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
True about genetic code 
Select and explain. 
A. AUA codes for methionine in mitochondria, B. UGA codes for selenocysteine, C. AUG codes for initiator codon in mammalian cell, D. AGA & AGG act as chain terminator in mammalian
A: AUA codes for methionine in mitochondria
Answer: A: AUA codes for methionine in mitochondria 
Explanation: UGA is a stop codon, but in special circumstance, it stands for seleno-cysteine the codon AUG both codes for methionine and serves as an initiation site: the first AUG in a mRNA&;s coding region is where translation into protein begins.Ref: DM Vasudevan, 7th edition, page no: 599