In the past, we learned about reproduction from a giant view. We were taught to understand the functions of reproductive organs, and we were aware that sexual reproduction occurs when a sperm meets an egg. This year, our class looked at reproduction again but explored this subject from a more microscopic view. We focused on the two methods of cellular reproduction: mitosis and meiosis.
Mitosis occurs in body cell reproduction for eukaryotic cells, while prokaryotic cells can simply go through binary fission to make an identical copy of itself. As a cell goes through the interphase, prophase, metaphase, anaphase, telophase, and cytokinesis, it results into two identical cells with the same number of chromosomes and the same set of genes. Below are the procedures to mitosis:
Interphase: The interphase is the first stage of the eukaryotic cell cycle. In interphase G1, the cell grows bigger to prepare itself. In interphase S, the chromosomes in the cell duplicate itself so that the two cells end up to have the same number of chromosomes.
Prophase: The prophase is when mitosis begins. It is also the phase of a cell cycle where chromosomes become visible as they condense into rodlike structures.
Metaphase: The nuclear membrane dissolves and paired chromatids line up at the equator of the cell.
Anaphase: The sister chromatids separate to move to opposite sides of the cell as microtubules that come out from the centrioles attach onto the centromeres of the chromosomes.
Telophase: The microtubules pull the sister chromatids apart as a nuclear membrane forms around each set of chromosomes.
Cytokinesis: The cell pinches itself into two for the cells without cell walls. If the cell contains a cell wall, a cell plate forms between the two new cells.
In meiosis, the cell duplicates itself one time but divides itself two times. Meiosis occurs to produce sex cells. Sex cells (eggs or sperms) have half the number of chromosomes in body cells, which means they are haploid cells. For example, humans have 46 chromosomes in their body cells, but in their sex cells, there are only 23 unpaired chromosomes because two sex cells will eventually join together to create a zygote that has 46 paired chromosomes.
We learned these complicated methods of cellular reproduction by doing worksheets from the textbook and watching videos about this subject. I also found looking at the onion cell images interesting, but it would definitely make a better learning experience if we can examine onion cells through a real microscope. In the future, I hope we can have more class discussions and actual teaching instead of learning on our own.
Both mitosis and meiosis play an important role in cellular reproduction. Meiosis helps to create a new individual with genetic variability so that the organism has a higher chance to adapt to the changing environment. On the other hand, mitosis creates clones of the original cell to help an individual grow and develop. I think learning about mitosis and meiosis is fascinating since they are essential factors of keeping us alive and making each of us different.
