When there are many differences and variations in a species it helps to keep that species healthy.
Meiosis is a process that allows an improved range of genetics because it only contains half of a cell’s genetic material so that the other half can be contributed by another source.
Meiosis is part of sexual reproduction and each parent can give their half to their offspring.
The process of meiosis is very complex, but it narrows down to two main steps:
Here are the details of how our cells accomplish meiosis:
This is the phase involving the reduction of the amount of DNA.
All of us have one copy of our genes that we got from each of our parents. These pairs or sets are chromosome pairs and go by the name of “homologous chromosomes.”
There is a “pairing up” of the homologous chromosomes in prophase I and this is also where they exchange DNA pieces in a “crossover” process.
It’s different in meiosis, as the crossing over creates different chromosome chromatids; not like mitosis, which makes them identical.
Meiosis and mitosis do have actions that are similar in this stage as the chromosomes cluster, there is a disappearance of the nuclear envelope, and there is a formation of the cell “highway” called the mitotic spindle.
Once the crossing over process is complete the pairs will go to the center of the cell and line up in a row.
Those homologous chromosome pairs are each pulled to the opposing cell sides.
This is where the nuclear envelope completely vanishes and if you see the two daughter cells you will note that they now have only half of their previous DNA.
After meiosis I, there is one chromosome in each of the daughter cells, and each of those chromosomes have two sister chromatids that are unique. The goal of meiosis is in the separation of these sister chromatids.
Prophase II happens during the same time period as prophase I, with the exception that there isn’t any crossing over.
This is the lining up in the cell center of the individual chromosomes.
The sister chromatid will pull apart so that each is at the cell’s opposite ends.
From the original cell we have seen the process complete so that it has now formed four unique daughter cells that have 23 chromosomes instead of the original 46.
The only human cells that go through meiosis are the egg and sperm cells. Each parent contributes 23 chromosomes so that the species has a healthy diversity. All other cells in our bodies have 46 chromosomes.
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