Which sequence is a stop codon?

Which sequence is a stop codon?

• A. UAA
• B. AUG
• C. GCU
• D. UUU

Answer: (A)

Stop codons signal the end of translation during protein synthesis. In RNA, codons are read in groups of three, and most specify an amino acid, but stop codons tell the ribosome to terminate and release the completed protein. The stop signals are UAA, UAG, and UGA. When the sequence is UAA, no amino acid is added; instead, the ribosome stops and the protein is released. AUG, by contrast, is the start codon that codes for methionine and begins translation. GCU codes for alanine, and UUU codes for phenylalanine. So, among the options, UAA is the stop codon.

Stop codons signal the end of translation during protein synthesis. In RNA, codons are read in groups of three, and most specify an amino acid, but stop codons tell the ribosome to terminate and release the completed protein. The stop signals are UAA, UAG, and UGA. When the sequence is UAA, no amino acid is added; instead, the ribosome stops and the protein is released. AUG, by contrast, is the start codon that codes for methionine and begins translation. GCU codes for alanine, and UUU codes for phenylalanine. So, among the options, UAA is the stop codon.