What is Meiosis? What Does it Produce?
Meiosis is the process that forms gametes, or sex cells. Sex cells are what combine during fertilization to produce offspring. Meiosis occurs in the ovaries/testes. In humans, gametes are eggs and sperm.
All of the cells in our body are diploid (2n). This means that each chromosome has a homologous pair. We have 46 chromosomes in our cells, and they all pair up, making 23 homologous pairs. Gametes are the exception to this - they are haploid (n). This means that there is only one of each chromosome, no homologous pairs. There are only 23 chromosomes in our haploid cells - in our gametes - in an egg or sperm. When two haploid (n) cells come together during fertilization (egg+sperm), a zygote is produced (a fertilized egg is called a zygote). Two cells, each with 23 chromosomes (one of each) come together causing their DNA to be in one nucleus. As the chromosomes are in the same place, they can now pair up. So once a sperm (n) and an egg (n) become one, you end up with a diploid (2n) cell which is the offspring. Gametes are not identical. There are 23 homologous pairs of chromosomes and either chromosome from each pair can end up in the gamete - this means there are so many different possible combinations of chromosomes that could end up in the sperm/egg. This is important to know. |