Stages of Meiosis - Assignment Example

of the of the of the PHASES IN MEIOSIS Meiosis is the type of cell division that takes place in organisms that reproduce sexually. Commonly it is often referred to as two part cell division. The reproduced gamete contains half the amount of chromosomes that the parent cell contains. The entire process eventually results in the production of four daughter cells each of which contains half the number of chromosomes as the parent cell. It can be divided into MEIOSIS I and MEIOSIS II. Following are the list of phases through which a cell undergoes during the process of meiosis.

MEIOSIS IINTERPHASEBefore the process of meiosis begins the chromosomes prepare themselves for the process. The cell increases in mass. The chromatids of each chromosome (two sister chromatids of one chromosome) are held together by a centriole.PROPHASE IChromosomes coil up together forming a spindle. Homologous chromosomes come closer and form a tetrad. For each pair of homologous chromosomes the exchange of genetic material may result in the crossing over of chromosomes. New combinations of alleles on chromosomes are the result of crossing over.

Figure 1: MEIOSIS IMETAPHASE IThe centromere of each chromosome attaches itself with a spindle fiber.The metaphase plate (as shown in the figure) is at the equator of the spindle fibers. It is here that the homologous chromosomes line themselves up as tetrads. ANAPHASE IThe homologous chromosomes disperse and move towards opposite poles of the cell. The resultant is the assurance that each new cell that will eventually form would receive only one chromosome from homologous pair. TELOPHASE IThe spindle breaks down and the chromosomes uncoil eventually dividing the cytoplasm into two separate portions.

Two daughter cells form. They contain exactly half of genetic information of parent cell. This is because they contain only one homologous chromosome. MEIOSIS IIThe following figure an overall view of the second phase of meiosis or meiosis II. The narration of the respected phases is presented after the illustration. Meiosis II is similar to Mitosis.Figure 2: MEIOSIS II PROPHASE IISpindle fibers form in each of the two cells. Chromosomes line themselves up with the spindle. METAPHASE IIThe chromosomes line themselves up at center of the spindly fibers or the metaphase plate.

ANAPHASE IIEach chromosome splits at its centromere. The separated chromatids get pulled to opposite poles of the spindle fibers. TELOPHASE IIThe spindles break down and diminish. The cytoplasm divides after the nuclei have formed again.CYTOKINESISEntire cell breaks up into two complete daughter cells. Each new cell is a copy of its parent cell and is referred to as a haploid daughter cell.WORKS CITED:Campbell, Neil A, and Jane B. Reece. Biology. San Francisco: Pearson Benjamin Cummings, 2009.

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