Question

RNA code for DNA codon ATG will be
A) ATG
B) AUG
C) UAC
D) TAC

Answer 1

In the organisms where coded genetic information is contained in the DNA molecule, different genetically controlled functions of their cells are performed by a different kind of nucleic acid called non-genetic ribonucleic acid (RNA)

Complete answer:
DNA and RNA have two types of nitrogenous bases (purines and pyrimidines) in the nucleotide chains. The two purines are namely adenine and guanine and three pyrimidines are namely cytosine, thymine and uracil. The purines -adenine and guanine and the pyrimidine -cytosine are common to both DNA and RNA.

DNA has the pyrimidine thymine whereas RNA has the pyrimidine uracil. A purine base pairs with pyrimidine and pyrimidine base pairs with purine as adenine and guanine pair with thymine and cytosine respectively. Since RNA has uracil in place of thymine; adenine pairs with uracil in RNA.

Let us analyse the options and find the correct answer.
Option A: It is not possible to pair with the same nitrogenous bases. Therefore, this is an incorrect answer.
Option B: AUG can't code for DNA codon ATG because adenine and guanine can pair with uracil and cytosine respectively. Therefore, this is an incorrect answer.
Option C: DNA codon ATG will code for RNA codon UAC as the adenine, thymine and guanine can pair with uracil, thymine and cytosine respectively. Therefore, this is the correct answer.
Option D: TAC can't code for DNA codon ATG because adenine can pair with uracil in RNA. Therefore, this is an incorrect answer.

Thus, the correct answer is option (C) UAC.

Note: RNA is synthesized by transcription of DNA template strand, nucleotide sequence of newly formed RNA is complementary to its DNA template strand.