Michael Bow, Ralph Jordan Montfort, Anup Shah, Christopher Siess
14. The pedigree below traces the inheritance of alkaptonuria, a biochemical disorder. Affected individuals, indicated here by the colored circles and squares, are unable to break down a substance called alkapton, which colors the urine and stains body tissues. Does alkaptonuria appear to be causes by a dominant allele or by a recessive allele? Fill in the genotypes of the individuals whose genotypes can be deduced. What genotypes are possible for each of the other individuals?
Alkaptonuria appears to be a recessive allele.
George- Aa
Arlene- aa
Sandra- Aa
Tom- aa
Sam- Aa
Wilma- aa
Ann- Aa
Michael- Aa
Daniel- Aa
Alan- Aa
Tina- AA
Carla- aa
Christopher- AA
15. A man has six fingers on each hand and six toes on each foot. His wife and their daughter have the normal number of digits. Extra digits are a dominant trait. What fraction of this couple’s children would be expected to have extra digits?
F / ff / Ff / ff
f / Ff / ff
2 out of 4 children are expected to have extra digits.
16. Imagine that you are a genetic counselor, and a couple planning to start a family comes to you for information. Charles was married once before, and he and his first wife had a child with cystic fibrosis. The brother of his current wife Elaine died of cystic fibrosis. What is the probability that Charles and Elaine will have a baby with cystic fibrosis? (Neither Charles nor Elaine have cystic fibrosis)
C / cC / CC / Cc
c / Cc / cc
1 (Has cystic fibrosis): 2 (Carrier) : 1 (No cystic fibrosis)
C / cC / CC / Cc
C / CC / Cc
2 (Has cystic fibrosis) : 2 (Carrier)
1/8 possibility to have a baby with cystic fibrosis.
17. In mice, black color (B) is dominant to white (b). At a different locus, a dominant allele (A) produces a band of yellow just below the tip of each hair in mice with black fur. This gives a frosted appearance known as agouti. Expression of the recessive allele (a) results in a solid coat color. If mice that are heterozygous at both loci are crossed, what is the expected phenotypic ratio of their offspring?
BA / Ba / bA / BaBA / BBAA / BBAa / BbAA / BbAa
Ba / BBAa / BBaa / BbAa / Bbaa
bA / bBAA / bBAa / bbAA / bbAa
Ba / bBAa / bBaa / bbAa / bbaa
1 (Total black with agouti): 9 (Phenotypically black with agouti): 1 (Total black without agouti) : 2 (Phenotypically black without agouti): 2 (White, carrying agouti): 1: (White, not carrying agouti)