymatic proteins – participate in metabolic reactions such as degradative and synthetic reactions
 Cytoskeleton protein – act as muscle and skeleton to maintain cell shape and motility
 Junction proteins – assist cell-to-cell adhesion and communication between cells
 Receptor proteins – facilitate exchange of signals with other cells by changing shape
Nuclear envelope - is a double membrane layer that separates the contents of the nucleus from the rest of
the cell. It is found in both animal and plant cells.

Nuclear pores – allow large molecules to pass between the nucleus and cytoplasm

Nucleolus – dense region where small organelles essential for making proteins are assembled

Ribosomes - particle consisting of RNA and associated proteins found in large numbers in the cytoplasm of
living cells.

Nucleus - is a membrane-bound structure that contains a cell's hereditary information and controls its
growth and reproduction

Vacuoles – is a fluid-like sac for the storage of materials needed by the cell that includes water, food
molecules, inorganic ions, and enzymes

PARTS AND FUNCTIONS

1. Nucleolus - produce and assemble subunits which form the ribosome.

2. Nucleus - Control gene expression and mediate the replication of DNA during the cell cycle
3. Rough endoplasmic reticulum - Produce proteins for the rest of the cell
4. Peroxisome - breakdown of very long-chain fatty acids by beta-oxidation.
5. Ribosome - Decoding the message and the formation of peptide bonds
6. Golgi apparatus - responsible for transporting, modifying, and packaging proteins and lipids into
vesicles for delivery to targeted destinations.
7. Cell membrane - Barrier keeping the constituents of the cell in and unwanted substances out and
second, to be a gate allowing transport into the cell of essential nutrients and movements from the
cell of waste products.
8. Smooth endoplasmic reticulum - Helps in the manufacture of fat molecules or lipids, important for
cell function
9. Mitochondrion - Generate large quantities of energy in the form of adenosine triphosphate (ATP)
10. Lysosome - They break down excess or worn-out cell parts. They may be used to destroy invading
viruses and bacteria
11. Cytoplasm - Buffer and protects the genetic material of the cell
12. Vesicles - store and transport materials with the cell
13. Centrosome - the microtubules, so it's called the microtubules organizing center
14. Cell membrane - Barrier keeping the constituents of the cell in and unwanted substances out
Mitochondria (powerhouse of cell) – supply energy to the cell. They are round to oval-shaped organelles
and have to membranes
Plastids – are double membrane-bound organelles found inside plants and algae. They are responsible for
activities related to making and storing food

Thylakoids – are in the chloroplast membrane. Contains chlorophyll, a light-absorbing pigment that gives
plant their green color and plays a role in photosynthesis
Stroma – is the liquid portion of the chloroplast
 Lipids (including fats and oils) store
energy for cells, and they provide the
-Nucleotides are complex molecules made core of cell membranes and other
of a five-carbon sugar (ribose or structures.
deoxyribose), one or more phosphate  Many hormones are also lipids.
groups, and an organic nitrogen-containing  Lipids do not readily dissolve in
base.
water, and their structure is a chain
-Nucleotides are extremely important as of carbon atoms with attached
signaling molecules (they carry information hydrogen atoms. This structure
between cells, tissues, and organs) and as makes them part of the family of
sources of energy within cells. hydrocarbons

-They also form long chains called

ribonucleic acid (RNA) or deoxyribonucleic
Centrosome – is a small dense region of cytoplasm that serves as the main microtubule organizing center
(MTOC) where microtubules are organized and assembled
Centriole - cylindrical organelle near the nucleus in animal cells, occurring in pairs and involved in the
development of spindle fibers in cell division.
Cilia - hair-like structures that extend outward from the surface of many animal cells. These structures are
important in the cell cycle and replication
Flagella – looks like a whip or a tail. It is used by cells and microorganisms for movement
Cytoskeletons - organizes other constituents of the cell, maintains the cell’s shape, and is responsible for the
locomotion of the cell itself and the movement of the various organelles within it.
Microtubules – are filaments characterized to be lengthy and the thickest among the filaments
Intermediate filaments – smaller than microtubules and rope-like in appearance
Microfilaments – are the thinnest among the cytoskeletons and also known as actin filaments
Extracellular matrix – which act as a glue to bind the cells together in tissues and provide mechanical strength

Types of microscope
 Compound microscope – used to examine cells and section of tissues with the use of sunlight or
artificial light to illuminate the object being examined
 Stereo microscope used to examine the external structures of specimen such as insects
 Phase-contrast microscope – used to examine highly transparent objects such as unstained cells
 Electron microscope – used streams of electrons to enlarge objects
 Transmission electron microscope (TEM) – used to study internal structures of cells through sectioned
Specimens
 Scanning electron microscope (SEM) – used to examine the three-dimensional surface structures or
Shapes of objects such as viruses.
 Fluorescent microscope – illuminates objects stained with fluorescent dyes that glow in the dark. It is
used in studying the location of certain organelles or substances inside the cell.
 Confocal scanning microscope – used to examine the three-dimensional structure of a cell or
organelle without cutting the specimen into sections. It uses laser beams to scan across the specimen.

Parts of Nucleus
 Nuclear envelope – surrounds the nucleus,
Separating it from the cell’s cytoplasm. It is double
Membrane
 Nuclear pores – the holes of the nuclear envelope
 Nucleolus – region where small organelles are essential
For making proteins are assembled. It is the control
Center of the cell