alleryInsertion of two extra bases in the middle of a structural gene most likely produces:
AA silent mutation
BA single amino acid substitution at the site
CA premature stop only if a stop codon is inserted
DA frameshift altering all downstream codons
Answer & Solution
Correct answer: D. A frameshift altering all downstream codons
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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