Lecture Assignment 4

Lecture Assignment 4 - Starchy X waxy 784 starchy Starchy X...

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Biology 202 Lecture Homework 4 Due in Discussion Class - Week 6 (Feb. 20-Feb. 24) 1. Human albinism is a condition arising from an inability to manufacture the pigment melanin. This disorder is due to the expression of an allele, a , which is recessive to the allele for normal pigmentation, A . Identify the possible genotypes of both parents and progeny in the following situations. a. Albino parents who have only albino children. b. An albino woman and a normal man who have two albino and two normal children. c. Phenotypically normal parents who have both normal and albino children. 2. In corn, a food-storing part of the seed known as the endosperm may be starchy or waxy. The allele for starchy endosperm, W , is dominant to the allele for waxy endosperm, w . For each of the following crosses, indicate the genotypes for the parents and F 1 progeny. Parents F 1 Progeny Starchy X starchy 682 starchy Starchy X starchy 506 starchy : 162 waxy (3:1)
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Unformatted text preview: Starchy X waxy 784 starchy Starchy X waxy 425 starchy : 409 waxy 3. In humans, nearsightedness and the enzyme disorder PKU are both inherited as recessive traits. Designate letters for the alleles for normal vision, nearsightedness, PKU and non-PKU (normal). A phenotypically normal man who carries recessive alleles for both traits marries a woman who has the same genotype with regard to these traits. What are the expected phenotypes and frequencies for their progeny? 4. A daughter of the couple described above is nearsighted and heterozygous for the normal enzyme. Her husband has the normal phenotypes for both traits, although his father was nearsighted and his mother had PKU. a. What is the genotype of the husband? b. What is the probability that a child of this couple is nearsighted and has PKU? c. What is the probability that a child of this couple is heterozygous for both traits?...
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