LIFESCI 2G03 Lecture Notes - Lecture 10: Y Chromosome, Karyotype, Sister Chromatids
23 Mar 2018
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Ensuring that there"s 1 woman in that family and 1 man in that family. It wasn"t a random sample, it was excluding some data points. Disjunction: seperation and segreation of chromosomes to two daughter cells: the pulling apart of homologues (meiosis ii) or sister chromatids (mitosis, meiosis i) Non-disjunction: when seperation and segeration do not occur: non-disjunction (ndj) can happen during both mitosis and meiosis, to any chromosomes. Cells with extra copy of chromosome (2 long and one short) = non disjunction. As mother"s age increases, risk of down syndrome also increases. Eggs can be sitting in meiosis for 16, 40 years etc. With time aligned homologues fall apart = increase in meisosis i non disjunction with age. Things can be toxic, causes non-disjunction to occur. Non disjunction in meiosis i or meiosis ii. Results in an egg with two x chromosomes, then pairing with a sperm that donates another x results in three x.
