Lecture 6 Questions

Lecture 6 Questions - Lecture 6 Study Questions 1 How do incomplete dominance and codominance differ 2 What is incomplete penetrance and what

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Lecture 6 : Study Questions 1. How do incomplete dominance and codominance differ? 2. What is incomplete penetrance and what causes it? 3. What is gene interaction? What is the difference between an epistatic gene and a hypostatic gene? 4. What is a recessive epistatic gene? 5. What is a complementation test and what is it used for? 6. What characteristics are exhibited by a cytoplasmically inherited trait? 7. Palomino horses have a golden yellow coat, chestnut horses have a brown coat,and cremello horses have a coat that is almost white. A series of crosses between thethree different types of horses produced the following offspring: palomino X palomino = 13 palomino, 6 chestnut, 5 cremello chestnut X chestnut = 16 chestnut cremello X cremello = 13 cremello palomino X chestnut = 8 palomino, 9 chestnut palomino X cremello = 11 palomino, 11 cremello chestnut X cremello = 23 palomino a. Explain the inheritance of the palomino, chestnut, and cremello phenotypes in horses. b. Assign symbols for the alleles that determine these phenotypes and list the genotypes of all parents and offspring given in the preceding table. 8. The L M and L N alleles at the MN blood group locus exhibit codominance. Give the expected genotypes and phenotypes and their ratios in progeny resulting from the following crosses: a. L M L M X L M L N b. L N L N X L N L N c. L M L N X L M L N d. L M L N X L N L N e. L M L M X L N L N 9. Assume that long ear lobes in humans are an autosomal dominant trait that exhibits 30% penetrance. A person who is heterozygous for long ear lobes mates with a person who is homozygous for normal ear lobes. What is the probability that their first child will have long ear lobes? 10. The eastern mosquito fish ( Gambusia affinis holbrooki ) has XX-XY sex determination. Its spotting is inherited as a Y-linked trait. The trait exhibits 100% penetrance when the fish are raised at 22° C, but the penetrance drops to 42% when the fish are raised at 26° C. A male with spots is crossed with a female without spots, and the F1 are intercrossed to produce the F2. If all the offspring are raised at 22° C, what proportion of the F1 and F2will have spots? If all the offspring are raised at 26° C, what proportion of the F1 and F2 will have spots?
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11. When a Chinese hamster with white spots is crossed with another hamster that has no spots, approximately 1/2 of the offspring have white spots and 1/2 have no spots. When two hamsters with white spots are crossed, 2/3 of the offspring possess white spots and 1/3 have no spots. a. What is the genetic basis of white spotting in Chinese hamsters?
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This note was uploaded on 05/07/2011 for the course BIOLOGY 352 taught by Professor Townsend during the Spring '08 term at San Diego State.

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Lecture 6 Questions - Lecture 6 Study Questions 1 How do incomplete dominance and codominance differ 2 What is incomplete penetrance and what

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