Meiosis I

Excellency Top Hat Stay Overnight

Meiosis I Target: I will be able to identify and describe the key stages of Meiosis I. Meiosis: Cell division that results in gametes with half the number of chromosomes as the parent cell. Allows offspring to be genetically different from the parents.   Gametes: Sex cells- Sperm and egg. Pg. 107

Homologous Chromosomes: Identical chromosomes that make up each pair in Meiosis. Meiosis I: Separation of homologous chromosomes.

Diploid: cells that contain two of every chromosome. Haploid: cells that contain one of every chromosome. 1N.

Phases of Meiosis I: 1. Prophase I: Chromosomes are double stranded so they are diploid. The nuclear membrane disappears and spindle fibers form.

Synapsis: homologous chromosomes pair up and attach at their centromeres (called tetrads- groups of 4 chromosomes). Crossing Over: exchange of genetic material between homologous chromosomes.

2. Metaphase I: tetrads line up on the equator.  

3. Anaphase I: The homologous chromosomes pull apart.  

4. Telophase I: cytoplasm divides forming 2 new haploid cells (1N). Half the number of chromosomes than the parent cell, but double stranded.

4. Telophase I: cytoplasm divides forming 2 new haploid cells (1N). Half the number of chromosomes than the parent cell, but double stranded. Summary:

If I were a Gamete… Pretend that you are gamete cell going through Meiosis I Tell me which cell you are (sperm or egg) and then describe what is happening to you at each phase. *Use good grammar. Pg. 106