Question

Explain the following

A. Division of labour is seen in cell organelles

B. Mitochondria are semi-autonomous bodies.

Answer 1

Hint: All organisms are composed of compartment-like structures called cells. Some are composed of single cells and are called unicellular organisms and others are composed of multiple cells and are called multicellular organisms. Independent existence is exhibited by the unicellular organisms. They can perform the essential functions of life in a single cell only.

Complete answer:

(A). Anything less than a complete structure of a cell does not ensure independent living. Hence cells are the fundamental and structural unit of all living organisms. Every cell contains a semi-fluid matrix called cytoplasm. It occupies the maximum volume of the cell. The cytoplasm is the main arena of all cellular activities in both plants and animal cells. 

The eukaryotic cells have other membrane-bound distinct structures called organelles like endoplasmic reticulum, the golgi complex, lysosomes, mitochondria, and microbodies. The prokaryotic cells lack such membrane bound organelles. All the organelles perform specific functions. Thus a complete division of labour is seen in cell organelles. 

(B). Mitochondria is one of the major organelles of the eukaryotic cell. It is responsible for energy production in a cell. It is a double membrane bound organelle that produces ATP and thus regarded as the powerhouse of the cell.

New mitochondria arise from the division of pre-existing mitochondria. Mitochondria is divided by the binary fission. The origin of mitochondria is endosymbiotic (prokaryotic origin). Since it has its own genetic material and ribosomes for protein synthesis but still requires some protein of nuclear origin. Thus the mitochondria is known as a semi autonomous body.

Note: There is another semi-autonomous body present inside the plant cell and it is called a chloroplast. Chloroplasts are responsible for the photosynthesis in the plant.

The DNA of the chloroplasts is also similar to the DNA of prokaryotes. Also, the ribosomes are similar to that of prokaryotes. The biogenesis of chloroplasts occurs from pro plastid. These are also formed by the binary fission of pre-existing plastids (endosymbiotic origin).