ap bio mitosis and meiosis

Topics: Chromosome, Mitosis, Cell cycle Pages: 10 (3309 words) Published: February 12, 2014

Mitosis occurs in all eukaryotic cell tissues and produces genetically identical daughter cells with a complete set of chromosomes. In humans, mitosis produces somatic cells that are diploid, which means they contain two non-identical copies of each of the twenty-three chromosomes. One copy is derived from the person's mother and the other from the person's father. Meiosis, on the other hand, occurs only in testis and ovary tissues, producing sperm and ova (eggs). The gametes that are produced by meiosis in humans are haploid, containing only one copy of each of the twenty-three chromosomes. Because of recombination and independent assortment of parental chromosomes, the daughter cells produced by meiosis are not genetically identical. In mitosis, one round of DNA replication occurs per cell division. In meiosis, one round of DNA replication occurs for every two cell divisions. Prophase in mitosis typically takes about thirty minutes in human cells. Prophase in meiosis I can take years to complete. Background information:

In biology, meiosis (pronounced mi-o-sis or me-o-sis) is the process by which one diploid eukaryotic cell divides twice to generate four haploid cells. In animals, meiosis always results in the formation of gametes. The word "meiosis" comes from the Greek meioun, meaning "to make smaller," since it results in a reduction in chromosome number in the gamete cell.

Meiosis is essential for sexual reproduction and therefore occurs in all eukaryotes (including single-celled organisms) that reproduce sexually. A few eukaryotes, notably the Bdelloid rotifers, have lost the ability to carry out meiosis and have acquired the ability to reproduce by parthenogenesis. Meiosis does not occur in archaea or bacteria, which reproduce via asexual processes such as mitosis or binary fission.

Mitosis is the process by which a cell duplicates the chromosomes in its cell nucleus, in order to generate two, identical, daughter nuclei. It is generally followed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles and cell membrane into two daughter cells containing roughly equal shares of these cellular components. Mitosis and cytokinesis together define the mitotic (M) phase of the cell cycle, the division of the mother cell into two daughter cells, each with the genetic equivalent of the parent cell. In simple terms, mitosis is the process where non sex cells reproduce by duplicating DNA and dividing into two identical cells. Each cell has a complete set of chromosomes. These cells are called diploid (double) as they have twice as many chromosomes as the two cells that join via fetilization to form it.

Meiosis is the process where sex cells (called gametes which carry the genetic material for deteriming the sex of an offspring) reproduce by duplicating DNA and diving into four new cells that have half (haploid) the genetic material of the original cell. Both mitosis and meiosis are mechanisms that describe cell division. The difference is particularly noticeable when one looks at the DNA in the cell's nucleus. After mitosis, each of the daughter cells will have exact same DNA strands, while after meiosis each daughter cell will only have half of the DNA strands. (Sometimes the division is not exactly half/half, but that is not important for this answer).

Because meiosis only has half the information that the parent cell had, the cell is (as far as we know) unable to reproduce by itself. The reason for meiosis is for reproduction of a multi-cellular organism as well as genetic diversity due to crossing over. One daughter cell (from the male of the species) will try to find a compatible daughter cell (from the female of the species) and fertilize it. This then becomes and embryo and the specie has successfully reproduced. And this is how you, the reader, came into existence.

Other characteristics:
Parent cell - full set of chromosomes in both...
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