1. (8 points) Anhydrotic ectodermal dysplasia is an X-linked recessive disease in cattle, causing tooth abnormalities and hairlessness. Arachnomelia is an autosomal recessive condition that causes spider legs in newborn calves. Use âDâ to indicate the dominant, normal teeth and hair in cattle and âdâ for the dysplasia. Use âLâ for normal legs and âlâ for spider legs. Suppose a heifer having normal teeth and hair and normal legs but whose sire had dysplasia and spider legs is backcrossed to her sire.
a. What are their genotypes?
b. What are the genotypes, phenotypes, and genotypic and phenotypic proportions we expect in their progeny?
2. (6 points) In German Shepherds, hemophilia A is an X-linked recessive disease, affecting the blood clotting times in dogs having the disease. Use â+â to indicate the normal, normal blood clotting time allele and âaâ for the hemophilia allele. A bitch (female) who has normal blood clotting times and whose sire (male) had hemophilia A is mated with a sire with normal blood clotting times but whose sire also had hemophilia A.
a. What are the genotypes of the 4 dogs described in the problem?
b. What are the genotypes, phenotypes, genotypic and phenotypic proportions you would expect to observe in the puppies produced from this cross?
3. (8 points) In turkeys, inhibited feathering is a sex-linked dominant gene (F). Use âfâ to denote the normal feathering allele. Suppose a bald hen (female) is crossed with a normally feathered rooster.
a. What are the genotypes of the two birds described?
b. What are the genotypes, phenotypes, genotypic and phenotypic proportions expected in the F1 progeny? c. What will be the genotypes, phenotypes and proportions produced when the F1 males are backcrossed?
4. (8 points) In guinea pigs, short hair (H) is dominant to long hair (h) and the heterozygous condition when you cross a yellow coat (CY) and white coat (CW) gives you a cream coat. These two loci are located on different chromosomes. A heterozygous short-haired cream guinea pig is crossed to a long-haired white guinea pig.
a. What are the genotypes, phenotypes and proportions of the pups (baby guinea pigs) produced?
b. What are the genotypes, phenotypes and proportions expected if we crossed the heterozygous short- haired cream guinea pig with a heterozygous short-haired yellow guinea pig?
1. (8 points) Anhydrotic ectodermal dysplasia is an X-linked recessive disease in cattle, causing tooth abnormalities and hairlessness. Arachnomelia is an autosomal recessive condition that causes spider legs in newborn calves. Use âDâ to indicate the dominant, normal teeth and hair in cattle and âdâ for the dysplasia. Use âLâ for normal legs and âlâ for spider legs. Suppose a heifer having normal teeth and hair and normal legs but whose sire had dysplasia and spider legs is backcrossed to her sire.
a. What are their genotypes?
b. What are the genotypes, phenotypes, and genotypic and phenotypic proportions we expect in their progeny?
2. (6 points) In German Shepherds, hemophilia A is an X-linked recessive disease, affecting the blood clotting times in dogs having the disease. Use â+â to indicate the normal, normal blood clotting time allele and âaâ for the hemophilia allele. A bitch (female) who has normal blood clotting times and whose sire (male) had hemophilia A is mated with a sire with normal blood clotting times but whose sire also had hemophilia A.
a. What are the genotypes of the 4 dogs described in the problem?
b. What are the genotypes, phenotypes, genotypic and phenotypic proportions you would expect to observe in the puppies produced from this cross?
3. (8 points) In turkeys, inhibited feathering is a sex-linked dominant gene (F). Use âfâ to denote the normal feathering allele. Suppose a bald hen (female) is crossed with a normally feathered rooster.
a. What are the genotypes of the two birds described?
b. What are the genotypes, phenotypes, genotypic and phenotypic proportions expected in the F1 progeny? c. What will be the genotypes, phenotypes and proportions produced when the F1 males are backcrossed?
4. (8 points) In guinea pigs, short hair (H) is dominant to long hair (h) and the heterozygous condition when you cross a yellow coat (CY) and white coat (CW) gives you a cream coat. These two loci are located on different chromosomes. A heterozygous short-haired cream guinea pig is crossed to a long-haired white guinea pig.
a. What are the genotypes, phenotypes and proportions of the pups (baby guinea pigs) produced?
b. What are the genotypes, phenotypes and proportions expected if we crossed the heterozygous short- haired cream guinea pig with a heterozygous short-haired yellow guinea pig?
