MBG 2040 Lecture Notes - Lecture 6: Homologous Chromosome, Ploidy, Fundamental Theorem Of Arithmetic
27 Nov 2017
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3. 2: chromosomes do not pair up correctly in meiosis, may reproduce asexually. 2n = 52; old world cottons from asia and african (2n = 26) were crossed with american. In animals, sterile offspring are produced because chromosome doubling is not well tolerated: donkey (2n = 62) crossed with horse (2n = 64) to produce mule (2n = 63) Aneuploidy: diploid genome which lacks a chromosome or has an extra chromosome. Aneuploidy of sex chromosomes: common compared to trisomies of autosomes, better tolerated by body and can inactivate extra chromosomes to maintain more normal function. Individuals are usually sterile: sex organs do not develop normally. Imbalanced hormones: common syndromes, xo = turner syndrome (single x); have 45 chromosomes, xxy = klinefelter syndrome, xxx = triple x syndrome; female cells will inactivate extra x chromosomes, xyy = double y males. Correlation between incidence of trisomies and maternal age:
