Question

Match the following.

(I) AUG	(A) Stop codon
(II) AGU	(B) Serine
(III) UGA	(C) Initiation codon

• A. (I)-(A), (II)-(B), (III)-(C)
• B. (I)-(C), (II)-(A), (III)-(B)
• C. (I)-(C), (II)-(B), (III)-(A)
• D. (I)-(B), (II)-(A), (III)-(C)

Answer 1

The correct option is C (I)-(C), (II)-(B), (III)-(A)

Codon refers to a set of three nucleotides present on mRNA which may or may not code for an amino acid upon translation. A nucleotide is made up of a pentose sugar (ribose in case of RNA), phosphate group and nitrogen base. In a polynucleotide chain (that forms the nucleic acid), the sugar and phosphate remain the same, only the nitrogenous bases change. So, a codon is often referred to by the set of nitrogen bases. In RNA, the bases are A, U, G, C.
UAA (ochre), UAG (amber) and UGA (opal) do not specify any amino acid so they are called termination codons or stop codons.
AUG codes for methionine and is initiation or start codon which starts the synthesis of
polypeptide.
AGU codes for serine.