Ch%2027%20Male%20Reproduction%20Lecture%20Presentation%20Fall%2c%202011-1

723 meiosistelophasei meiosistelophasei

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Unformatted text preview: f homologous chromosomes Gametes only have 23 chromosomes and are said to be haploid (n chromosomal number) Gamete formation is by meiosis, in which the number of chromosomes is halved (from 2n to n) Figure 27.8b, c Figure 27.6 Meiosis – Interphase Meiosis – Interphase Two nuclear divisions halve the number of chromosomes Chromosomes replicate prior to meiosis I Figure 27.7.1 Meiosis – Prophase I Meiosis – Prophase I Homologous chromosomes undergo synapsis Tetrads are formed with homologous partners Crossing over takes place during prophase I Figure 27.7.2.1 Meiosis – Metaphase I Meiosis – Metaphase I Tetrads line up at the spindle equator during metaphase I Figure 27.7.2.2 Meiosis – Anaphase I Meiosis – Anaphase I Homologous chromosomes composed of joined sister chromatids are distributed to opposite ends of the cell Figure 27.7.2.3 Meiosis – Telophase I Meiosis – Telophase I Nuclear membrane forms around chromosomal masses Spindle break down Chromatin reappears With telophase and cytokinesis completed, two haploid daughter cells are formed (with 2n amount of DNA) Figure 27.7.2.4 Meiosis II Meiosis II Mirrors mitosis except that chromosomes are not _________ before it begins Meiosis accomplishes two tasks: It reduces the chromosome number by ____ (2n to n) It introduces genetic variability Meiotic Cell Division: Meiosis II Meiotic Cell Division: Meiosis II Figure 27.7.3 Spermatogenesis Spermatogenesis Cells making up the...
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This note was uploaded on 09/13/2011 for the course BIOL 2401 taught by Professor Rameriz during the Spring '11 term at University of Texas at Dallas, Richardson.

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