What are the phases of meiosis and what happens in each phase?

Answer 1

Meiosis I:

Prophase I - DNA is exchanged between homologous chromosomes

Metaphase I - chromosomes meet in the centre of the nucleus

Anaphase I - homologous chromosomes are pulled apart

Telophase I - chromosomes arrive at the poles

Cytokinesis - the cell membrane pinches together, and separate cells are formed.

Meiosis II involves the same stages, but ends with 4 daughter cells which contain half the genetic material (known as germ cells).

Answer 2

Meiosis begins with Interphase I. During this phase there is a duplication genetic material, DNA replication. Cells go from being 2N, 2C (N= chromosome content, C = DNA content) to 2N, 4C. Cells remain in this active phase 75% of the time. The chromatin remains in a nuclear envelope while a pair of centrioles lies inside a centrosome.

During Prophase I, the chromatin condenses into chromosomes, the nuclear envelope disappears, and a spindle apparatus begins to form. Each chromosome consists of a pair of chromatids connected by a centromere. Cells are now 4N, 4C. The major occurrence in this phase is the coupling of these homologous chromosomes. Two double-stranded chromosomes form a four-stranded tetrad. In some cases, there is crossing-over of the two middle strands, at a site called the chiasma, such that there is genetic recombination. This process is extremely important for creating genetic diversity.

In Metaphase I, the tetrads line up on the "equator" of the cell. The centrosome has replicated and one has moved to each pole. Microtubules that extend out of each centrosome attach to kinetochores in the center of each side of the tetrads that have lined up on the equator.(29)

Anaphase I occurs as the microtubules pull the pairs of homologous chromatids toward each pole, as the tetrad is divided. The cell begins to lengthen.

During Telophase I, the nuclear envelope begins to reform and nucleoli reappear. The cell begins to split, forming a cleavage furrow in the middle.

In Cytokinesis I, the cells finally split, with one copy of each chromosome in each one. Each of the two resulting cells is now 2N, 2C.

Interkinesis has not replication, unlike the previous Interphase I and the interphase of mitosis.

Prophase II, Metaphase II, Anaphase II, and Telophase II repeats the same steps as Prophase I-Telophase I, with half as much genetic material.

Cytokinesis II is the final step of meiosis, where each cell splits into two daughter cells, for a total of four gametes, each with half the number of chromosomes. Each of the four resulting cells is 1N, 1C. (30)

Answer 3

Meosis occurs basically the same retorical reason mitosis occurs