Steps of Meiosis

Steps of Meiosis - kinetochores only connect to centromeres...

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Steps of Meiosis prophase I - DNA coils and becomes visible under light microscopes sister chromatid cohesion - pairing of homologous pairs side by side o guided by heterochromatin sequences o homologues attach to nuclear envelope at specific sites recombination nodules - has enzymes for breaking/joining homologous chromatids crossing over between sister chromatids is suppressed only about 2-3 crossovers per chromosome per meiosis sister chromatids held together at centromeres, homologous chromosomal pairs held together where crossing over took place chiasma - X-shaped structure where crossover took place o ensures that the microtubule spindle only attaches to 1 side of centromere o indicates that crossing over has taken place metaphase I - nuclear envelope dissolves microtubules form spindle like in mitosis terminal chiasmata - state of chiasmata where they reach the ends of the chromosomes
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Unformatted text preview: kinetochores only connect to centromeres on 1 side • chromosome pairs line up on metaphase plate randomly anaphase I- microtubules begin to shorten • chiasmata gets broken, homologues get pulled apart • sister chromatids aren’t split up • independent assortment- poles can have mixes of maternal/paternal homologues telophase I- chromosomes located in clusters at each pole • nuclear membrane reforms around chromosomes, each w/ 2 sister chromatids • sister chromatids no longer identical due to crossing over meiosis II- occurs after a brief interphase after meiosis I • prophase II - nuclear membrane breaks down, microtubule spindle forms • metaphase II - spindle fibers bind to both sides of centromeres • anaphase II - sister chromatids split, go to opposite poles • telophase II - nuclear envelope re-forms • meiosis I/II result in 4 distinct cells w/ haploid chromosomal set...
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This note was uploaded on 01/04/2012 for the course BSC BSC1005 taught by Professor Orlando,rebecca during the Fall '10 term at Broward College.

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