University:
High School
Course:
High School Biology
Academic year:

2019
Views:

180

Pages:

9
Author:

Giselle A.

Meiosis Chapter 8 Section 3 Making Gametes **Meiosis – division of 1 diploid nuclei into 4 haploid nuclei. • ****Sex cells – only type of cell in your body that undergoes meiosis – Found in gonads (ovaries or testes • Haploid (1n) – cells with only 1 of each chromosome. • Gamete – egg or sperm. • ***Purpose - Only sex cells undergo meiosis to produce gametes. Meiosis I • • • • • Same phases as Mitosis S Phase of interphase copies chromosomes Cells begin process with two of each chromosome T-chart Prophase I **Differences from prophase in mitosis: 1. Homologous chromosomes pair with each other 2. Corresponding genes are next to each other • important Metaphase I • Homologous chromosomes line up randomly • Meet in Middle – Homologous chromosomes are next to each other • **Double file….Not single file** Anaphase I • Homologous chromosomes randomly move to opposite poles Telophase I • Cells are now haploid, – Nuclear membranes reform • BUT each nucleus contains two copies of each chromosome Meiosis II • DNA is not copied first – skips S phase • The 2 new cells begin Prophase II – Nuclear membrane dissolves – Chromosomes begin to move toward middle • Metaphase II – Chromosomes line up in middle single file Anaphase II • Chromatids separate • Move to opposite poles Telophase II • Nuclear membranes form • Cytokinesis occurs in each cell • 4 new cells are created – gametes Meiosis in humans Purpose Create 4 haploid cells called gametes Type of cells in which it occurs Sex cells Chromosome # at beginning Chromosome # at end Number of Cells at beginning 46 Number of Cells at end 4 23 1