The stages of mitosis are prophase, where the membrane around the nucleus disappears, and the DNA in the chromosomes and their copies become more visible within the cell. During the metaphase, the chromosomes and their copies line up in the middle of the cell. In the anaphase stage, the chromosomes are pulled to the ends of the cell, whereas in the telophase stage form, new membranes around the chromosomes at each end of the cell. (Fowler et al., 2021).

 

Fowler, S., Roush, R. & Wise, J. (2021, January 12). Concepts of biology.Open Stax College

Meiosis I

The interphase consists of two centrosomes containing a pair of centrioles outside the nucleus. The DNA within the cell is copied, making two identical sets of chromosomes.             Prophase I is where copied chromosomes condense into x-shaped structures and are composed of two sister chromatids containing exact genetic information. The chromosomes pair up to exchange pieces of DNA. This process is called recombination or crossing over. The meiotic spindle consists of microtubules and other proteins and extends across the cell between the centrioles, and the membrane around the nucleus dissolves, releasing the chromosomes.                                                                                             In Metaphase I, the chromosome pairs are lined up at the center of the cell, and the centrioles are at opposite ends with the meiotic spindles extended. The meiotic spindle fibers attach to one of the chromosomes of each pair.             During anaphase I, the chromosome pairs are pulled apart by the meiotic spindle, which pulls the separated chromosomes to the opposite ends of the cell. The final phase of stage one is telophase I and cytokinesis. A membrane will form around each set of chromosomes to create two new nuclei. The single cell then pinches to form two separate daughter cells containing a complete set of chromosomes in a nucleus. (yourgenome.org, 2023).

Meiosis II

In prophase II, the two daughter cells containing the twenty-three chromosomes condense for a second time into visible x-shaped structures. The membrane around the nucleus again dissolves, releasing the chromosomes, and the centrioles duplicate as again the meiotic spindle reforms. Metaphase I is replicated in metaphase II, with the daughter cells lining up in the center of the cell and the centrioles at the opposite ends. The meiotic spindle fibers attach to each of the chromatids.                               
Anaphase II is when the meiotic spindle pulls the chromatids to the opposite ends and are now individual chromosomes.     The final is telophase II and cytokinesis, where the chromosomes finish their move to the opposite ends of the cell, and a membrane forms around each new set to create two new cell nuclei. Cytokinesis completes the process. At this stage, four grandaughter cells each have a half batch of chromosomes. In males, these four cells are sperm cells; in females, one cell is an egg cell, and the other cells are polar bodies that do not develop into eggs. (yourgenome.org, 2023).

Mendel's law of independent assortment states that the allele a gamete receives does not influence the allele obtained for another gene. During meiosis, chromosomes generate a variation by crossing over at points called chaisma. At the chiasma points, the chromosomes break and rejoin to trade some of their genes. The recombination results in genetic variation. (Fowler et al., 2021).

 

Fowler, S., Roush, R. & Wise, J. (2021, January 12). Concepts of biology.Open Stax College