Name a start codon and a stop codon in the standard genetic code.

Name a start codon and a stop codon in the standard genetic code.

• A. Start AUG; Stop UAA, UAG, UGA.
• B. Start UAA; Stop AUG, UAG, UGA.
• C. Start UGA; Stop UAA, UAG, AUG.
• D. Start UAG; Stop UAA, UGA, UGA.

Answer: (A)

Protein synthesis starts when the ribosome finds the start signal on an mRNA. In the standard genetic code, the start codon is AUG, which also codes for the amino acid methionine. This codon sets the reading frame for the entire message. Stop codons signal the end of translation and do not code for amino acids; the three stop codons are UAA, UAG, and UGA. When the ribosome encounters any of these, release factors are recruited and the newly made polypeptide is released, completing synthesis. Note that AUG is the canonical start codon in most contexts, though some organisms can use alternative starts in certain situations.

Protein synthesis starts when the ribosome finds the start signal on an mRNA. In the standard genetic code, the start codon is AUG, which also codes for the amino acid methionine. This codon sets the reading frame for the entire message. Stop codons signal the end of translation and do not code for amino acids; the three stop codons are UAA, UAG, and UGA. When the ribosome encounters any of these, release factors are recruited and the newly made polypeptide is released, completing synthesis. Note that AUG is the canonical start codon in most contexts, though some organisms can use alternative starts in certain situations.