Question

One of the following is true with respect to AUG
A. it codes for methionine only
B. it is also an initiation codon
C. it codes for methionine in both prokaryotes and eukaryotes
D. all of the above

Answer 1

Hint: Codons refer to the sequence of DNA or RNA nucleotides that correspond with specific amino acids or stop the signal during protein synthesis and these codons are found in the mRNA (messenger RNA).

Complete answer:
A codon is a triplet i.e. a codon consists of three nitrogen bases that code for one particular amino acid in a polypeptide chain and the relationship between the sequence of amino acids in a polypeptide chain and the nucleotide sequence of DNA or mRNA is known as genetic code or codon. These codons are present on the mRNA and attach with their complementary sequence termed as anticodon which is present on the tRNA during polypeptide synthesis.
Specific codons are present for the initiation of translation (chain initiation codons) and for the termination of translation (chain termination codons) in eukaryotes. Polypeptide chain synthesis is initiated by two initiation codons (the first codon of messenger RNA) are AUG and GUG. AUG codon codes for the methionine whereas GUG also functions as a start codon. These start codons always codes for the methionine and they are universal and codes for the same in both eukaryotes and prokaryotes.
Therefore, AUG:
-it codes for methionine only
-One of the following is true with respect to AUG
-it codes for methionine in both prokaryotes and eukaryotes

Hence, the correct answer is option (D).

Note: Translation is a process by which genetic information is tuned into amino acids and sequence by following the instructions of the genetic code or codons. There are a total of 64 codons that code for 20 amino acids which are present in all organisms.