Supplementary videos

• Meiosis and sex determination: XX males and XY females
• Evolution of Y chromosome: adventures of crossing-over
• Evolution of human chromosome #2 (Ken Miller): why do humans have 46 chromosomes?
• Calico cat and X inactivation (random deactivation of an X chromosome)

Extra credit readings

• The Effect of Female Hormone Fluctuations on the Incidence of Trisomy in Humans FGCU 98
• X-inactivation profile Nature 3/17/05

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