Compare the processes of mitosis and meiosis, including differences between sexual and asexual reproduction.
Mitosis is a type of cell division that occurs in a diploid cell. It produces two identical copies of the parent cell, called daughter cells. If a cell in a human has 46 chromosomes, after mitosis, two cells each with 46 chromosomes will be produced. That is because during interphase, the chromosomes in the cell are replicated or copied. Then, after the cell goes through prophase, metaphase, anaphase and telophase and finally cytokinesis, two daughter cells will each have the full set of chromosomes as the parent cell does, but only half the cytoplasm. Mitosis in humans is a way for growth and repair to occur within the body. Mitosis can be a type of asexual reproduction, when a one-celled organism like an ameba, yeast or algae divide and form two cells from one parent cell. Meiosis is a reduction- division. It occurs in the gonads of sexually reproducing organisms--testes and ovaries. A body cell in the gonad which is diploid will eventually form 4 haploid cells as a result of meiosis. In a human, an ovary or teste cell has 46 chromosomes. Replication of the DNA occurs and meiosis I proceeds. Prophase I is where crossing over occurs and homologous chromosomes in groups of four called tetrads exchange pieces of DNA. This results in variability in the gametes later on. Metaphase I, Anaphase I and Telophase I occur and then, meiosis II begins. By having the second round of cell division, four haploid cells result, in this case, each has 23 chromosomes or half the amount as in body cells. Males produce 4 haploid sperm cells, while females produce a larger haploid egg cell and 3 polar nuclei that are not used as gametes. These gametes which are haploid will join together at fertilization in sexually reproducing organisms, to produce a diploid zygote.