University:
Amherst College
Course:
BIOL 303 | Molecular Neurobiology: CURE
Academic year:

2010
Views:

253

Pages:

9
Author:

suluhugx2

Chemical Biology 03 Dec 12(oops! -13), 2010 Inheritance IV (inheritance of genes on X or Y) Consider multiple genes at a time: AaBbCcDd x AaBbCcDd What proportion of offspring will be AAbbCcDd ? 1) Punnett Square? How many different gametes from each parent? 2 possible alleles for 4 genes: 24 = 16 2) Abreviated Branch Diagram (one gene at a time) Prob of AA 1/4 prob of bb 1/4 prob of Cc 1/2 prob of Dd 1/2 = 1/64 Human karyotypes Y y XY = o heterogametic XX = o homogametic function as homologous pair during meiosis Human karyotypes The Y chromosome: Y XY = y o function as homologous pair during meiosis PseudoAutosomal Region Genes on the Y chromosome: Inheritance of Y-linked gene mutation: •Can females be affected? •Can females be carriers? •Can males be carriers? •What is the probability that an affected male will pass the condition on to sons? His daughters? •What is the probability that an affected male will have a child with the condition? Genes on X chromosomes o Female = XX Genes on X can be homozygous or heterozygous Y O Male = XY Almost all genes on X are hemizygous Look at inheritance pattern: Example: X-linked recessive trait: Duchenne Muscular Dystrophy d XX D D XY Y d XY Mom is a carrier and Dad is unaffected D XY D D XX d XX D Daughters are never affected Sons have 50% chance D Dd x Mom DY Dad D d Y X-linked Hemophelia in European Royal Families Look at inheritance pattern: Example: X-linked dominant trait: Amelogenesis imperfecta (tooth defect) a a XY Y XX a a XY A a XY A XX a XX A If Dad is affected All daughters are affected Sons are never affected

Chemical Biology 03 Inheritance IV

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