Question

2
select the correct answer from each drop - down menu.
marfan syndrome is a genetic disorder that affects connective tissue, leading to abnormal skeletal development, lens deformities in the eyes, and heart complications. the disorder is caused by a mutation in the fbn1 gene. the following dna sequences show a section of the fbn1 gene in an unaffected individual and an individual with marfan syndrome.
unaffected individual: ccg - ccg - ctt
individual with marfan syndrome: cgg - ccg - ctt
marfan syndrome is an autosomal dominant disorder, so the mutation that causes it is

mutation. according to the dna sequences shown, marfan syndrome can be caused by a

mutation in the fbn1 gene. this mutation is likely a

mutation.

Explanation:

1. Autosomal dominant disorders are caused by mutations in non-sex (autosomal) chromosomes, and the altered allele is dominant over the normal one, so this is an autosomal dominant mutation.
2. Comparing the DNA sequences: Unaffected is CCG-CCG-CTT, affected is CGG-CCG-CTT. Only a single nucleotide (C → G in the first codon) is changed, so this is a point mutation.
3. A point mutation that changes one nucleotide, leading to a different amino acid being coded (since CCG codes for proline, while CGG codes for arginine) is a missense mutation.

Answer:

1. autosomal dominant
2. point
3. missense