September 20-ch11

September 20-ch11 - September 20, 2007 Chapter 11 Summary...

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Unformatted text preview: September 20, 2007 Chapter 11 Summary of Meiosis II Meiotic Prophase II o Spindle microtubules reform and capture duplicated chromosomes o Each chromatic contains kinetochore Meiotic Metaphase II o Duplicated chromosomes line up single, perpendicular to the spindle Meiotic Anaphase II o Chromatic separate Meiotic Telophase II o Cytokinesis occurs, nuclear membranes reform, chromosomes relax Mitosis and Meiosis in life cycles of eukaryotes o Organisms that are predominantly diploid Haploid life cycle o Fungi and unicellular organisms Genetic Variability o Meiosis and sexual reproduction are a rich source of genetic variability Recombination: crossing over creates novel gene combinations Reassortment: shuffling or homologues creates novel chromosome combinations Fusion of gametes, in restoring the "2n" state, adds further genetic variability Novel Chromosome Combinations o Mutations produce new variation but are rare occurrences o Genetic variability o Sexual recombination allows rare mutations to come together, or separate, in various combinations o Reassortment: randomized line up and separation of homologous chromosomes in Meiotic Metaphase I and Anaphase I increase variation The number of possible combinations is "2N" where n = number of homologous pairs Gamets from two humans could produce about 64 trillion 2n pairs ...
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This note was uploaded on 04/10/2008 for the course BIOLOGY 101 taught by Professor Beitch during the Spring '07 term at Quinnipiac.

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