Ch-15-Test-Questions no diagram

That a son will be a hemophiliac if the couple has

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daughter of this mating will be a hemophiliac? That a son will be a hemophiliac? If the couple has four sons, what is the probability that all four will be born with hemophilia? Answer: 0 ; 1⁄2, 1/16 17 2) Pseudohypertrophic muscular dystrophy is an inherited disorder that causes gradual deterioration of the muscles. It is seen almost exclusively in boys born to apparently normal parents and usually results in death in the early teens. Is this disorder caused by a dominant or a recessive allele? Is its inheritance sex‐linked or autosomal? How do you know? Explain why this disorder is almost never seen in girls. Answer: R ecessive; if the disorder were dominant, it would affect at least one parent of a child born with the disorder. The disorder's inheritance is sex‐linked because it is seen only in boys. For a girl to have the disorder, she would have to inherit recessive alleles from both parents. This would be very rare, since males with the recessive allele on their X chromosome die in their early teens. 3) Red‐green color blindness is caused by a sex‐linked recessive allele. A color‐blind man marries a woman with normal vision whose father was color‐blind. What is the probability that they will have a color‐blind daughter? What is the probability that their first son will be color‐blind? (Note the different wording in the two questions.) Answer: 1 ⁄4 for each daughter (1⁄2 chance that child will be female x 1⁄2 chance of a homozygous recessive genotype); 1⁄2 for first son. 4) A wild‐type fruit fly (heterozygous for gray body color and normal wings) is mated with a black fly with vestigial wings. The offspring have the following phenotypic distribution: wild type, 778; black‐vestigial, 785; black‐normal, 158; gray‐vestigial, 162. What is the recombination frequency between these genes for body color and wing size? Answer: 1 7% 5) In another cross, a wild‐type fruit fly (heterozygous for gray body color and red eyes) is mated with a black fruit fly with purple eyes. The offspring are as follows: wild type, 721; black‐purple, 751; gray‐purple, 49; black‐red, 45. What is the recombination frequency between these genes for body color and eye color? Using information from problem 4, what fruit flies (genotypes and phenotypes) would you mate to determine the sequence of the body‐color, wing‐size, and eye‐color genes on the chromosome? Answer: 6 %. Wild type (heterozygous for normal wings and red eyes) × recessive homozygote with vestigial wings and purple eyes 18 6) A fruit fly that is true‐breeding for gray body, vestigial wings (b+ b+ vg vg) is mated with one that is true‐breeding for black body, normal wings (b b vg+ vg+). A) Draw the chromosomes for each P generation fly, showing the position of each allele.
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B) Draw the chromosomes and label the alleles for an F1 fly.
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