Read this article to learn about Cell as a Self-Contained (Autonomous) Unit !
Each cell, whether of unicellular or multicellular organisms, acts as an autonomous unit i.e. able to carry out activities independent for its own survivalist.
This can be justified from following facts.
1. Each cell obtains food, oxidize them to produce energy and store this energy in the form of ATP.
2. Each cell can respire and exchange gases with its surrounding.
3. Each cell synthesize the own macromolecules from macromolecules.
4. With the help of its lysosomes, each cell discards it’s worn out components.
5. Metabolic wastes are discarded by each through its own mechanism.
6. Each cell may undergo division, producing identical daughter cells.
7. Each cell can maintain homeostasis.
8. Cells regulate their activity through (i) flow of energy and (ii) flow of information.
9. The whole genetic information is contained in a cell and can be made to grow into a fully develop and organism (a phenomenon called totipotency).
10. Each cell has its own life span. A cell may grow, divide and die while its surrounding cells may be in a different state.
Cellular Autonomy in Unicellular Organism:
A cell of a unicellular (single celled) organism has absolute independent existence. It does not depend upon any other cell for any function, material or information. Except for sexual reproduction, all activities are carried out by the same cell.
The division of labour at the cellular level is here. However, it does exist at sub-cellular level.
Cellular Autonomy in a Multicellular Organism:
Situation regarding cellular autonomy is slightly different in multi-cellular organism s where all the cells are not in direct contact with external environment. Such cells coordinate with other cells for different functions and thus show division of labour. They also become specialize for additional functions, such as secretion, support, protection etc.
Due to specialization, the cells of multi-cellular organism may lose certain activities necessary for autonomy; for example, erythrocytes do not respire. Mature nerve cells cannot undergo division nevertheless, these cells still retain the capacity for independent existence. They only depend on other cells for their additional activities for the survival of the organism in which they are present.