Nonsense mutation

Definition

A nonsense mutation is a point mutation in a DNA sequence that results in a premature stop codon, leading to the truncation of the resultant protein. This often renders the protein nonfunctional.

5 Must Know Facts For Your Next Test

1. Nonsense mutations lead to the introduction of a stop codon earlier than expected in the mRNA sequence.
2. These mutations can result in incomplete and usually nonfunctional proteins.
3. They are one type of point mutation, specifically involving a single nucleotide change.
4. Nonsense mutations can have severe effects on an organism if they occur in critical genes necessary for survival or function.
5. The three stop codons that can be introduced by nonsense mutations are UAA, UAG, and UGA.

Review Questions

• What is the primary consequence of a nonsense mutation on protein synthesis?
• Which stop codons can be introduced by nonsense mutations?
• How does a nonsense mutation differ from other types of point mutations?

Related terms

Missense Mutation:

A point mutation in which a single nucleotide change results in a different amino acid being incorporated into the protein.

Silent Mutation:

A point mutation that changes a nucleotide without altering the amino acid sequence of the resultant protein.

Frameshift Mutation:

A genetic mutation caused by insertions or deletions of nucleotides that shift the reading frame of the genetic message.