Question

Which one of the following is start codon?
A) AUG
B) UGA
C) UAA
D) UAG

Answer 1

Hint:The ribosome always reads the mRNA in 3 continuous nucleotide codons, which starts with the start codon, which is AUG, it codes for amino acid methionine. The order of the bases inside the codons are responsible for determining the type of amino acid which might be introduced to the developing protein chain via way of means of the ribosome.

Complete answer:
Codons are the nucleotide base triplets that specify a particular amino acid in proteins.The start codon is responsible for specifying the primary codon in the mRNA transcript which is translated. It codes for methionine in eukaryotes and a changed Met in prokaryotes. "AUG '' is the most widely used start codon, on tRNA the anticodon for this is UAC. UAA, UAG and UGA are the stop codons.
Thus, the correct solution is option (A) AUG.
Additional points:
In DNA the start codon initiates the translation of the first amino acid in the polypeptide chain. GUG is an effective initiation codon or start codon and codes for Valine. AUG is the start codon in 83% of the times and GUG 14% of the times.

Thus, the correct answer is option (D).

Note:AUG is the start codon of mRNA which codes for amino acid methionine in eukaryotes and changes fMet. fMet is formylmethionine which codes for AUG in case of prokaryotes. It is the primary codon at which the interpretation of proteins begins, tRNA with anticodon UAC.