Contact a health care provider if you have questions about your health. How do cells divide? From Genetics Home Reference. Mitosis and meiosis, the two types of cell division. Topics in the How Genes Work chapter What are proteins and what do they do?
How do genes direct the production of proteins? In meiosis 2, which is quite similar to mitosis, the two diploid cells further divide into four haploid cells. Share this comparison:. If you read this far, you should follow us:. Diffen LLC, n. All organisms. No, crossing over cannot occur.
Definition A type of cellular reproduction in which the number of chromosomes are reduced by half through the separation of homologous chromosomes, producing two haploid cells. A process of asexual reproduction in which the cell divides in two producing a replica, with an equal number of chromosomes in each resulting diploid cell. Cellular reproduction and general growth and repair of the body.
Remains the same. Prophase, Metaphase, Anaphase, Telophase. Karyokinesis Occurs in Interphase I. Occurs in Interphase. Occurs in Telophase.
The centromeres split during anaphase. A membrane forms around each set of chromosomes to create two new nuclei. The single cell then pinches in the middle to form two separate daughter cells each containing a full set of chromosomes within a nucleus. This process is known as cytokinesis. Meiosis II 6. Prophase II: Now there are two daughter cells, each with 23 chromosomes 23 pairs of chromatids.
In each of the two daughter cells the chromosomes condense again into visible X-shaped structures that can be easily seen under a microscope.
The membrane around the nucleus in each daughter cell dissolves away releasing the chromosomes. The centrioles duplicate. The meiotic spindle forms again. Metaphase II: In each of the two daughter cells the chromosomes pair of sister chromatids line up end-to-end along the equator of the cell. The centrioles are now at opposites poles in each of the daughter cells.
Meiotic spindle fibres at each pole of the cell attach to each of the sister chromatids. Anaphase II: The sister chromatids are then pulled to opposite poles due to the action of the meiotic spindle. The separated chromatids are now individual chromosomes. Telophase II and cytokinesis: The chromosomes complete their move to the opposite poles of the cell. A membrane forms around each set of chromosomes to create two new cell nuclei. This is the last phase of meiosis, however cell division is not complete without another round of cytokinesis.
Once cytokinesis is complete there are four granddaughter cells, each with half a set of chromosomes haploid : in males, these four cells are all sperm cells in females, one of the cells is an egg cell while the other three are polar bodies small cells that do not develop into eggs. Between prophase I and metaphase I, the pairs of homologous chromosome form tetrads. Within the tetrad, any pair of chromatid arms can overlap and fuse in a process called crossing-over or recombination.
Recombination is a process that breaks, recombines and rejoins sections of DNA to produce new combinations of genes. In metaphase I, the homologous pairs of chromosomes align on either side of the equatorial plate. Then, in anaphase I, the spindle fibers contract and pull the homologous pairs, each with two chromatids, away from each other and toward each pole of the cell. During telophase I, the chromosomes are enclosed in nuclei. The cell now undergoes a process called cytokinesis that divides the cytoplasm of the original cell into two daughter cells.
Each daughter cell is haploid and has only one set of chromosomes, or half the total number of chromosomes of the original cell. Meiosis II is a mitotic division of each of the haploid cells produced in meiosis I. During prophase II, the chromosomes condense, and a new set of spindle fibers forms.
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