Question

What is a terminator codon? Write two examples.

Hint:

Recall the three stop codons that carry no amino acid and end translation.

Answer 1

Understanding the Question:
A terminator (stop) codon is a triplet of mRNA bases that does not code for any amino acid but instead signals the ribosome to end translation.

Detailed Explanation:
During protein synthesis, the ribosome reads the mRNA codon by codon, adding one amino acid for each codon using the matching tRNA.
When the ribosome reaches a stop codon, no tRNA has an anticodon that matches it, so instead a release factor binds there and causes the completed polypeptide chain to be released from the ribosome.
There are three stop codons in the genetic code, UAA, UAG and UGA, and any one of them marks the end of the coding sequence for a protein.

Final Answer:
A terminator codon stops protein synthesis by having no corresponding tRNA. Examples are UAA and UAG (a third, UGA, also exists). \[ \boxed{\text{UAA, UAG}} \]