Question

What are the phases of meiosis? ( full explanation and in order )

Answer 1

The phases of meiosis include meiosis I and meiosis II, each with stages prophase, metaphase, anaphase, and telophase. The main differences from mitosis occur in meiosis I, with homologous chromosomes segregating and genetic variation arising from crossing-over.

Step-by-step explanation:

Meiosis is a two-part cell division process occurring in organisms that sexually reproduce. This process involves two sequential divisions: meiosis I and meiosis II. Both divisions include four stages that are similar to mitotic phases: prophase, metaphase, anaphase, and telophase

Meiosis I starts with a cell that has replicated its DNA during the interphase of the cell cycle and comprises prophase I, metaphase I, anaphase I, and telophase I:

• Prophase I: Homologous chromosomes pair and exchange genetic material in a process called crossing-over, which contributes to genetic diversity.
• Metaphase I: Paired homologous chromosomes line up across the center of the cell.
• Anaphase I: Homologous chromosomes are pulled apart to opposite poles of the cell.
• Telophase I and Cytokinesis: The cell divides into two haploid cells, each with half the number of chromosomes.

The two cells from Meiosis I enter Meiosis II, which is similar to mitotic division and includes prophase II, metaphase II, anaphase II, and telophase II:

• Prophase II: Chromosomes condense and the spindle fibers form.
• Metaphase II: Chromosomes align at the cell's equator.
• Anaphase II: Sister chromatids are finally separated and pulled to opposite poles of the cell.
• Telophase II and Cytokinesis: Cells divide again, resulting in four unique haploid cells, each with an individual set of chromosomes.

Meiosis differs from mitosis mainly in Meiosis I, where homologous chromosomes segregate, which does not happen in mitosis. Moreover, crossing-over in prophase I adds to the genetic variation of the resultant gametes.

Answer 2

Interphase: -the cell replicates its chromosomes -each chromosome has two sister chromatids held together by a centromere Prophase 1 chromosomes coil up and a spindle forms -homologous chromosomes come together matched gene by gene forming a tetrad -Crossing Over may occur when chromatids exchange genetic material -this occurs two or three times per pair of homologous chromosomes -Crossing Over results in new combinations of alleles on a chromosomes Metaphase 1: -the centromere of each chromosome becomes attached to a spindle fiber -the spindle fibers pull the tetrads to the equator of the spindle -homologous chromosomes are lined up side by side as tetrads Anaphase 1: -homologous chromosomes separate and move to opposite ends of the cell -centromeres do not split -this ensures that each new cell will receive only one chromosome from each homologous pair Telophase 1: -the spindle breaks down and the chromosomes uncoil -the cytoplasm divides to yield two new cells -each cell has half the genetic information of the original cell because it has only one homologous chromosome from each pair Prophase II- -a spindle forms in each of the two new cells and the fibers attach to the chromosomes Metaphase II- -the chromosomes are pulled to the center of the cell and line up randomly at the equator Anaphase II- -the centromere of each chromosome splits the sister chromatids separate and move to opposite poles Telophase II nuclei re form the spindles break down the cytoplasm divides identical to mitosis (Meiosis II) What Meiosis produces four haploid sex cells from one original diploid cell each haploid cell contains one chromosome from each homologous pair haploid cells will become gametes transmitting genes to offspring

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