Cell Structure and Function

Cell Structure and Function

Biology II

Cell - The basic unit of life. Also considered as the smallest independent living unit of all living organism. This consist of a

plasma membrane surrounding a microscopic amount of Jelly-like cytoplasm.

Cell Theory

All living things are made up of cells. Some organisms are unicellular, made up of only one cell. Some unicellular organisms may be held together by a matrix or biding materials to form a colony. Other organisms are multicellular, composed of countless number of cells. The life of even the most complicated multicellular organism still starts from a cell - a fertilized egg or zygote. A zygote divides into two, and each newly formed cell subdivides. Further divisions of cells occur continuously until a multitude of cells organize into tissues, tissues into organs, and organs into organ systems of a multicellular organism. The complex life processes which sustaining reactions which the single cell of unicellular organism performs. These are the biological concepts that comprise the so-called 'cell theory'. Basically, the concepts may be summarized into three statements as follows:

1. All living things are structurally made up of cells.

2. The cell is the fundamental unit of life.

3. Cells come from the division of preexisting cells.

The cell theory is one of the most important concepts in biology. The three statements answer three important questions about life.

What are living things made of?

What can cell do?

Where do cells come from?

With an estimated five million species of diverse organisms worldwide, it is amazing to know that they all share a common characteristic, their cellular structure.

How was the cell theory developed?

The cell theory was the product of the work, not of one, but of many biologists of various nationalities through a long span of about three centuries.

1. ROBER HOOKE (1635 - 1703) an Englishman coined the term cell and was responsible for the beginnings of cytology as a sub discipline in biology.

2. ANTO VAN LEEUWENHOEK (1632 - 1723), Dutch naturalist, discovered bacteria and other microscopic organisms in rainwater and studied the structure of plant and animal cells.

3. FRANCESCO REDI (1627 - 1697) and LAZZARO SPALLANZANI (1729 - 1799), Italian physician and biologist, respectively, disproved the Theory of Spontaneous Generation.

4. ROBERT BROWN (1773 - 1858), a Scottish botanist, discovered the presence of nuclei within cells.

5. FELIX DUJARDIN, a Frenchman, noted that all living things contain a thick jelly fluid which he called sarcode at that time.

6. MATTHIAS SCHLEIDEN (1804 - 1881) and THEODOR SCHWANN (1810 - 1882), German botanist and zoologist, respectively, introduced the concept that all plants and animals are made up of cells.

7. JOHANNES PURKINJI (1787 - 1869), a Czechoslovakian, coined the tem protoplasm to refer to the living matter of the cell.

8. RUDOLF VIRCHOW (1821 - 1902), a German physician, found that cells divide to form new cells. He concluded that

"omnis cellula e cellula" or cells come from preexisting cells.

9. LOUIS PASTEUR (1822 - 1895), a French chemist, supplied the proof for Virchow's Theory of biologist.

3 Fundamental Parts of Cell

1. Cytoplasm - The region where the main metabolic life activities takes place.

2. Cell Membrane - Protectively surrounding the cytoplasm.

3. Nucleus - the region where the genetic material is located.

Cell Structure and Function

Biology II

Prepared By: Mr. Matthew T. Sabasales

Basic parts of the Cell

1. Cell Wall - Serves to protect the cell, commonly found among plant cell and bacterial cells. It is compared to a protective fence.

2. Plasma Membrane - Also called cell membrane, works in the control of the entrance and exit of substances to and from the cell. It is being compared to a security Guard.

3. Nucleus - The command center of the Cell . Functions in the regulation and coordination of all activities of the cell.

4. Nucleolus - Found inside the Nucleus, Responsible for the synthesis of Ribosomes.

5. Chromosomes - Transmits genetic traits from generation to generations.

6. Vacuoles - Water storage facility