chapter  2
10 Pages

Chromosomes and Cell Division

WithArchana Sharma, Sumithra Sen

The behavior of chromosomes follows a distinct pattern in the body, termed mitosis, quite different from that in germ line, the meiosis. Meiosis entails two divisions of the nucleus, one of which is equational and the other is reductional. It characteristically results in the separation of homologous chromosomes and halving of the chromosome number. In mitosis, chromosomes undergo longitudinal division, each half going to one daughter cell. Following reconstitution at the end, the same number is maintained throughout the somatic cells. Chromosomes arrange themselves at the equator, being attached to the spindle at the centromeric region. The synaptonemal complex (SC) is considered as the ultrastructural manifestation of meiotic chromosome pairing and synapsis. The SC as such is a tripartite body located between the synapsed chromosomes. Substantial regions of chromosomes that constitute heterochromatin remain condensed throughout the division cycle, including interphase.