What is the start codon used to initiate translation in mRNA?

What is the start codon used to initiate translation in mRNA?

• A. UAA
• B. AUG
• C. UAG
• D. UGA

Answer: (B)

The starting signal for translating the genetic message is a specific codon that tells the ribosome where to begin and which amino acid to incorporate first. This codon is AUG. It not only marks the reading frame for the rest of the message but also codes for the amino acid methionine, which is used as the first amino acid in most proteins. In bacteria, the initial methionine can be formylated, but the start codon itself remains AUG. The other codons listed—UAA, UAG, and UGA—are stop codons. They signal the end of the protein-coding sequence and cause translation to terminate, releasing the completed polypeptide. So AUG is the start signal that initiates translation and introduces methionine, while the others stop the process.

The starting signal for translating the genetic message is a specific codon that tells the ribosome where to begin and which amino acid to incorporate first. This codon is AUG. It not only marks the reading frame for the rest of the message but also codes for the amino acid methionine, which is used as the first amino acid in most proteins. In bacteria, the initial methionine can be formylated, but the start codon itself remains AUG.

The other codons listed—UAA, UAG, and UGA—are stop codons. They signal the end of the protein-coding sequence and cause translation to terminate, releasing the completed polypeptide. So AUG is the start signal that initiates translation and introduces methionine, while the others stop the process.