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Biochemistry Molecular Genetics 9b5a262d

Which of the following types of mutations generally leads to a truncated protein?

A
Deletion
B
Frameshift mutation
C
Insertion
D
Missense mutation
High-Yield Explanation
Ans. B. Frameshift mutationa. Although each type of mutation can cause protein truncation, a frameshift mutation usually introduces a stop codon very shortly after the frameshift. In coding sequences, there are three possible reading frames that can be translated, only one of which leads to synthesis of the correct protein.b. The other two reading frames generally have numerous stop codons throughout, whereas the correct reading frame only has a stop codon at the very end. Small deletions and insertions will generally not affect protein size if the insertion or deletion is a multiple of three bases (one codon).c. These types of insertions or deletions maintain the same reading frame during translation. Missense mutations are alterations in a single codon such that the three base triplet encodes for a different amino acid. Silent mutations are alterations in a single codon such that the new codon still encodes for the same amino acid. This is possible because of the degeneracy of the genetic code.

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