BS 50 Genetics and Genomics Week of Oct 3 Additional Practice Problems for Section. A/a ; B/B ; d/d X A/a ; b/b ; D/d

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1 BS 50 Genetics and Genomics Week of Oct 3 Additional Practice Problems for Section 1. In the following cross, all genes are on separate chromosomes. A is dominant to a, B is dominant to b and D is dominant to d. What proportion of the progeny will be A/a? A/a ; B/B ; d/d X A/a ; b/b ; D/d phenotypically A? phenotypically a? phenotypically B? b/b? D/d? a/a ; d/d? A/a ; D/d? phenotypically A D? a/a ; B/b; d/d? A/a ; B/b ; D/d? phenotypically a B D?

2 2. This human pedigree describes the inheritance of a rare single gene hereditary disease. The # and * symbols indicate individuals addressed in the problem; these symbols do not indicate anything about the genotype. # a. What possible genotype(s) does the unaffected female denoted with (#) have? b. What possible genotype(s) does the unaffected male denoted with an asterisk (*) have? Unaffected male * is a polygamist with three wives. One of his wives is homozygous for the dominant allele, another is homozygous recessive, and the third is heterozygous. He has four children by each of the wives, and none of the children are identical twins. All twelve children are unaffected. c. What is male * s most likely genotype? Why? Be quantitative with your answer. d. Are you certain of the genotype in part c? Why or why not?

3 3. A diploid organism has a somatic chromosome number of 10. a. How many chromosomes are present per cell at the following stages of cell division: Metaphase of Mitosis Metaphase I of Meiosis Metaphase II of Meiosis b. A unique labeling technique is used such that all paternally-derived centromeres are labeled blue and all maternally-derived centromeres are labeled red. What is the probability that a gamete from an individual stained with this labeling technique will contain only red centromeres? (you can leave your answer in the form of a reduced fraction or equation) c. What is the probability that a gamete from an individual stained with this labeling technique will contain exactly 3 blue and 2 red centromeres? (you can leave your answer in the form of a reduced fraction or equation)

4 4. (18 pts) The following questions refer to the pedigree below. Assume that all individuals marrying into the pedigree are homozygous normal unless there is evidence that indicates otherwise. A) Is this trait dominant or recessive? Explain. B) Is this trait autosomal or sex linked? Explain. C) What is the probability that the first child born to individuals R & S will be affected?

5 5. (18 pts) Complete the following statements using as many of the choices as are appropriate: A) mitosis B) meiosis I C) meiosis II D) none (not mitosis nor meiosis I or II) i.) The spindle apparatus is present in cells undergoing. ii.) Reduction in ploidy occurs at. iii.) Pairing of nonhomologous chromosomes is a feature of. iv.) Centromeres divide during. v.) Sister chromatids divide during. 6. You have one strain of moth that is pure-breeding for light wings and another strain that is pure-breeding for dark wings. You cross a light-winged female with a dark-winged male and find that all F1 progeny have dark wings. You then cross the F1 individuals to each other and find that all the males have dark wings, half the females have light wings, and half the females have dark wings. Explain this result. What result would you expect for the F1 and F2 generation from the reciprocal cross (darkwinged female crossed to a light-winged male)?