Why is meiosis also called as 'reduction division' ?

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trophyhunter1 eNotes educator| Certified Educator

Meiosis is a reduction division because the end result of this special type of cell division is four haploid cells. These can be used as gametes--sperm or egg cells in sexually reproducing organisms. In order to preserve the species number of chromosomes, the gametes must have half the chromosomes as a diploid body cell has. At fertilization, when two haploid cells unite, they form a diploid zygote with the correct number of chromosomes for that species. For instance, meiosis produces sperm and egg cells in humans with 23 chromosomes in each. At fertilization, a zygote with 46 chromosomes is the result. Forty six is the species number of chromosomes for Homo sapiens. Meiosis occurs in the gonads--ovaries and testes. A human gonad cell with 46 chromosomes undergoes replication resulting in 46 pairs or 92 chromosomes. The first meiotic division occurs which results in two cells, each with 46 chromosomes. Then, the second round of meiotic division occurs and each of these two cells divides resulting in four haploid cells. In males, these become four sperm cells and in females, these become one egg(ovum) which is the gamete and 3 polar bodies that are not used to produce the zygote.

sanjeetmanna eNotes educator| Certified Educator

The cells produced by meiosis are gametes or spores, this type of cell division is necessary for sexual reproduction to produce gametes.

Meiosis start with diploid cell and following the outcome of meiosis(Meiosis I and Meiosis II) produce 4 cells which is haploid in nature.

Parent cell =  46 chromosomes (Diploid)

Meiosis I = 2 cells (out come) = 46 * 2 = 92 chromosomes.

Meiosis II = 4 cells ( out come ) = 92/4 = 23 chromosomes(Haploid)

The haploid cells will have 23 chromosomes that is half the parent chromosomes, since we can see the reduction in number of chromosomes it is called as reduction division.

Diploid = 46 chromosomes.

Haploid = 23 chromosomes.