Biology / Unit 6 Bio 1257 short lesson, about 20 seconds
Start and Stop Codons
Captions available
The idea
The start codon AUG sets an mRNA's reading frame and specifies methionine; three stop codons, UAA, UAG, and UGA, end translation without specifying any amino acid.
In practice
A ribosome begins reading at AUG and continues, codon by codon, until it reaches UAA, UAG, or UGA.
Where people slip
A stop codon has no matching tRNA — that absence, not a special pairing event, ends translation.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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