Which of the following codon changes represents a silent mutation?

Rationale

CUC to CUG represents a silent mutation.

A silent mutation occurs when a change in the DNA sequence does not alter the resulting amino acid due to the redundancy in the genetic code. Both CUC and CUG code for the same amino acid, leucine, making this mutation silent as it does not affect the protein product.

A (GAA to GGU) YOUR ANSWER

This change results in a substitution of amino acids; GAA codes for glutamic acid, while GGU codes for glycine. Since these are different amino acids, this mutation would not be classified as silent, as it alters the protein structure and function.

B (AGA to AGU) YOUR ANSWER

AGA codes for arginine, and AGU codes for serine. This mutation leads to a different amino acid being incorporated into the protein, which can significantly affect the protein's properties and function, thus disqualifying it as a silent mutation.

C (CUC to CUG) CORRECT

Both CUC and CUG code for the same amino acid, leucine. This means that despite the change in the nucleotide sequence, the protein remains unchanged as it still incorporates leucine, making this a classic example of a silent mutation.

D (UUA to UUU) YOUR ANSWER

UUA codes for leucine, while UUU codes for phenylalanine. This mutation results in a change from one amino acid to another, thereby affecting the protein's structure and function, and is not a silent mutation.

Conclusion

Silent mutations are characterized by changes in the nucleotide sequence that do not result in alterations to the amino acid sequence of a protein. The mutation from CUC to CUG is an example of this phenomenon, as it preserves the identity of the amino acid (leucine) despite the codon change. In contrast, the other options lead to amino acid substitutions, thus affecting the protein's characteristics and functionality.

Which of the following codon changes represents a silent mutation?

CUC to CUG represents a silent mutation.

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