Defined Gametes from two separate parents unite Meiosis Diploid 2n to haploid n cells Mechanism that allows for genetic diversity Many eukaryotes reproduce in this manner Plants animals and fungi ID: 1043280
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1. Meiosis Overview
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4. Sexual Reproduction Defined: Gametes from two separate parents uniteMeiosis: Diploid (2n) to haploid (n) cells Mechanism that allows for genetic diversityMany eukaryotes reproduce in this mannerPlants, animals and fungi
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6. Meiosis: Prophase I Prophase I- chromosomes become visible and nuclear membrane breaks down. Crossing over occursportions of one sister chromatid are broken and exchanged with portions of the corresponding chromatid of homologous chromosome.
7. Meiosis: Metaphase IHomologous chromosomes move to the middle of the cell and stay together.
8. Meiosis: Anaphase IThe homologous chromosomes are pulled apart to opposite sides of the cell via spindle fibers. Notice that the sister chromatids are still linked together at the centromere.
9. Meiosis: Telophase I/ CytokinesisA nuclear membrane reforms around the separated chromosomes Two new __________ diploid cells are formed
10. Meiosis II: Prophase IIThe nuclear membrane dissolves around the chromosomes
11. Meiosis II: Metaphase IIChromosomes line up in the middle of the cell and spindle fibers attach to sister chromatids’ centromeres
12. Meiosis II: Anaphase IIThe sister chromatids are pulled to opposite sides of the pole by the spindle fibers.
13. Meiosis II: Telophase IIThe nuclear envelope forms around each set of chromosomesFour unique haploid (1n) cells are formed
14. Genetic Variation Created____________ ____________: the random distribution of homologous chromosomesEach of the 23 pairs of chromosomes separate independently of each other Thus, 223 (over 8 million) gametes can be produced by a single cellGamete formation endless possibilities 223 x 223 = over 64 trillion unique zygotesExtremely important to the evolution of all species.
15. MeiosisMalesSpermatogenesis: sperm production FemalesOogenesis: egg (ova) production
16. FertilizationGametes of opposite sexes join to make a diploid (2n) zygoteZygote: cell resulting from the fusion of gametes