Rec8 is a protein that is found bound to yeast chromosomes at certain points in
ID: 5931 • Letter: R
Question
Rec8 is a protein that is found bound to yeast chromosomes at certain points in cell division. Rec8 exists throughout meiosis I but breaks down at anaphase II. When the gene that encodes Rec8 is mutated, sister chromatids separate in anaphase I.A)From these observations, propose a mechanism for the role of Rec8 in meiosis that explains why sister chromatids normally separate in anaphase II but not in anaphase I.
B)Make a prediction about whether or not Rec8 is present in prophase of mitosis and whether or not it is present in anaphase of mitosis.
Explanation / Answer
From the given information, the function of Rec8 is to keep sister chromatids together. If the gene that code for Rec8 mutated it loses its function. And the lose of this function causes separation of sister chromatids in meiosis I, instead of meiosis II (anaphase II). This early separation of sister chromatids causes aneuploidy (abnormal number of chromosomes) in the gamet cells. There will be no meiosis II because the sister chromatides has already separated causing nondisjunction. 2) In a perfect sistuation, there will Rec8 in prophse of mitosis to keep the sisterchromatids together until they align at the senter (metaphase) and separate to move to the oposite poles (anaphase)But after/during anaphase the Rec8 should be breakdown to keep the chromatids separated. So, there will be no Rech8 in anaphase of mitosis.
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