I do wish that meiosis was named something different, because students seem to get it confused with mitosis. The two processes are related in some ways, but the end product of meiosis is very different from that of mitosis. Mitosis will produce cells that have the full, diploid chromosome count.
Let's use a human cell for an example. Human cells contain 46 chromosomes. When a cell undergoes mitosis, each of the new daughter cells contains 46 chromosomes. Meiosis, on the other hand, won't produce cells with 46 chromosomes. Meiosis will produce cells that contain exactly half the diploid chromosome count. In the case of humans, meiosis produces four cells that each have 23 chromosomes. This is why meiosis is sometimes referred to as "reduction division."
The reduced chromosome count is critical for sexual reproduction, because sexual reproduction requires genetic information to come from two sources. Again, I'll use humans as an example. The resulting cell from meiosis is called a gamete. In females, the gamete is an ovum (egg), and in males it is a sperm cell. The sperm and the egg each contain 23 chromosomes. That's half the normal human number, so gametes are haploid cells. The sperm cell will join the egg cell for fertilization, and the chromosomes from the two gametes will be combined. The two haploid cells will have made a diploid cell, with 46 chromosomes. This is why sexual reproduction produces new genetic information. DNA is coming from two sources and gets shuffled around during meiosis, combining in new ways during fertilization.
https://www.mun.ca/biology/desmid/brian/BIOL2060/BIOL2060-20/CB20.html
Wednesday, January 23, 2013
Describe the role of meiosis in producing sex cells for sexual reproduction
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