Stop codons

Definition

Stop codons are nucleotide triplets within messenger RNA (mRNA) that signal the end of protein synthesis. They do not code for any amino acid and hence terminate translation.

5 Must Know Facts For Your Next Test

1. The three stop codons are UAA, UAG, and UGA.
2. Stop codons are also referred to as termination codons.
3. During translation, stop codons prompt the release factors to bind to the ribosome.
4. Stop codons ensure that proteins are synthesized correctly by signaling the end of the polypeptide chain.
5. Mutations in stop codons can cause diseases by producing incomplete or nonfunctional proteins.

Review Questions

• What is the main function of a stop codon during translation?
• Name all three stop codons found in mRNA.
• What happens when a ribosome encounters a stop codon during protein synthesis?

Related terms

mRNA:

Messenger RNA is a type of RNA that carries genetic information from DNA to the ribosome.

Translation: Translation is the process where ribosomes synthesize proteins using mRNA as a template.

Release Factors: Release factors are proteins that recognize stop codons and help terminate translation by releasing the newly made polypeptide from the ribosome.