Thursday, 6 September 2012

Why Meiosis 1st is known as reductional division?


Meiosis I separates homologous chromosomes, producing two haploid cells (N chromosomes, 23 in humans), so meiosis I is referred to as a reductional division. A regular diploid human cell contains 46 chromosomes and is considered 2N because it contains 23 pairs of homologous chromosomes. However, after meiosis I, although the cell contains 46 chromatids, it is only considered as being N, with 23 chromosomes. This is because later, in Anaphase I, the sister chromatids will remain together as the spindle fibers pull the pair toward the pole of the new cell. In meiosis II, an equational division similar to mitosis will occur whereby the sister chromatids are finally split, creating a total of 4 haploid cells (23 chromosomes, N) - two from each daughter cell from the first division

0 comments:

Post a Comment

Powered by Blogger.