Cell Principle

Topic :-3,from Cell, the unit of life.

• The modern cell Theory is called cell Principle.

It includes following parts___:-

1. cell is the basic structural and functional unit of life.
2. cell is the smallest unit in which life can exist.
3. All living beings are composed of cell.
4. Each cell comsistd of protoplasmic mass containing a nucleus.
5. A cell is able to maintain its vitality and individuality.
6. cell always arise from prexisting cells.
7. All present day cell have a common origin.
8. No organism can have activity without cells.

Bascially cell are Totipotent unless and until they are specialised.

CELL THEORY IS A GENERALISATION.

1. It is having many exceptions.
2. Viruses donot show cell structure but they show some living properties.
3. In some organisms body is not diffrentiated into cells;and it consist of a chamber of nuclei as in Mucor and Rhizopus fungi.
4. Protozoa shows subcellular diffrentiation for different work.
5. There are many cell which donot have true nucleus (Prokaryotes).
6. Mammalian Rbc's & sieve tube cell are living cells,which are without nuclei.
7. Highly evolved organisms can show even those activities which are not found in their cells.eg...Man can speak but the constituents cells cannot.
8. Rbc living cell without nucleus.

Biggest exception of cell theory - Viruses.

Feature common to all cells:------

1. Havin genetic material.
2. Having cell membrane.
3. Having protoplasm.
4. Having same genetic code.
5. same method of DNA replication.
6. Having same genetic continuity.
7. Cellular Totipotency.it is the ability of somatic cell to form the whole organisms.(Micropropagation)

Cellular Totipotency:-

1. It is the ability of somatic cell to form the Organism.
2. Totipotency can be easily demonstrated in plant cell.
3. It was first started by German Botanist Haberlandt In 1902.
4. Later Experiment demonstrated by Steward.

Uses of cellular Totipotency:------

1. In tissue culture , it is the basis of this process.
2. Micropropagation.
3. production of virus free plant.
4. Artificial seed production .
5. Cloning.
6. Cultivation of rare plant by tissue culture.