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Difficulty: MediumGene Mutations and Chromosomal Aberrations

An insertion or deletion of a single nucleotide base within the coding region of a gene alters the reading frame, changing all subsequent triplet codons during protein synthesis.

Answer: Answer

Answer

The statement is true. Inserting or deleting a single nucleotide base shifts the triplet reading frame during translation, altering every codon following the mutation site.
The statement is correct because adding or removing one nucleotide alters the three-by-three reading frame of codons during protein synthesis, causing a frameshift mutation that alters all downstream amino acids.

Step-by-Step Solution

1
Examine the nature of the genetic code during translation.
Messenger RNA is read by ribosomes in consecutive, non-overlapping triplets called codons.
Each codon specifies a particular amino acid in the synthesizing polypeptide chain.
2
Analyze the impact of inserting or deleting a single nitrogenous base.
Altering the base count by one shifts the triplet alignment down the entire remaining length of the gene.
Because the ribosome continues reading in groups of three, the reading frame boundary changes at the mutation point.
3
Evaluate the outcome on the protein product.
All downstream codons code for different amino acids, or introduce an early stop codon (nonsense mutation).
This frameshift effect changes the entire primary structure of the protein from that point forward.

Key Concept

Frameshift Mutation Mechanism
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Topics

Gene Mutations and Chromosomal Aberrations

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