key term - Silent mutation

Definition

A silent mutation is a change in the DNA sequence that does not alter the amino acid sequence of the resulting protein. These mutations typically occur in the coding region of a gene but do not affect the protein's functionality. Silent mutations highlight the redundancy in the genetic code, where multiple codons can encode the same amino acid without any change in the protein's structure or function.

5 Must Know Facts For Your Next Test

1. Silent mutations can occur due to a change in one nucleotide base pair, yet they do not impact the final protein product due to the redundancy of the genetic code.
2. Even though silent mutations do not change the amino acid sequence, they can potentially affect gene expression levels or mRNA stability.
3. These mutations are often identified through sequencing technologies and can be used as markers in population genetics studies.
4. In some cases, silent mutations may influence splicing signals in pre-mRNA, potentially leading to changes in the processed mRNA.
5. The presence of silent mutations can have evolutionary implications, as they may serve as reservoirs of genetic variation without immediately affecting phenotype.

Review Questions

• How do silent mutations illustrate the redundancy of the genetic code?
  • Silent mutations demonstrate the redundancy of the genetic code because they involve changes in the DNA sequence that do not result in a different amino acid being produced. This is possible because multiple codons can correspond to the same amino acid. For instance, a change from one codon to another that codes for the same amino acid shows that even with a mutation, the protein remains unchanged.
• Discuss how silent mutations might influence gene expression or mRNA stability despite not changing the amino acid sequence.
  • Although silent mutations do not alter the amino acid sequence of proteins, they can still affect gene expression and mRNA stability. For example, changes in codon usage may influence how efficiently mRNA is translated into protein. Additionally, if a silent mutation occurs at or near splicing sites or regulatory elements, it could impact how the gene is expressed by altering mRNA processing or stability.
• Evaluate the potential evolutionary advantages or disadvantages of silent mutations within populations over time.
  • Silent mutations provide evolutionary advantages by allowing genetic variation to accumulate without immediate phenotypic consequences. This hidden diversity can be advantageous during environmental changes, as it allows for rapid adaptation if beneficial mutations arise from previously neutral ones. However, if silent mutations disrupt regulatory sequences or splicing, they could create disadvantages. Overall, while silent mutations might seem harmless, their effects on gene expression and potential to contribute to evolutionary processes make them significant in understanding genetic diversity.

Related terms

Codon: A sequence of three nucleotides in mRNA that specifies a particular amino acid or a stop signal during protein synthesis.

Point mutation: A type of mutation where a single nucleotide change results in the alteration of a codon, which can be silent, missense, or nonsense.

Genetic code: The set of rules by which information encoded in genetic material is translated into proteins by living cells.