AUG begins translation and codes methionine; UAA, UAG and UGA end it.
AUG sets the reading frame; in bacteria a Shine-Dalgarno sequence aligns the ribosome, while in eukaryotes the ribosome scans from the cap. Stop codons are recognised by proteins (release factors), not tRNAs.
Readthrough of stop codons can be exploited by some drugs.
AUG begins translation and codes methionine; UAA, UAG and UGA end it.
Start and Stop Codons is one of the 52 topics in Molecular Biology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Initiation, Elongation, Termination, Promoter, Translation.
Selenocysteine is encoded by UGA in special contexts.
Work through the Beginner topics in Molecular Biology first, such as Central Dogma, DNA Replication, Base Pairing, then return to Start and Stop Codons. Intermediate topics assume the Beginner vocabulary.
The closest topics to Start and Stop Codons are Initiation, Elongation, Termination, Promoter, Translation, Codon. Comparing them side by side is a good way to see how the ideas connect.
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Start and Stop Codons. To practise the whole of Molecular Biology, use the Molecular Biology quiz.
Start and Stop Codons: AUG begins translation and codes methionine; UAA, UAG and UGA end it. Initiation, Elongation, Termination: The three stages of translation: assembly at the start codon, chain growth, and release at a stop codon. Read both side by side and note what each one explains.
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Initiation, Elongation, Termination and explain the difference aloud. Finally, take the Molecular Biology quiz and come back to this page for any question you miss.
The three stages of translation: assembly at the start codon, chain growth, and release at a stop codon.
🧫 Molecular BiologyA DNA sequence where RNA polymerase and transcription factors bind to start transcription of a gene.
🧫 Molecular BiologyRibosomes read the mRNA codons to assemble amino acids into a protein.
🧫 Molecular BiologyA triplet of mRNA bases that codes for one amino acid or a stop signal.
🧫 Molecular Biology