14 May 2010 Friday

14 May 2010 Friday - Lecture notes genetics 14 May 2010...

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Unformatted text preview: Lecture notes genetics 14 May 2010 Mendels monohybrid crosses 1. Mendel began by examining the inheritance of individual pairs of traits, one pair at a time (these were his MONOHYBRID CROSSES: the parents different with respect to one set of characteristics a. Example: he crossed a purple-petaled plant with a white-petaled plant b. PPxpp, the F1 generation were all Pp purple plants c. Self pollination of the F1xF1 plants ended up with 3 purple and one white plants 2. Repeating this type of cross with other traits, he obtained a similar result- one phenotype disappeared in the F1 and reappeared in the F2, and the two phenotypes appeared in a 3:1 ratio a. Example: yellow pea producing plant x green pea producing plant b. F1= all yellow c. F2= yellow, green d. Recessive trait: disappeared hidden in presence of dominant allele, reappeared in F2 generation (expressed when homozygous) Mendels test crosses: question: one trait disappeared in the F1 generation, only to reappear,...
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