Meiosis

Meiosis is the process of one diploid cell dividing into four haploid cells or gametes, and it's essential for reproduction. There two parts to meiosis and each part is spilt into several different phases.

• Part one:
• Interphase I
• During interphase the cell begins to grow so that it has enough room to divide (G1 phase), then it copies its DNA (S phase), then it continues to grow (G2 phase).
• Prophase I
• The DNA in the cell begins to move towards the middle while also pairing up with a homologue partner so they become a homologues pair. Crossing over also happens in this phase.
• Metaphase I
• The DNA has lined up in the center and the centrioles are attached, just like mitosis
• Anaphase I
• Now the homologous pairs have been separated and pulled to opposite ends of the cell.
• Telophase I
• The nucleus is reforming and the cell starts to separate into two daughter cells.
• Cytokinesis I
• The cells have separated and start meiosis II.

Part one is mostly the same except for a few things here and there, but other than that it's the same. Part 2 on the other hand has no Interphase because the diploid daughter cells do not replicate DNA. This is because sex cells are haploid cells meaning they have half of what normal cells have.

• Part two:
• Prophase II
• Nuclear envelope breaks down if needed and centrioles move to opposite poles again
• Metaphase II
• Same as metaphase I however the chromosomes line up individually along the metaphase plate.
• Anaphase II
• The sister chromatids are pulled apart to opposite sides of the cell.
• Telaphase II
• The nuclear membrane reforms and the two daughter cells begin to separate into four gametes.
• Cytokinesis II
• The results are four gametes, whether they be four egg or four sperm cells.
• After cytokinesis II the sex cell cannot divide anymore, so you have to start all over with new cells.

I think that this could be useful information for someone who wanted to learn how sperm and egg cells are created or a med school student who needs the information for a research paper. I didn't really learn anything about meiosis, only because I've gone over it in previous science classes so this was just review.

Citations:

Info: "Meiosis." Khan Acadamy, www.khanacademy.org/science/biology/cellular-molecular-biology/meiosis/a/phases-of-meiosis. Accessed 4 Jan. 2017.

Picture: Kuensting, Steve. "Meiosis." 2005, www2.sluh.org/bioweb/bi100/tutorials/meiosis.htm.