Discussion Section michelle wk 6 p2

Discussion Section michelle wk 6 p2 - B ICD 100- Genetics...

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BICD 100- Genetics Ghiara Spring 08 Week 6 Tuesday lecture –X and Y chromosomes History of X-Chromosome Hermann Henking (1891) first discovered the X-chromosome; called it the “X-Body” Clarence McClung saw the X-chromosome in grasshoppers; called it “Accessory chromosome” and eventually changed it to “X-Chromosome” Nettie Stevens and Edmund Wilson (1905) discovered the XX-XO system in grasshoppers o XX = Female HOMOGAMETIC o XO = Male HETEROGAMETIC When male and female cross, there is a 1:1 ratio of getting a boy or girl for offspring. Yet, there are biochemical conditions within the sperm itself that can make a certain type of gamete (X or Y) to be more preferable—thus could be a reason why offspring is more susceptible to being girls other than boys or vice versa. YO does not and cannot exist. Why? Y-Chromosome How do males get determined? SRY-gene = Sex Determining Region Y; this gene only exists on the Y chromosome. o
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This note was uploaded on 01/25/2011 for the course BICD 100 taught by Professor Nehring during the Spring '08 term at UCSD.

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Discussion Section michelle wk 6 p2 - B ICD 100- Genetics...

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