TAXONOMY

Taxonomy
         - science of naming, classifying, and identifying organisms
         - systematics

Levels of Classification (taxa)

     1. Kingdom          4. Order      7. Species
     2. Phylum             5. Family
     3. Class                 6. Genus

Phylogeny
          - natural system of classification that is based on the evolutionary history or genealogy shared by a group of organisms.

Phylogenetic Trees
         - show how related organisms evolved from common ancestors
Method:
     Cladistics
           - involves identifying shared derived traits

Carolus Linnaeus
     - binomial nomenclature
genus

• tells more about the organism
• always capitalized

species

• lower case

Genus and species form the scientific name.  It is either italicized or underlined.

Aristotle
          - father of animal classification
          - land, air, water
          - "species", belonging to the same kind

Artificial Systems
         - took into account only a few characteristics
         - Aristotle and Carolus Linnaeus

EVOLUTION

Early Concepts of Evolution

Aristotle: nature evolved gradually from the simple to the more complex and from imperfect to perfect

Lucretius: wrote an evolutionary explanation of the origin of plants and animals

Leonardo da Vinci: put forward the theory of catastrophism
                              explains that fossil found in rocks resulted from a succession of fires and flood
                              that destroyed all things some time in the prehistoric past

Theory of Uniformatarianism

James Hutton: concluded that the formation of sedimentary deposits was due to geological forces
                       of erosion, sedimentation, uplift, and disruption on that were working in the past
                       and one continuing to the present

John Playfair: further explained and supported Hutton's concept

Sir Charles Lyell: proved beyond reasonable doubt the idea of geologic evolution through
                          his book Principles of Geology

GENETICS

Mendel's Princples of Inheritance

1. The F1 generation showed only dominant traits
2. In the F2 generation, both the dominant and recessive traits reappeared
3. In the F2 generation, there were 3x as many plants with the dominant traits than plants with recessive traits

LAW OF SEGREGATION
          - Mendel inferred that the two factors determining a trait segregates when the sex cells are formed
          - Each gamete (egg cell or pollen) is equally likely to contain either traits
phenotypes: trait of a plant (tall)
genotypes: the pair of alleles for that trait (TT or Tt)

LAW OF DOMINANCE

LAW OF INDEPENDENT ASSORTMENT
          - alleles of the gene pair for a particular pair of traits segregate independently of the alleles of gene pairs for the trait

MEIOSIS

MEIOSIS
          - type of cell division involving reproductive cells

Phases

Meiosis I
     stages:

Prophase I

• two sister chromatids of each chromosome pair up with the chromatids of its homologue (synapsis)
• makes up 90% of the entire process
• forms a structure called tetrads
• chromatids of homologous chromosomes exchange segments (crossing-over)
• nucleoli and nuclear membrane start to disappear

Metaphase I

• homologous chromosomes align at the middle of the cell

Anaphase I

• movement of the chromosomes of each homologous pair toward the opposite poles of the cell
• individual chromosome still consist of two sister chromatids

Telophase I and Cytokinesis

• chromosomes are on each side of the pole
• chromosome still consist of two sister chromatids
• nucleoli and nuclear membrane reappear

Meiosis II
     stages:

Prophase II

• starts with haploid cells
• nuclear envelope starts to breakdown

Metaphase II

• chromosomes line up along the cell equator

Anaphase II

• chromosomes are pulled toward the opposite poles of the cell

Telophase II

• chromosomes finish their migration to poles
• nuclear membrane forms again and nucleolus reappear

Cytokinesis

• four new daughter cells are produced, each with a haploid number of chromosomes

MITOSIS

VOCABULARY :

• Cell Division - process by which cell reproduce
• Chromosomes - cell parts that determine what traits a living thing will have
• Chromatid - one strand of DNA, after replication, a chromosome is made up of two identical chromatids
• Daughter Cells - new cells produced by cell division
• Cytokinesis - a division of the cytoplasm of one parent cell into two daughter cells

Interphase
          - DNA has replicated but has not formed the condensed structure of chromosome. They remain as loosely coiled chromatin. The nuclear membrane is still intact to protect the DNA molecules from undergoing mutation.
   G1
   S - synthesis (DNA)
   G2

Early Prophase
          - the nuclear membrane breaks down
          - chromosomes shorten and thicken
          -centrioles are forming

Late Prophase
          - centriole pairs move apart
          - nuclear envelope starts to break up

Metaphase (midddle)
          - the chromosomes are lined up along the cell's equator
          - are attached to the mitotic spindle

Anaphase (away)
          - the newly formed chromosomes are pulled toward opposite poles of the cell

Telophase
         - the chromosomes have finished their migration to the poles
         - the plasma  membrane of the cell pinches down along the equator
         - the nuclear membrane forms again and the nucleolus reappears

Cytokinesis
         - after mitosis, two diploid daughter cells have formed
  

Fermantation

FERMENTATION

• is the breakdown of pyruvic acid without the use of oxygen
• no ATP produced
• alcoholic and lactic acid

Alcoholic Fermentation
          - occurs in plant cells and some one-celled organisms (yeasts)
pyruvic acid + NADH + H ----------> CH3CH2OH + CO2 + NAD (returns to glycolysis)


Lactic Acid Fermentation
          - takes place when there is a short supply of oxygen in cells
pyruvic acid + NADH + H ----------> Lactic Acid + NAD (reused in glycolysis)


AEROBIC RESPIRATION

• large amount of energy is released from a glucose molecule
• takes place in the matrix and cristae (mitochondrion)
• occurs as a series of chemical reaction in which oxygen is used to convert the chemical energy stored in a organic food molecule to ATP and reduced H2 acceptor
• has 3 stages :

                                 - conversion of pyruvic acid to acetyl-CoA
                                 - Krebs cycle or Citric Acid Cycle
                                 - electron transport chain

1. Conversion of Acetyl-CoA
          - happens instead of lactic acid fermentation when you have enough oxygen
P.A. + CoA + NAD ----------> Acetyl-CoA + CO2 + NADH  + H
          1 glucose molecule = 2 molecules of Acetyl-CoA
          1 glucose molecule = 2 Pyruvic acid
                 1pyruvic acid  = 1 Acetyl-CoA


2. Krebs Cycle
          - From Sir Hans Adolf Krebs
          - The central biochemical pathway of aerobic respiration
          - Also called citric acid  cycle
          - Occurs in the inner matrix of the mitochondrion
          - Consists of :
                    - Dehydration (removal of water)
                    - Hydration (addition of water)
                    - Decarboxylation (removal of carbon dioxide)
                    - Dehydrogenation (removal of hydrogen)


3. Electron Transport Chain
         - oxidative phosphorylation
         - The breakdown of glucose is complete
         - 4 new ATP molecules are made
         - involves cytochromes (class of proteins that fuctions as electron transporter)
         - water is a by-product

CELL RESPIRATION

GLYCOSIS
          - the conversion of glucose into a reactive compound, pyruvic acid
          - occurs in the cytosol
          - has 4 major stages

                                                           GLUCOSE
                                                                   | phosphorylated
                                                                   |
                                                       Glucose-6-phosphate
                                                                   |
                                                                   |
                                                        Fructose-6-phosphate
                                                                   |
                                                                   |
                                                     Fructose1, 6 Diphosphate
                                                                 /  \
                                                                /    \
                                                               /      \
                                                              /        \
                                                       PGAL     PGAL
                                                        (3-C)      (3-C)
                                                            |              |
                                                         +P            +P
                                                           |               |
                                             Pyruvic Acid     Pyruvic Acid

PHOTOSYNTHESIS II

PHOTOSYNTHESIS

Two Raw Materials
          - Carbon Dioxide - stomata
          - Water - xylem vessels

                     CO2 + H2O + light ------------> C6H12O6 + H2O 

Two Processes

• Light Dependent or Photolysis
• Light Independent or Dark Reaction

LIGHT DEPENDENT
          - also called photolysis
          - occurs in the thylakoids
          - involves: Photosystem I
                          Photosystem II

Photosystem I
          - reaction center is 700
          - far-red region
          - more in chlorophyll a

Photosystem II
          - reaction center is 680
          - red region
          - in chlorophyll a and chlorophyll b

LIGHT ENERGY --------> chlorophyll a
                                (electrons excited)(P680)
                                                   |
                                                   |
                                      energized chlorophyll
                                                   / \
                                                  /   \
                                  splits water    adds P1
                                         / \                |
                                        /   \               |
                                     2H  O2     ADP(energy carrier)
                                       |                    |
                                       |                    |
                       NADP(H acceptor)    ATP
                                       |                    |
                                       |                    |
                                 NADPH          energy   
                                         \                   /
                                           \               /
                                    DARK REACTIONS

LIGHT INDEPENDENT
          - dark reactions
          - Calvin-Benson reaction
          - carbon fixation
          - occurs in the stroma

                                                      CO2
                                                          |
                                                          |
                                                   RuDP(CO2 acceptor)
                                                          |
                                                          |
                                           6-C sugar (very unstable)
                                                          | splits
                                                          |
                                 2 mols. of PGA (3 carbon compound) 
                                                          | combine
                                                          |    with
                                 2H from NADPH (from Light Reaction)
                                                        / \
                                                       /   \
                                                      /     \
                                             PGAL    H20 released as by products
                                                / \
                                               /   \
                                      RuDP    Glucose

External Factors that Affect Photosynthesis

1. light
2. Carbon Dioxide
3. temperature
4. water supply
5. minerals

Internal Factors

1. leaf structures
2. amount of photosynthetic products
3. enzymes    

PHOTOSYNTHESIS

PHOTOSYNTHESIS
          - a complex process that uses light energy to convert carbon dioxide and water into carbohydrates.


Discoveries on Photosynthesis


Jan van Helmont
          - Flemish botanist
          - first who studied photosynthesis
          - on 1630 he concluded that plants make their own organic materials and donot get these from the
             soil. 


Joseph Priestly
          - in 1772, he showed that a sprig of mint would restore air that had been injuredby a burning
            candle.
          - the results showed that oxygen gas, which is used up in burning, is released by plants.


Jan Ingenhouz         
          - supported the findings of Priestly
          - in 1779, he added that this air (oxygen) could only be restored by plants with sunlight.


Nicholas de Saussure
          - in1804, he made an experiment and its results showed that the increase in the dry weight of the plant
           was greater than the weight of the carbon dixide removed from the air.
          - concluded that aside from carbon dioxide, the other substance that contributed to the increase in the
           weight of the plant was water.


C. B. van Niel
          - in the 1930s, he was able to proved that light splits water, producing oxygen.


General Outline of Photosynthesis
carbon dioxide + water + light energy ----> organic material + oxygen + water


2 CLASSIFICATIONS


Heterotrophs
          - also called as "other-feeders"
          - cannot synthesize their own food and depend on autotrophs


Autotrophs
          - also called as "self-feeders"
          - synthesize their own food
          - has 2 main types:
               : photoautotrophs - include green plants and purple bacteria
               : chemoautotrophs - includes bacteria

 OXIDATION-REDUCTION PROCESS or REDOX REACTIONS
                     - involve the stable transfer of electrons between atoms.
It is said to be:

     Reduced - when an atom gains one or more electrons
     Oxidized - when it loses one or more electrons

CELLULAR TRANSPORT

Cellular Transport

2 Kinds:

ACTIVE TRANSPORT
          - requires energy
Examples:
     Sodium-Potassium pump
     Bulk Transport

Bulk Transport

Endocytosis
     - engulfs
     - 3 kinds:

Phagocytosis
     - solid
Pinocytosis
     - liquid
Reverse Mediated Endocytosis
     - specific molecules

Exocytosis
     - reverse


PASSIVE TRANSPORT
          - does not requires energy
          - 2 kinds:

Diffusion
     - movement of molecules from an area of high concentration to an area of low concentration

Factors Affecting the Rate of Diffusion

1. Size of the diffusing molecule
2. Molecular weight of the diffusing substance
3. Structure and composition of cell
4. Concentration gradient
5. Temperature
6. Other external factors

Osmosis
     - the diffusion of water through a semipermeable membrane

hypotonic - the cell bursts
hypertonic - the cell shrinks
isotonic - nothing happens to the cell  

PROKARYOTIC CELLS and EUKARYOTIC CELLS

Prokaryotic Cells

          - Greek, pro 'before' and karyon 'kernel'
          - unicellular organisms
          - lack nucleus and other membrane-bounded structures
          - bacteria and blue-green algae
          - DNA is coiled into a nucleus-like region(nucleoid)


Eukaryotic Cells

          - Greek, eu 'true' and karyon 'kernel'
          - plants, animals, protists, fungi
          - multicellular organisms
          - well-defined nucleus
          - DNA is bounded within a nucleus
          - with membrane-bounded organelles
          - with cytoskeleton

THREE BASIC PARTS of a EUKARYOTIC CELL

1. Plasma Membrane or Cell Membrane
2. Cytoplasm
3. Nucleus

CELLULAR STRUCTURES and FUNCTIONS

> The Cell Membrane

          - a thin layer of lipid and protein molecules held by noncovalent bonds
          - separates the cell contents from the surrounding medium
          - ranges from 5-10 nanometers
          - controls the entrance and release of substances in the cell
          - mainly composed of phospholipid molecules

PHOSPHOLIPID MOLECULE
          - composed of glycerol, two fatty acids, and one phosphate group
Polar or Amphipatic
          - 2 ends have different properties in water

• head - hydrophilic
• tail - hydrophobic

> The Nucleus

          - the control centre of the eukaryotic cell
          - surrounded by nuclear envelope (double layer)
          - contains the DNA
          - 2 main functions
               - directs chemical reactions in cells
               - acts as storage of genetic information and transfers such information

> The Cytoplasm

         - includes everything between the cell membrane and the nucleus
         - 2 main parts
               - Cytosol
                    - viscous colloidal substance of the cytoplasm
                    - where organelles are suspended
                    - site of major biological processes
               - Organelles

| THE ORGANELLES

Mitochondrion

• rod-shaped
• carries out process of cellular respiration
• "power-centre of the cell"
• has two compartments

           : Intermembrane Space
                 - inner and outer membranes
                 - highly folded (cristae)
           : Matrix

Endoplasmic Reticulum

• extensive network of membranes
• connects the nuclear envelope to the cell membrane
• 2 kinds :

      R.E.R

• has ribosomes attached on its surface
• makes more membranes
• transport proteins within a cell

      S.E.R.

• lacks ribosomes
• synthesizes lipids (fatty acids, phosholipids and steroids)

Ribosomes

• the protein factories of the cell
• attached to the E.R. (R.E.R.)

Golgi Apparatus

• from Camillo Golgi
• consists of a series of flat, membrane-bound sacs
• parallel to each other
• packages and secretes products of E.R.
• "packaging counter of the cell"
• one side receives from the E.R.
• inner sacs modify molecule
• other side transports out of the cell

Lysosomes

• is derived from the Greek word "breaking body"
• "suicidal bags of the cell"
• fuse with food vacuoles and digest the cell contains with the enzymes

     Lysosomal Storage Disease

• Pompe's Disease - accumulation of glycogen
• Tay-Sach's Disease - accumulation of lipids

Vacuoles

• fluid-filled cavities in the cytoplasm containing crystals, inorganic salts, sugars, insoluble particles, and excess water
• bounded by a membrane
• usually acts as storage organelles

Food Vacuoles
Contractile Vacuoles

In Plants:
     Centarl Vacuole - for growth
- contain pigments that attract insects
- contain toxic substances to protect from plant-eating insects

Peroxisomes
     - catalase
              - breaks down hydrogen peroxide
Hydrogen Peroxide
     - very toxic
     - product of cellular metabolism

ORGANELLES PECULIAR TO PLANT CELLS

1. Cell Wall
          - protection
          - 3 layers : primary layer
                              middle lamella
                              secondary layer
2. Plastids
          - pigment-containing storage organelles
Chloroplasts: red, yellow, green, violet, orange
Leucoplasts: colorless

Thylakoids  - disk-shaped structures
                     - stroma
                     - grana 

CELLS

THE CELL THEORY

Zacharias Jansen (1588-1631)
- invented one of the microscope's first prototype

Robert Hooke (1635-1703)
- reported some clear drawings of the plant cells
- introduced the term cell after observing boxlike structures from cork slices

Anton van Leeuwenhoek (1632-1723)
- reported the discovery of blood cells, sperm cells

*FORMULATED AFTER 200 YEARS AFTER THE INVENTION OF MICROSCOPE

Lorenz Oken (1779-1851)
- postulated that all organisms originate from and consist of cells

Robert Brown (1773-1858)
- discovered the nucleus

Felix Dujardin (1801-1860)
- sarcode, living substance within the cells was discovered (1835)
- the term was changed to protoplasm by Jan Evangelista Purkinje (1787-1869)

Matthias Schleiden (1804-1881)
- said that plants are made up of cells

Theodore Schwann (1810-1882)
- said that animals are made up of cells

Rudolf Virchow (1821-1902)
Concluded that
- the cell is the basic and structural unit of life
- every cell is formed from pre-existing cell


THREE PRINCIPLES OF THE CELL THEORY

• All organisms are composed of one or more cells
• Cells are the basic unit of organization of all organisms
• Cells arise only by division of a previously existing cell

CHEMICAL COMPOUNDS IN THE LIVING SYSTEM

Compounds
- a bigger molecule formed by atoms

2 Main Groups

Organic Compounds
- compounds that contain carbon atoms bonded to hydrogen or oxygen atoms

Inorganic Compounds
- compounds that lack carbon atoms


Inorganic Compounds

Water HOH
- 2/3 of our total body weight is water
- universal solvent

Acids
- releases one or more hydrogen ions (H+)
ex:
Hydrochloric acid (HCI)
Sulfuric acid (H2So4)

Base or Alkaline
- releases one or more hydroxyl ions (OH-)
ex:
Sodium hydroxide (NaOH)
Ammonium hydroxide (NH4OH)

pH Scale
- measures how acidic or how basic a substance is.
0-6 : substance is acidic
ex: battery acid
7 : neutral
ex: water
8-14 : substance is basic
ex: baking soda

buffers - resist changes in the pH of the chemical system
*Important Biological Buffers
- bicarbonates
- phosphates
- organic molecules (amino acid)

Salts
- form when an acid and a base react.
- hydrogen ion+hydroxyl ion = salt (table salt)+water

Neutralization Process - positive ion of an acid reacts with the negative ion of a base


Organic Compounds

Carbohydrates : compounds contaning carbon, hydrogen, and oxygen in the ration of 1:2:1

Monosaccharides - simplest form of carbohydrates
- glucose, fructose, and galactose are examples

Glucose
- most common hexose in the body
- sometimes reffered to as blood sugar, dextrose, and grape sugar
- indespensable component of blood

Fructose
- sugar that accounts for the sweeteness of ripened fruits

Galactose
- monosaccharides found in milk

Five-carbon sugars (pentose)

Ribose
- important component of ribonucleic acid (RNA)
Deoxyribose
- important component of deoxyribonucleic acid (DNA)


Disaccharides
- reffered to as the double sugars
- made up of two monosaccharide units
Dehydration Synthesis
- formation of a disaccharide from 2 monosaccharide units with the
removal of a water molecule

Examples:

Maltose (malt sugar)
-formed by the reaction of 2 glucose units

Sucrose
- common table sugar
- formed by the reaction of one molecule of glucose and one molecule of fructose

Lactose
- milk sugar
- formed when one molecule of glucose reacts with one molecule of galactose

Polysaccharides
- composed of a large number of monosaccharide units

Starch
- common component of plant protoplasms
- soluble in water

Glycogen
- found in bodies of animals
- excess glucose units stored temporarily

Cellulose
- similar to starch
- insoluble in water
- part of the plant cell wall


Lipids : composed of carbon, hydrogen, and oxygen but contain much less oxygen in proportion to carbon and hydrogen

2 Basic Units

Glycerol
Fatty acids

2 Kinds of Fats

Saturated Fats
- are solid at solid temperature
- examples are butter, lard, and animal fats
- promotes a condition called atherosclerosis

Unsaturated Fats
- remain liquid at room temperature
- not harmful to one's health
- examples are corn oil, olive oil , and other vegetable oils.


Proteins
- most diverse in the structure and function among organic compounds

peptide bond - formed between the amino group of amino acids and the carbon group of the next
amino acid.

Classes of Proteins

a. Structural Protein e. Transport Protein
b. Contractile Protein f. Hormonal Protein
c. Storage Protein g. Receptor Protein
d. Defensive Protein h. Catalytic Protein


Nucleic Acid
- serve as blueprints for proteins that ultimately control the chemical processes in a cell.
- nucleotide is composed of a five-carbon sugar, a phosphate group, and a
nitrogen-containing base pair.

THE LIVING CONDITION

THEORY OF SPONTANEOUS GENERATION



Spontaneous Generation (Abiogenesis)

- believed that living things may arise from nonliving substances.



Aristotle

- noted in his book Historia Animalium: mullet, a kind of fish, is the mud

of a dried-up pond that came to life spontaneously when rain filled the pond.



John Turberville Needham

- English biologist

- boiled mutton gravy, poured into a glass vial, and corked it. After a afew days,

the gravy was swarming with microorganisms.



F.A. Pouchet

- respected French scientist

- prepared hay infusion and introduced "artificial air". In a few days, the infusion

contained a rich variety of microorganisms.





THEORY OF BIOGENESIS



Biogenesis

- states that life comes only from life



Francesco Redi

- Italian physician

- proved that maggots were not spontaneously generated from rotting meat.



Lazzaro Spallanzani

- Italian biologist

- repeated Neddham's experiment but failed to obtain growth of organisms

by spontaneous generation

- he used vessels that are tightly closed.



Louis Pasteur

- one of the graetest biologist of all time from France.

- made an experiment which proved that air was a source of contamination.

- used flasks for his experiments.



Stanley Miller

- proved in his laboratory the possibility of forming amino acids and other organic

molecules from a mixture of hydrogen, methane , and ammonia.



Characteristics of Living Things

• Living things have a specific organization
• Living things undergo metabolic processes in their bodies
• Living things can move
• Living things can react to stimuli or changes in their surroundings
• Living things are capable of growth
• Living things can reproduce
• Living things can adapt to their environment

THE SCIENTIFIC METHOD

Scientific Method
- a logical and orderly procedure of investigation

STEPS:

Making observations
- process of using our senses to describe things and phenomena

Formulating a hypothesis
- data gathered from a set of observations
- hypothesis is a possible and reasonable explanation for the question or problem

Testing a hypothesis
- experiment is a designed procedure used to test the validity of a hypothesis

SETS OF VARIABLES

• Independent Variable - factor tested in the environment
• Dependent Variable - factor measured to determine the outcome
• Controlled Variable - one that can influence the outcome of an experiment

GROUPS

• Control Group - all except the independent variable applied
• Experimental Group - all of the variable are applied

Observing and recording experimental data

• any result should be recorded
• may include notes, tabulations, and graphs
• everything should be recorded accurately

Drawing Conclusions

- must be entirely based on the results gathered from the experiment

Theory - a hypothesis that has been repeatedly and rigorouly tested

Law or Principle - when theory has been proven to be consistently true and has passed the test of time

IMPORTANT TOOLS IN BIOLOGY

Microscopes

- instrument that uses lenses to produce an enlarged and focused image of a specimen

2 Important Properties

Magnification- ratio between the image size and the object size

Resolution - refers to the smallest degree of separation

KINDS OF MICROSCOPE

Compound Light Microscope - focuses and bends light through a speimen to produce a magnified image

Stereomicroscope - also known as the dissecting microscope

- it has also lower magnification than that of the compound microscope. This is used for dissecting small specimens

Electron Microscope - uses a beam of electrons instead of light to create an image

• Transmission Electron Microscope (TEM) - uses a magnetic field beam to focus a beam of electrons through a thin section of the specimen. Can magnify the image of an object about 100 000 times
• Scanning Electron Microscope (SEM) - gives a surface view of a three-dimensional specimen. Can magnify the image of an object about 10 000 times
• Scanning Tunneling Microscope (STM) -allows viewing of atoms on the surface of a solid. It can magnify a specimen over 100 million times. It has a needle probe with a joint so sharp that only one atom is at its point,

OTHER SCIENTIFIC TOOLS

Ultracentrifuge - a machine used to separate suspended particles in a mixture

Chromatography - used in separating substances in a mixture

Electrophoresis - used to separate substances in a mixture according to how fast they move when subjected to an electric current

X-Ray Diffraction - very useful for the analysis of protein crystals using x-rays of a single wavelength.

Spectrophotometer - a device used to determine the amount of proteins or nucleic acid present in a solution

Computer - very useful in storing vast amounts of information. It is also used to organize data, make long and complex calculations, and make graphs

Life

Biology comes from the Greek words bios meaning "life" and logos meaning "study".

Biology is the study of life or the study of living things.

There are two major divisions of biology. These are:

• Botany - the study of plants
• Zoology - the study of animals

There are also several specialized fields in biology, these are:

• Anatomy - the study of the structures of organisms
• Cytology - the study of the structures and functions of cells
• Ecology - the studyof how organisms interact with their environment
• Morphology - the study of the gross structures and forms of organisms
• Genetics - study of how traits are inherited
• Histology - the study of tissues
• Molecular Biology - study of subcellular structures of the cells(DNA and RNA)
• Parasitology - study of organisms that live in or on other organism
• Physiology - study of how the body works
• Taxonomy - study of the classification and evolutionary interrelationship among organisms
• Evolutionary Biology - study of the origin and differentiation of organisms
• Embryology - study of the development and growth of an organism
• Paleontology - study of fossils, preserved remains and traces of organisms from the distant past
• Microbiology - study of microorganisms

HISTORY OF BIOLOGY

Aristotle (384-322 B.C.)

• famous Greek philosopher
• was the first to classify living things

Galen (A.D. 131-200)

• Greek physician
• described anatomy of the human body based on dissections of apes and pigs

Andreas Vesalius (1514-1564)

• made the first serious studies on human anatomy by dissecting corpses

William Harvey (1578-1657)

• English physician
• showed conclusively that the heart pumps the blood and the blood circulates

Marcello Malpighi (6128-1694)

• Italian physician and anatomist
• founder of microscopic anatomy
• in 1661, he discovered the capillaries

Anton van Leeuwenhoek (1632-1723)

• a cloth merchant
• first to use themicroscope with great observational and descriptive skills
• discovered microorganisms

Charles Darwin (1807-1882)

• an English naturalist
• his theory of natural selection suggested that we originated from apes
• his work provided a unifying, organizing framework for the field of biology