Apentix/AP Biology/Unit 6: Gene Expression and Regulation/Question
AP Biologyeasymcq1 pt

A gene acquires an insertion of two nucleotides within its coding region, well before the normal stop codon. What is the most likely result?

A.Translation proceeds normally because the inserted bases are skipped between codons
B.Splicing deletes the inserted bases before the mRNA leaves the nucleus
C.Exactly two amino acids change and the remainder of the protein is unaffected
D.Codons downstream regroup into a new frame, likely introducing an early stop and a nonfunctional protein

Explanation

Core Concept

Ribosomes partition mRNA into consecutive triplets starting at AUG. Adding two bases slides the grouping for every subsequent codon, replacing nearly the entire downstream amino acid sequence. The scrambled frame commonly reveals a premature stop codon, cutting the product short.

Correct Answer

DCodons downstream regroup into a new frame, likely introducing an early stop and a nonfunctional protein

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