Question

What are differences between meiosis and mitosis?

Answer 1

Differences Between Mitosis and Meiosis

1. Cell Division

Mitosis: A somatic cell divides once. Cytokinesis (the division of the cytoplasm) occurs at the end of telophase. Meiosis: A reproductive cell divides twice. Cytokinesis happens at the end of telophase I and telophase II.

2. Daughter Cell Number

Mitosis: Two daughter cells are produced. Each cell is diploid containing the same number of chromosomes. Meiosis: Four daughter cells are produced. Each cell is haploid containing one-half the number of chromosomes as the original cell.

3. Genetic Composition

Mitosis: The resulting daughter cells in mitosis are genetic clones (they are genetically identical). No recombination or crossing over occur. Meiosis: The resulting daughter cells contain different combinations of genes. Genetic recombination occurs as a result of the random segregation of homologous chromosomes into different cells and by the process of crossing over (transfer of genes between homologous chromosomes).

4. Length of Prophase

Mitosis: During the first mitotic stage, known as prophase, chromatincondenses into discrete chromosomes, the nuclear envelope breaks down, and spindle fibers form at opposite poles of the cell. A cell spends less time in prophase of mitosis than a cell in prophase I of meiosis. Meiosis: Prophase I consists of five stages and lasts longer than prophase of mitosis. The five stages of meiotic prophase I are leptotene, zygotene, pachytene, diplotene, and diakinesis. These five stages do not occur in mitosis. Genetic recombination and crossing over take place during prophase I.

5. Tetrad Formation

Mitosis: Tetrad formation does not occur. Meiosis: In prophase I, pairs of homologous chromosomes line up closely together forming what is called a tetrad. A tetrad consists of four chromatids(two sets of sister chromatids).

6. Chromosome Alignment in Metaphase

Mitosis: Sister chromatids (duplicated chromosome comprised of two identical chromosomes connected at the centromere region) align at the metaphase plate (a plane that is equally distant from the two cell poles). Meiosis: Tetrads (homologous chromosome pairs) align at the metaphase plate in metaphase I.

7. Chromosome Separation

Mitosis: During anaphase, sister chromatids separate and begin migrating centromere first toward opposite poles of the cell. A separated sister chromatid becomes known as daughter chromosome and is considered a full chromosome. Meiosis: Homologous chromosomes migrate toward opposite poles of the cell during anaphase I. Sister chromatids do not separate in anaphase I.