THE LIVING CELL

Discovery of the cell

Robert Hooke (1665) – examined a thin section of cork under the microscope and saw boxlike structure which were the outermost coverings of plant cell later called as cell wall.

Robert Brown (1830) – found the central part of the cell called the nucleus

Matthias Schleiden and Theodore Schwann found out that all living things are made up of cells

Rudolf Virchow discovered that exixting cells give rise to new cells.

Cell Theory states that:

1. the cell is the basic unit of structure and function in living organisms.
2. plants and animals are made up of one or more cells.
3. existing cells give rise to new cells

ANIMAL CELL

1. 

PLANT CELL

General Parts of the Cell:

1. nucleus – central part of the cell

nucleolus – contains the chromosomes; made up of DNA material and proteins which carry the hereditary information; synthesizes the ribosomes

nuclear membrane – separates the nucleus from the other parts of the cell

2. cytoplasm – semi-fluid substance in which the organelles are suspended
3. plasma membrane or cell membrane

v continuous double-layered membrane enclosing the cell

v made up of phospholipids molecules with proteins that are embedded within or located on the surface of the membrane

v selectively permeable or semi-permeable

cell wall – made up of cellulose which is responsible for making the plant cells rigid and sturdy

Cell organelles

1. golgi bodies

· modify proteins that are synthesized and packaged in endoplasmic reticulum

· facilitates transport of materials like glycoproteins

2. ribosomes – small granular structures involved in protein synthesis

2. endoplasmic reticulum

· smooth endoplasmic reticulum – branching canals and act as calcium ions reservoir in skeletal muscles

· rough endoplasmic reticulum – synthesize and packaged proteins which are sent to be synthesized in the golgi apparatus

· associated with ribosomes

4. mitochondria

· “powerhouse of the cell”

· This is where chemical energy of food such as glucose is converted into energy in the form of ATP (Adenosine triphosphate)

5. chloroplast – contains green pigment chlorophyll which is used to convert light energy to ATP

5. lysosomes

· “suicide bags” of the cell”

· Digest complex nutrients and broken down organelles

7. centrosomes / centrioles – duplicate during interphase and prophase and move apart

7. cytoskeletons - “bone and muscle” of the cell

a.) microtubules – skeletons of cells; help provides anchorage for organelles in the cell

b.) intermediate filaments – give support to the cytoplasm of cells; detect some disaorders

c.) microfilaments – muscles of cells; give shape to the cell and are involved in the construction of cytoplasm during mitosis

9. Vacuoles – serve as storage of food and water

Unicellular – single-celled organisms and can survive in their own

Multicellular – different kinds of cells exists; all cells carry on the basic activities of life; each kind of cell often specializes in a particular function in addition to itas basic activities.

Colonial – made up of similar cells; cells are organized into working unit different from individual cells

Prokaryotes

• organisms where the cells have no true nucleus and lack some organelles
• nuclear materials are not enclosed by a nuclear membrane
• the DNA is a single circular structure (plasmid)
• do not have mitochondria, endoplasmic reticulum, lysosomes, vacuoles and golgi bodies; ribosomes are small
• examples are bacteria and blue-green algae

Eukaryotes

• have well-defined nuclear membrane and distinct nucleus
• multiple chromosomes are present and can be seen during cell division
• membrane-bound organelles can be found
• division of labor among organelles enabled them to be multicellular and grow larger than prokaryotes

MICROSCOPE

All biologists used things such as balances, dissecting tools and computers. One of the most important tools is the MICROSCOPE.

A microscope is an instrument used to study objects too small to be seen and observed by the unaided eye. It greatly increases the amount of data available for scientific inquiries.

The hand lens has been around for over 600 years and is considered as a simple microscope. The first microscope was invented in 1595 by Zacharias and Hans Janssen.

Janssen’s microscope composed of three draw tubes with lenses inserted into the flanking tubes.

Janssen’s microscope was capable of magnifying images approximately 3x when fully closed and up to 10x when fully extended to the end.

— Anton Van Leeuwenhoek further developed the microscope to different shape and magnification.

— His microscope could magnify up to 300x.

— He was the first to view protozoans and bacteria.

Robert Hooke's microscope is the microscope used in discovering the cell.

Kinds of Microscope:

1. Light microscope – uses light to form an enlarged image of the specimen or object being viewed.

a.) simple microscope – single lens or curved piece of glass

b.) compound light microscope – contains two kinds of lenses, the ocular and objective lenses

v Magnification – apparent increase in the size of an object

v Resolving power – ability of a microscope to increase the visible detail of a specimen.

c.) stereomicroscope – used to study large specimens; has an ocular lens and

objective lens for each eye

- arrangement of lenses provides a three-dimensional view of

the specimens surface magnified 50 to 60 times

d.) phase-contrast microscope – clarifies features inside living cells

- special lenses of this microscope use this

interference to reveal boundaries between cell parts,

which appear brighter to the viewer

2. Electron Microscope

- creates enlarged images with a beam of electrons instead of a beam of light

- introduced by the scientists in 1935

- produced both high magnification and high resolution

2 kinds of electron microscopes:

a.) transmission electron microscope – sends beam of electrons through the specimen; the beam creates a clear detailed image on a television like screen magnified 200,000 times or more

b.) scanning electron microscope – sends beam of electrons across the specimen from left to right, a process called scanning

Parts of a Compound Microscope:

1. arm – supports the body tube
2. ocular or eyepiece – contains the magnifying lens you look through
3. body tube – maintains the proper distance between the eyepiece and the objective lenses
4. revolving nosepiece – holds the high and low power objective lenses and can be rotated to change magnification.
5. objective lenses

low power objective (LPO) – provides 10x magnification

high power objective (HPO) – provides 40x magnification

6. stage clips – hold the slide in place
7. stage – supports the slide being viewed
8. diaphragm – regulates the amount of light
9. mirror – reflects the light
10. base – supports the microscope
11. coarse adjustment knob – moves the body tube up and down
12. fine adjustment knob – moves the body tube slightly to sharpen the image

Click here for additional informations about the microscope.

SELF-TEST

1. What is a microscope?

2. What is a compound microscope?

3. What are the lenses on a microscope called?

4. How should a microscope be carried?

5. How is the total magnification of a microscope determined?

6. What is the purpose of the mirror and diaphragm?

7. What is the purpose of the adjustment knob?

8. What do the clips hold?

9. What is magnification? resolution?

BIOTECHNOLOGY

Biotechnology is the use of microorganisms and utilization of biological systems or processes to convert organic materials into food, medicine, industrial chemicals and a variety of other products.

Molecular biology is the study of organisms at the molecular level. It deals with identification of the structure and composition of DNA molecules.

Technology is the application of science to serve the needs of people. Investigations conducted are meant to apply science principles to make living more convenient.

Technological Breakthrough:

1. rapid composting method using microorganism called Trichoderma harzianum
2. Biogas which is a fuel produced by anaerobic decomposition of organic matter by microorganisms.
3. increased production of fruits like mangoes through flower induction using potassium nitrate
4. tissue culture which increased the production of some plants like macapuno, orchids and forest trees
5. selective breeding and hybridization to increase growth rate and improve resistance and tolerance to a variety of diseases

Biotechnology Application:

1. Health and medicine

v Aided medical research in finding new and more effective cures for serious diseases and developing diagnostic tools to detect diseases in their early stages.

v Studies deal with preparation of drugs from crude plant materials and from semi-pure and pure plant constituents.

Examples:

Lagundi – remedy for fever sambong – for cough

Tsaang gubat- antidiarrhea Yerba Buena – pain reliever

Malunggay – increase milk secretion for lactating mothers

2. Food

v Lactobacillus delbruechii – hasten the fermentation of soy sauce

v Mongo is a good substitutes of soybeans in soysauce

v Protease, a product of fungal species Aspergillus oryzae, helps accelerate the aging time of bagoong and patis.

v Acetobacter aceti sp. xylinum is a bacteria used in nata-making

v Pineapple juice and rice washings can also be substitutes in nata-making

3. Dairy Products

Lactobacillus acidophilus is used in the production of sour milk and cottage cheese

SCIENTISTS IN THE FIELD OF BIOLOGY

FOREIGN BIOLOGISTS

1. Gregor Mendel – an Austrian monk; father of heredity and the basic laws of inheritance
2. Louis Pasteur – French chemist and microbiologist; father of bacteriology; developed vaccine against rabies
3. Rudolf Virchow – German medical naturalist; father of modern pathology; contributed to the cell theory
4. Charles Darwin – British naturalist: worked on the theory of evolution and natural selection
5. Sir Alexander Flemming – Scottish bacteriologist; discovered penicillin as an antibiotic
6. William Harvey – English physician; discovered the mechanics of human blood circulation
7. Robert Koch – German microbiologist discovered bacteria causing anthrax, tuberculosis and cholera
8. Carolus Linneus – Swedish naturalist and botanist father of taxonomy
9. Joseph Lister – British medical doctor and surgeon highlighted the importance of antiseptic in surgery
10. Edward Jenner – worked on smallpox vaccine
11. Anton Van Leeuwenhoek – Dutch naturalist; designed compound microscopes with high magnification which led to microbiology
12. Albert Sabin – discovered vaccine against polio virus
13. Robert Hooke - gave the name “cells” for the structure he saw under the microscope
14. James D. Watson – American biologist; described the double helix structure of DNA
15. Francis H.C. Crick – British biophysicist; described the doubled helix structure of DNA

FILIPINO BIOLOGISTS

1. Eduardo A. Quisumbing, Ph. D. – pioneered in the study of medicinal plants; Father of Philippine Orchidology
2. Carmen c. Velasquez, Ph. D. – identified numerous species and genus of parasitic organisms, particularly fish parasites
3. Gregorio T. Velasquez, Ph. D. – produced 45 researches and 70 articles on algae
4. William G. Padolina, Ph. D. – pioneered excellent researches in biotechnology and chemistry of natural products
5. Emerita V. De Guzman, Ph. D. – recognized for her research on propagation of mutant macapuno and tissue culture technique for rapid propagation of abaca and banana
6. Angel C. Alcala, Ph. D. – known for conservation of coral reefs, mangroves, aquaculture studies in giant clams, mollusks and fishes
7. Ramon C. Barba, Ph. D. – Known for mango flower induction technology, tissue culture of sugarcane, rattan and banana and development of seedless kalamansi
8. Priscillano M. Zamora, Ph. D. – published articles on morphology and taxonomy of some crop plants, ferns and gymnosperms
9. Pedro B. Escuro, Ph. D. – gained international recognition for developing the dwarf high yielding C rice varieties
10. Germiniano T. De Ocampo, Ph. D. – pioneered in modern ophthalmology and led corneal transplantation in the country.

THE SCIENTIFIC METHOD

Scientific method is a logical procedure in solving problems.

Pure science involves the search for new knowledge while applied science (technology) puts the findings of pure science to practical use.

Steps in Scientific method:

1. Defining the problem

Ø The scientist could find information in books and scientific journals, use computer to search for scientific information published each year.

2. Formulating a hypothesis

Ø A hypothesis is a proposed answer to the question which can be based on the information available to the scientist.

Ø It can be an educated guess or a statement that can be tested.

3. Testing the hypothesis

Ø A hypothesis can be tested in an experiment.

Ø A variable is the factor tested or investigated in an experiment.

Ø An independent variable is the condition that is varied. It is the factor that causes changes in the result.

Ø Dependent variable is the condition that respond to the changes in the independent variable.

Ø There are two identical groups of subjects in an experiment.

a.) experimental group – exposed to the changes in the independent variable.

b.) Control group – not exposed to the changes in the independent variable.

Ø Controlled experiment is an experiment that uses both control and experimental group.

4. Making and recording observations

Ø In order for an experiment to be reproduced by other researchers, a scientist must keep records which states how an experiment was planned, what equipment was used and how long it took.

Ø Information about the experiment must include all observations made together with tables, graphs, diagram, drawings and photographs.

5. Drawing conclusions

Ø Conclusion is considered an answer to a scientific question.

Ø Data are scientific facts collected during the experiment.

Ø Statistics is a mathematical method of evaluating numerical data. This helps determine whether important differences exists between data obtained from experimental and control group.

Ø Before accepting conclusion, scientists retest their hypothesis several times.

Ø A scientific principle or law is a hypothesis that explains how an event occurs.

Ø A theory is a hypothesis that explains why events occur.

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BRANCHES OF BIOLOGY

What is Biology?

Biology is the study of life. As we study biology, we will frequently run across a lot of “big words” that you will need to learn. One thing that can help you understand those words, which will also aid you in everything from reading the newspaper to communicating with your doctor, is to know the Greek or Latin (or other) derivations of the wordstems which make up those words. For example, the word “biology” is made from the wordstems bios, which means “life,” and -logy which means “to study” or “the study of.”

Anatomy: the study of the structure of organisms

Botany: the study of plant life

Biochemistry: the study of the chemistry or chemical compositions of living things

Cytology: the study of the structure, function, multiplication, pathology, and life history of cells

Ecology: the study of the relations of living things to their environment

Embryology: the study of the development of organisms

Entomology: the study of insects

Genetics: the study of heredity and variation of organisms

Histology: the study of the minute structures of plant and animal tissues

Ichthyology: the study of fishes

Microbiology: the study of microscopic forms of life

Mycology: the study of fungi

Ornithology: the study of birds

Parasitology: study of parasites

Paleontology: the study of the life of past geological periods as known from fossil remains

Pathology: the study of the nature of diseases and the structural and functional changes produced by them

Phycology: the study of algae

Physiology: the study of the functions of living organisms and their parts

Taxonomy: the study of the description, identification, naming and classification of organisms

Virology: the study of viruses

Zoology: the study concerned with the animal kingdom and the lives of its members as individuals and classes

CHARACTERISTICS OF LIFE

I. Some Definitions of Life:

Life: The property manifested in functions such as metabolism, growth, response to stimulation, and reproduction, by which living organisms are distinguished from dead organisms or from inanimate matter. (Webster's Dictionary)
Life: The state of being which begins with generation, birth, or germination, and ends with death; also, the time during which this state continues; that state of an animal or plant in which all or any of its organs are capable of performing all or any of their functions; used of all animal and vegetable organisms. (Gray's Medical Dictionary)

II. What Properties are Associated with Life? Life is difficult to define, but all living organisms are alike in these aspects:

1. Cellular Organization: All living organisms are composed of one or more cells - the basic unit of life ... "Life is Totally Cellular"
2. Growth and Development: All living organisms assemble matter (chemical elements) into simple or complex compounds, and use the energy derived from these compounds to grow and change over time. The process of using chemical energy to do cellular work is called metabolism.
3. Reproduction: All living organisms are programmed to produce new generations of cells or new multicellular organisms.
4. Response to Environment: All living organisms sense changes in their surroundings (using receptors) and make controlled responses (behavior).
5. Heredity: All living organisms possess a genetic system that is based on the replication of DNA, a complex double-stranded molecule that specifies the information to make cellular proteins.

III. Life is organized on many structural levels: At each level of organization, novel properties emerge that were not present at the previous level.

Biosphere - regions of air, water and soil on Earth where living organisms exist
Ecosystem - a community and its physical environment
Community - groups of different species living in the same area
Population - groups of individuals of the same species living in the same area
Multicellular Organism - an individual composed of cells arranges into tissues and organs
Organ System - groups of organs performing a common task
Organ - groups of tissues performing a common task
Tissue - group of specialized cells
Cell - Smallest living unit
Organelle - compartments inside cells
Molecule - 2 or more atoms bonded together
Atom - smallest unit of an element
Subatomic Particle - proton, electron, neutron


IV. Classifications of Life


There are at least 5 million and perhaps 10 - 30 million species on Earth!
6 to 7 million in tropics alone1.4 million species currently named and described260,000 plants, 50,000 vertebrates, 750,000 insects....


1. Kingdom Monera [10,000 species]: Unicellular and colonial-- true bacteria (eubacteria), archaebacteria*, and photosynthetic cyanobacteria (blue-green algae).
























2. Kingdom Protista [250,000 species]: Unicellular protozoans and algae (unicellular & multicellular)




















3. Kingdom Fungi: [100,000 species] Multicellular, generally heterotrophic mushrooms, molds, and fungi

4. Kingdom Plantae: [250,000 species] Multicellular photosynthetic organisms

5. Kingdom Animalia: 1,000,000 species] Multicellular animals, without cell walls and without photosynthetic pigments

*Currently 5 different Kingdoms are recognized; however, many scientists believe that the prokaryotic Archaebacteria belong in their in their own (6th) Kingdom

However, even with all this diversity.....all forms of life show unity in that they are all
Are based on the cellUse the same genetic code (DNA)Share similar or identical metabolic pathwaysShare similarities of cell structure