What is a stop codon and give examples?

What is a stop codon and give examples?

• A. A codon that starts translation.
• B. A codon that codes for the amino acid methionine.
• C. A signal to terminate translation; examples UAA, UAG, UGA.
• D. A nucleotide that pairs with tRNA anticodons.

Answer: (C)

Stop codons are the signals in mRNA that tell the ribosome to stop translating. They do not code for any amino acid. When the ribosome encounters one of these triplets—UAA, UAG, or UGA—it triggers termination of translation, releasing the newly made polypeptide. This is why the choice describing a signal to terminate translation with those exact examples is correct. For context, a start codon (like AUG) begins translation and codes for methionine; stop codons do not code for amino acids. Also, codons on mRNA pair with tRNA anticodons in three-nucleotide units, not by a single nucleotide, and stop codons are not matched by a tRNA.

Stop codons are the signals in mRNA that tell the ribosome to stop translating. They do not code for any amino acid. When the ribosome encounters one of these triplets—UAA, UAG, or UGA—it triggers termination of translation, releasing the newly made polypeptide. This is why the choice describing a signal to terminate translation with those exact examples is correct. For context, a start codon (like AUG) begins translation and codes for methionine; stop codons do not code for amino acids. Also, codons on mRNA pair with tRNA anticodons in three-nucleotide units, not by a single nucleotide, and stop codons are not matched by a tRNA.