Question

What are life process of amoeba explain.

Answer 1

Life cycle of Amoeba Reproduction in amoeba is a periodic process taking place at intervals. Reproduction in amoeba chiefly occurs by asexual method, i.e., by binary fission, multiple fission and sporulation.
(i) Binary fission: It is the most common mode of reproduction. In this process, the whole body divides into two daughter amoebae by mitosis. The division involves nuclear division (karyokinesis) followed by division of cytoplasm (cytokinesis). This takes place during favourable conditions.
(ii) Sporulation: Under un-favourable conditions amoeba reproduces by formation of spores internally. It starts with the breakdown of nuclear membrane and release of chromatin blocks into the cytoplasm. Each chromatin blocks acquires a nuclear membrane and becomes a small daughter nuclei. The newly formed nuclei get surrounded by cytoplasm to form amoebulae. The peripheral cytoplasmic layer of amoebulae forms a tough and resistant spore-membrane or spore case . About 200 such spores are formed inside a single parent amoeba. Finally the body of parent amoeba disintegrates to release the spores. The spore remain inactive for some time and on getting favourable conditions each spore forms a young amoeba.
(iii) Multiple fission: In un-favourable conditions, amoeba divides by multiple fission. It withdraws its pseudopodia, becomes spherical and secretes three layered cyst around itself. Its nucleus undergoes repeated mitosis division forming 500- 600 daughter nuclei. Each daughter nuclei gets surrounded by mass of cytoplasm and divides into minute amoebulae. On getting favourable conditions the cyst ruptures to release the amoebulae which soon grows into adult amoeba .Regeneration: Amoeba has tremendous power of regeneration. If it is cut into small pieces, each piece regenerates into a new amoeba, however, a piece without nuclear fragment does not regenerate.