LIFESCI 7B Chapter Notes - Chapter 2: Y Chromosome, Zygosity, Wild Type
4 Sep 2018
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Document Summary
For x & y sex chromosomes, reciprocal crosses are not equivalent. Segregation of sex chromosomes predicts 1:1 ratio of females to males. Apparently, females are slightly less likely to survive from conception to birth: males are slightly less likely to survive from birth to reproductive maturity. Sex of each birth is random relative to previous birth. In animals, sex is genetically determined and associated with chromosomal differences. X chromosome is more than 150 mb long, and y is 50 mb long. Tips of x and y share a small region (~2. 7 mb on short arm and 0. 3 mb near long arm) of homology. These regions allow chromosomes to pair during meiosis. Size and gene content of x and y differ among species. X-linked inheritance discovered thru studies of male fruit ies with white eyes: wild type: most common phenotype. Genes in the x chromosome exhibit a "criss cross" inheritance pattern.
