week+7+problems+key - Question 1: The dominant phenotype is...

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Unformatted text preview: Question 1: The dominant phenotype is black fur and the recessive is albino (white). Genotypes: Black hamster 1: BB Black hamster 2: Bb Albino: bb Offspring of black hamster 1 and the albino (BB X bb) = all Bb Offspring of black hamster 2 and the albino (Bb X bb) = 50% Bb and 50% bb Question 2: Recombination Frequencies: A-B: 18% (18 map units) A-D: 8 % (8 map units) B-D: 12 % (12 map units) 12 8 A__________________D_____________________B 20 Question 3: It is a recessive disease: one piece of evidence is that the disease skips two generations It is inherited on an autosome (non-sex chromosome). It is not x-linked since the father in the 3rd generation (the one with the *) is unaffected yet his daughter is. Since the disease is recessive, the daughter would have to receive an X chromosome with the recessive allele from each parent. Since her father does not have the disease, he cannot contribute an X chromosome carrying the recessive allele. Question 3 (cont.) Both parents in the 3rd generation are carriers of the recessive allele. If they have another child, there is a 75% chance that they will not have the disease. This is because both homozygous and heterozygous dominant genotypes yield the nondisease phenotype. Only 25% of the offspring will have the homozygous recessive genotype. Since the disease is not sex-linked, it doesnt matter if they have a boy or girl. N N n NN Nn n Nn nn Question 4 Determine the probability that the offspring will have the required genotype for each gene. For number 1: AABBCC X aabbcc ---- AaBbCc A a a Aa Aa B b b Bb Bb C c c Cc Cc A Aa Aa B Bb Bb C Cc Cc Chance of getting Aa genotype = 1 Chance of getting Bb genotype = 1 Chance of getting Cc genotype = 1 Chance of getting all 3 at the same time: 1X1X1=1 All offspring will have the AaBbCc genotype For number 2: aaBbCC x AABbcc ------AaBbCc a A A Aa Aa B B b BB Bb C c c Cc Cc a Aa Aa b Bb bb C Cc Cc 50% or 1/2 of the offspring will have the AaBbCc genotype Chance of getting Aa genotype = 1 Chance of getting Bb genotype = 1/2 or 0.5 Chance of getting Cc genotype = 1 Chance of getting all 3 at the same time: 1 X 1/2 X 1 = 1/2 ...
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This note was uploaded on 11/22/2010 for the course BIOLOGY SC Bio Sci 93 taught by Professor Dr.dianeo'dowdanddr.rahulwarrior during the Fall '10 term at UC Irvine.

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