A pedigree is shown below. Match the pedigree with the most likely mode of inher

Question

A pedigree is shown below. Match the pedigree with the most likely mode of inheritance. a. autosomal dominant b. autosomal recessive c. X-linked recessive d. X-linked dominant e. mitochondrial Sickle-cell disease is the result of a single nucleotide substitution that produces a single amino acid substitution. This is best described as a a. frameshift mutation b. nonsense mutation c splice-site mutation d. missense mutation e. none of the above What is the probability that a male will inherit an X-linked recessive allele from his father who is phenotypically normal? a. 0% b. 25% c. 50% d. 75% e. 100% Loci A and B are linked. Two heterozygotes are crossed. Individual one makes gametes in which both alleles in the gamete are either dominant or recessive (i.e. AB). The other organisms makes gametes in which the alleles are mixed (i.e. Ab). If NO crossover takes place, what is the expected genotype ratio? a. 1: 1 b. 3: 1 c. 1: 2: 1 d. 9: 3: 3: 1 e. 1: 1: 1: 1

Explanation / Answer

7. The pedigree shows autosomal dominant type of inheritance. In this case, the affected son of non founding parents has an affected father indicating that the disease is autosomal dominant. A father cannot transfer X-linked alleles to his son , so the disease cannot be X-linked dominant.

Hence, the correct option is (A).

8. Sickle cell disease is the result of a single nucleotide substitution that produces a single aminoacid substitution. This is best described as missense mutation or single point mutation. The mutation occurs in the beta hemoglobin gene that converts a GAG codon into GUG that encodes the aminoacid valine rather than glutamic acid .

Hence, the correct option is (D).

9. The probability that the male will inherit an X-linked recessive allele from his father who is normal is 0% because a male receives an Y-chromosome from his father, but not an X-chromosome.

Hence, the correct option is (A).

10. Genotypic ratio is the letters that make up an individual . For example, AB or Ab

If no crossover takes place, the expect genotypic ratio would be 1:1:1:1 because the two genes are not linked.

Hence, the correct option is (E).

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