Both the male and female gametesreproduce by a cell division process known as meiosis. This process is made up of two distinct phases, known as meiosis I and meiosis II.
During meiosis I , chromosomes replicate, leading to two full sets of chromosomes, during what is known...
Both the male and female gametes reproduce by a cell division process known as meiosis. This process is made up of two distinct phases, known as meiosis I and meiosis II.
During meiosis I, chromosomes replicate, leading to two full sets of chromosomes, during what is known as Interphase. At the end of interphase, the gamete cell has 2 of each chromosome, with 4 total chromatids per pair.
Following interphase, prophase I occurs. In this phase, chromosomes pair up together, so that the same chromosome is with its partner, (ex. chromosome 10 pairs with chromosome 10 and chromosome 11 pairs with chromosome 11 etc.) During this process, each pair of chromosomes can randomly exchange small bits of DNA, leading to what is generally known as crossing over, or recombination. This process leads to increased genetic diversity of the offspring. Towards the end of prophase I, the nuclear envelope is dissolved, and meiotic spindle fibers, composed mostly of microtubules, attach to the chromosomes.
The next step of the process, metaphase I, then occurs. During this step, the chromosomes line up at the center of the cell.
Following this alignment, anaphase I occurs, and each pair of chromosomes splits up, with one set of chromosomes migrating towards one end of the cell, and the other set migrating towards the opposite end.
Once the chromosomes reach opposite ends of the cell, the final phase Telophase I, followed by cytokinesis, occurs. At this stage, a full set of chromosomes, now at each end of the cell, come together, and a new nucleus is formed around each set. The gamete cell then pinches off at the middle, forming two new daughter cells, each with a full set of 23 chromosomes and 46 total chromatids.
A similar process is repeated in what is known as meiosis II, where the two cells from meiosis I, each containing 23 chromosomes and 46 chromatids, produce a total of four gamete cells, each with 23 chromatids, used for sexual reproduction. Hope this helps!