Part B
Think about the DNA coding sequence of a gene. If an A were swapped for a T, what kind of mutation could it cause and why?
a) It could cause a frameshift nonsense or frameshift missense mutation because it would change the reading frame of the codon triplet. b) It could cause a silent, missense, or nonsense mutation because those are the types that can be caused by a nucleotide-pair substitution like this one. c) It could cause a nonsense mutation because the sequence would no longer be the same, so the protein would be shorter and non-functional. d) It could cause a silent mutation because A and T are complementary to each other so it is not really a substitution mutation.
Part C
Why is a frameshift missense mutation more likely to have a severe effect on phenotype than a nucleotide-pair substitution missense mutation in the same protein?
a) A substitution missense mutation causes the protein to be shorter and thus non-functional. b) A frameshift missense will cause the codons to be out of order, but a substitution missense does not change the order of the codons. c) A frameshift missense mutation will cause an early Stop codon, but a substitution missense might be silent. d) A substitution missense affects only one codon, but a frameshift missense affects all codons downstream of the frameshift.
Part D
Which of the following sequences shows a frameshift mutation compared to the wild-type mRNA sequence?
a) wild-type 5â-AUGCAUACAUUGGAGUGA-3â mutant 5â-AUGCAUACAGAGUGA-3â
b) wild-type 5â-AUGCAUACAUUGGAGUGA-3â mutant 5â-AUGCAUACGUUGGAGUGA-3â
c) wild-type 5â-AUGCAUACAUUGGAGUGA-3â mutant 5â-AUGCAUACAUCUGGAGUGA-3â
d) wild-type 5â-AUGCAUACAUUGGAGUGA-3â mutant 5â-AUGCAUGUGACAUUGGAGUGA-3â
Part F
Suppose that the triplet of nucleotides indicated in bold (AGC) spans two codons, that is, CTA and GCC. If the triplet AGC were deleted from this DNA coding sequence, what effect would it have on the resulting protein?
5â-ATGCTAGCCTATCGTAAC-3â
a) The two flanking codons would be altered, but the rest of the amino acid sequence would be the same because there would be no frameshift. b) The entire amino acid sequence would be altered due to the frameshift. c) All of the amino acids after the deletion would be altered due to the frameshift. d) All of the amino acids up to the deletion would be altered due to the frameshift.
Part B
Think about the DNA coding sequence of a gene. If an A were swapped for a T, what kind of mutation could it cause and why?
| a) It could cause a frameshift nonsense or frameshift missense mutation because it would change the reading frame of the codon triplet. | ||||||||||||||||||||||||||||
| b) It could cause a silent, missense, or nonsense mutation because those are the types that can be caused by a nucleotide-pair substitution like this one. | ||||||||||||||||||||||||||||
| c) It could cause a nonsense mutation because the sequence would no longer be the same, so the protein would be shorter and non-functional. | ||||||||||||||||||||||||||||
| d) It could cause a silent mutation because A and T are complementary to each other so it is not really a substitution mutation. Part C Why is a frameshift missense mutation more likely to have a severe effect on phenotype than a nucleotide-pair substitution missense mutation in the same protein?
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