Substitution mutation is defined as a mutation in which a single base is replaced, potentially altering the gene product. Which option best represents this definition?

Substitution mutation is defined as a mutation in which a single base is replaced, potentially altering the gene product. Which option best represents this definition?

• A. Mutation in which a single base is replaced, potentially altering the gene product
• B. A deletion of a base
• C. An insertion of an extra base
• D. A mutation that moves a chromosome segment

Answer: (A)

The idea being tested is what defines a substitution mutation. A substitution mutation is when one base is replaced by a different base, which can change the codon and potentially alter the protein produced. The option that states this exact scenario matches the definition precisely. The other possibilities describe different changes: deletion removes a base, insertion adds a base, and moving a chromosome segment is a larger chromosomal rearrangement. Substitution mutations affect a single nucleotide and can lead to various outcomes in the gene product, from no change due to codon redundancy to a change in amino acid or introduction of a stop signal.

The idea being tested is what defines a substitution mutation. A substitution mutation is when one base is replaced by a different base, which can change the codon and potentially alter the protein produced. The option that states this exact scenario matches the definition precisely. The other possibilities describe different changes: deletion removes a base, insertion adds a base, and moving a chromosome segment is a larger chromosomal rearrangement. Substitution mutations affect a single nucleotide and can lead to various outcomes in the gene product, from no change due to codon redundancy to a change in amino acid or introduction of a stop signal.