Question

2
select the correct answer from each drop - down menu.
marfan syndrome is a genetic dis... ng to abnormal skeletal development, lens deformities in the eyes, and heart complications. the disorder is cau... a following dna sequences show a section of the fbn1 gene in an unaffected individual and an individual with m...
options for one blank: deletion, substitution, insertion
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.
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Explanation:

1. First, compare the DNA sequences: Unaffected is CCG-CCG-CTT; Marfan is CGG-CCG-CTT. The first triplet changes from CCG to CGG, meaning one nucleotide (C→G) is swapped, which is a substitution.
2. Autosomal dominant disorders are caused by mutations in non-sex (autosomal) chromosomes, and the mutation is a gain-of-function (dominant) mutation, as one copy of the mutated allele causes the disease.
3. A single nucleotide swap that changes the codon (and thus the amino acid it codes for) is a missense mutation, which is the type here.

Answer:

1. Marfan syndrome is an autosomal dominant disorder, so the mutation that causes it is a gain-of-function mutation.
2. According to the DNA sequences shown, Marfan syndrome can be caused by a substitution mutation in the FBN1 gene.
3. This mutation is likely a missense mutation.