Lecture 7 (deleted 4f50fb8f-1dc8ae-5a2a49fd)

Lecture 7(deleted 4f50fb8f-1dc8ae-5a2a49fd)

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Unformatted text preview: 19 Turner’s Syndrome (XO) 1/3000 female births Note: No known cases in which a person is missing both X chromosomes One X is required for human development; two Xs for fer1lity 20 10 2/14/12 Klinefelter’s Syndrome (XXY, XXXY, XXYY) 1/1000 male births A single copy of the Y, even with mul1ple Xs, leads to male phenotype 21 Poly ­X Syndrome (XXX, XXXX) There are seldom any observable physical anomalies in Triple X females 1/1000 female births Triplo ­X syndrome Note: More X chromosomes lead to higher risk and severity of mental retarda1on Addi1onal copies of the X can disrupt normal development 22 11 2/14/12 Poly ­Y Syndrome (XYY) Controversy! There are seldom any observable physical anomalies in double Y males “Supermale” syndrome Richard Speck Mass murderer Chicago 1960’s 1/1000 male births Addi1onal copies of the Y can result in mild phenotypic effects (mischaracterized as causing aggressive or criminal behavior) 23 Concept check 1: The sex of an individual is best defined by: A. their number of sex chromosomes. B. sexual phenotype, such as size of gametes. C. the ploidy of their body cells. D. the presence or absence of a Y chromosome. E. their behavioral characteris1cs. Sexual reproduc)on = produc1on of offspring that are gene1cally dis1nct from their parents (usually 2 sexes: males with small gametes and females with large gametes) 24 12 2/14/12 Chromosomal sex determina1on in Drosophila XX XY XO XXY XXX XX XO Male: XY Female: XX AA AA 1.0 0.5 Female Male AA AA AA AAA AAA 0.5 1.0 1.5 0.67 0.33 Male Female Metafemale Intersex Metamale Intersex = traits from both males and females Metamale = weak and sterile male Metafemale = serious developmental problems 0.5 = male and 1.0 = female 0.5 ­1.0 = intersex >1.0 metafemale &...
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This note was uploaded on 01/30/2013 for the course BIO LS1B taught by Professor Andrewberry,hopihoekstra,maryellenruvolo during the Spring '12 term at Harvard.

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