In 1668-1677,, Anton Van Leeuwenhoek made a better microscope. Thus, Leeuwenhoek could describe a lot of thing, such as the protozoa he found in the pound and the speciments taken from the teeth. By this invention, Leeuwenhoek has been the first person who could see the bacteria.
The next two centuries, no one relized the meaning of cell, until in 1839, two German botanist and zoologist, Matthias Jacob Schleiden and Theodore Schwann revealed the theory of cell. This theory provided a new point of the biologist in studying living organism.
Cell cannot be separated from microscope because cell can only be seen through microscope. The simplest modern microscope is light microscope.Light microscope works by passing the light througt the object observed. In the microscope, the light will be deflected by the lens to from larger shadows of the real objects. This virtual object is, then projected to the eyes, so that the observer could see the object clearly.
Besides being observed directly, the observation result could be printed.Those printing is called micrograph. Light microscope can enlarge the virtual image of the object up to 1.000 times.
Mocroscope was continued to develop so that the enlargement grew bigger as well. In 1933, a German Physicist, Ernst Ruska, Succeeded in making the first electron microscope. This microscope is called TEM (Transmission Electron Microscope). TEM microscopes can only be used to observe non-living objects. TEM microscopes could enlarge the virtual image of the objects observed up to 500.000 times. After TEM, microscope continued to developed until in 1965, SEM (Scanning Electron Microscope) was succesfully made. Using SEM, we can see the detail architecture of cell surface in 3D figure.
In 1981, a microscope with up to 1.000.000 times enlargement was made. It was called STM (Scanning Tunneling Microscope). STM measured the missing electrons frome specimen’s surface. By STM, the scientists could see each molecule in the outer layer of cell.
B.STRUCTURE OF CELL
1.Theory of Cell
In 1885, a German physiologist, Rudolf Virchow made new dicovery on cell divition bringing the theory of the cells one step ahead. Virchow stated that new cell can only be produced from the existing cells. This theory has failed the theory of spontaneity, which stated that living organism cell was originated from non-living material. The conclusions about cell made by Schleiden, Schwann, and Virchow along with the prvious observations made by Hooke and Leeuwenhoek summarized in a theory known as the theory of cell.
The theory of cell is one of the foundations of modern biology. The main participles in theory of cell are as follows:
a. All living orgasims are composed of one or more cells.
b. Chemical reaction in the cells of living organism occurs inside the cell itself.
c. All new cells are orginated from the existing cells.
d. Each cell contains generic materials inherited from one generation to the next generation.
2.Structure of Cell
Cell is categorized into two types, prokaryote and eukaryote. Prokaryote is the celluler living organism without true nucleus anclosed within membrane.
a. Prokaryotic Cell
prokaryotic cell is very small, 0.00001-0.003 mm. Generally, we study prokaryotic cell through the cells of bacteria and archaebacteria. In bacteria, its cell wall contains a chemical compound called peptidoglycan (glucose chain composition which binds with peptides or short chain of amino acids). Peptidoglycan is not found in the cell of fungi, plants, and other eukaryotic living organisms. The bottom part of the cell walls contains thin, strong, and elastic plasma membranes. Those plasma membranes are composed of two layers of phospholipid molecules (phosphate and lipid compounds) and proteins. The plasma membrane envelopes the cytoplasm. Cytoplasma is colorless fluid; a lot of molecules such as salt, nutrition, end enzymes are dissolved inside it. Cell biochemical process generally occurs in cytoplasma.
The generic materials of cell in teh form of DNA (Deoxyribonucleic Acid) or RNA (Ribonucleic Acid) floet freely in cytoplasma. The size of DNA is about 1.000 times of cell length. Thus, to be fitted in the cells, DNA must be composed in compact structures called chromosomes. The chromosomes in bacteria is circular in shape and located in the part of cells called nucleoid. Besides that, many kinds of bacteria which in their cytoplasma also contained small fish-shaped DNA known as plasmid.
Besides the generic materials, other cell structure contained in bacteria cytoplasma is ribosome. Ribosome functions as the protein manufacture. Ribosome contains RNA (Ribonucleic Acid), a type of generic materials. Besides ribosome, there are no other organellesin the cytoplasm.
b. Eukaryotic Cells
Generally, the characteristics of eukaryotic cell are as folows:
- Have true nucleus to store the generic materials.
- There is mitochondria in animal cells.
- There are chloroplasts and cell walls in the plant cells.
- Eukaryotic cell has inner mambrane which creates compartment in the cell that has a different function.
- Cytoskeleton, which moves the cell cytoplasm, controls the movement of the cells.
Eukaryotic Cell in Plant
