Stop codon

Definition

A stop codon is a nucleotide triplet within mRNA that signals the termination of translation. It instructs the ribosome to release the newly synthesized polypeptide chain.

5 Must Know Facts For Your Next Test

1. There are three stop codons: UAA, UAG, and UGA.
2. Stop codons do not code for any amino acids.
3. They signal the end of protein synthesis during translation.
4. Mutations that create premature stop codons can lead to truncated and often nonfunctional proteins.
5. Release factors recognize stop codons and promote the disassembly of the translation machinery.

Review Questions

• What are the three nucleotide sequences that function as stop codons?
• How do stop codons affect protein synthesis?
• What role do release factors play in relation to stop codons?

Related terms

Start Codon: The nucleotide triplet (AUG) that signals the initiation of translation.

mRNA: Messenger RNA that carries genetic information from DNA to the ribosome.

Ribosome: The molecular machine that facilitates protein synthesis by translating mRNA into polypeptides.