Meiosis


 * Meiosis

Meiosis is a special from of cell division that produces gametes that are then used in sexual reproduction. Meiosis allows the daughter cells have one half of the parent cell. The purpose of producing gametes with different genes is for genetic variability within a species. The gametes must have one half the chromosome number because when the gametes unite to form a zygote, they will have the correct number of chromosomes.



[|Meiosis VS. Mitosis] and in depth comparison between meiosis and mitosis

Questions for Review:

1. What is the chromosome number of the first cell in this diagram? 2. What is the chromosome number of the last cell in this diagram? 3. What stage in meiosis does synapsis occur? 4. What is the main difference between meiosis and mitosis? 5. Where is a tetrad? 6. Where are homologous chromosomes? 7. How many pairs of homologous chromosomes do humans have?

Answers: 1. Meiosis begins with diploid cells (2N). 2. Meiosis ends with haploid (N) cells 3. Synapsis occurs in Prophase I. 4. Mitosis results in the production of two genetically identical diploid cells, whereas meiosis produces four genetically different haploid cells. 5. The tetrad is found in Prophase of one of meiosis after the duplicated chromosomes have paired up. This is in the third picture of the diagram. 6. Homologous chromosomes are found in the third picture of the diagram. 7. Humans have 23 pairs of homologous chromosomes.

More information on meiosis can be found from 275-278 in our text book.**