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Insertion of two extra bases in the middle of a structural gene most likely produces:
A{'text': 'A silent mutation', 'label': 'A'}
B{'text': 'A single amino acid substitution at the site', 'label': 'B'}
C{'text': 'A premature stop only if a stop codon is inserted', 'label': 'C'}
D{'text': 'A frameshift altering all downstream codons', 'label': 'D'}
Answer & Solution
Correct answer: D. {'text': 'A frameshift altering all downstream codons', 'label': 'D'}
Inserting one or two bases shifts the reading frame from the insertion onward, scrambling every codon downstream. Three (or multiples of three) bases preserve the frame, adding or removing whole codons.
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