This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of nucleic acids, Subject name: Biochemistry
Stop codon 
Select and explain. 
A. UAG, B. UCA, C. UAC, D. AUG
A: UAG
Answer: A: UAG 
Explanation: They do not code for any amino acid Mark the end of protein synthesisOther stop codons are UAA UGARef: DM Vasudevan, 7th edition, page no: 599