how is meiosis called reducttional division...??? i cannot understand from video...plz...plz explain...its urgent...
Meiosis is known as the reductional division beacuse it results in the reduction of the chromosome number to half. This type of cell division mainly occurs in the gametes (gametic meiosis). In some plants, it also takes place in the zygote (zygotic meiosis). As far as your doubt is concerned, the first phase of the meiosis (i.e. meiosis I) results in the reduction of chromosome number, thus it is called the reductional deivision. If you have difficulty in understanding, consider a diploid parent cell (2N) with only two chromosomes in a cell. During meiosis phase I, which is referred to the reductional phase, the two chromosomes will move apart and each cell will receive only one chromosome. The daughter cell produced will have single set of chromosomes (1 N) but parent had two chromosomes (2 N), So at the end of meiosis I , each daughter cell contains only half a chromosome. Since the total number has been reduced by half, it is called reductional division.
Normally during cell cycle, mitosis takes place where the no. of chromosomes remains constant in both the parent as well as the progeny cell (i.e. 2n).
But Meiosis is a reductional division as the no. of chromosomes(2n) becomes half instead of remaining constant during cell division (i.e. it becomes n). It occurs during the formation of male gametes (sperms) and female gametes (eggs) in animals. In plants it occurs when spores are produced.