Question

Similarity between DNA and RNA is that both have

• A. Similar sugars
• B. Similar mode of replication
• C. Similar pyrimidines
• D. Polymers of nucleotides

Answer 1

The correct option is D Polymers of nucleotides

DNA and RNA are the polymers of nucleotides which are made up of sugar, the nitrogenous base and phosphate moiety which makes option D correct. DNA and RNA both have four bases; two purines and two pyrimidines, in the nucleotide chains. The purines adenine and guanine and the pyrimidine cytosine are common to both DNA and RNA. DNA has the pyrimidine thymine; RNA has the pyrimidine uracil, option C is incorrect. The deoxyribonucleotide units of DNA contain 2’deoxy-D-ribose sugar, and the ribonucleotide units of RNA contain D-ribose sugar; the difference lying in the absence of an oxygen atom at 2’ position, not in a number of carbon atoms. This makes option A wrong. DNA replication is a bidirectional, semi-conservative event which is carried out by primer-dependent DNA polymerase enzyme using the DNA template strand. RNA replication occurs by transcription DNA template; it is carried out in the nucleus by RNA polymerase that adds ribonucleotides to free 3’ hydroxyl group of primer. This makes option B incorrect. The correct answer is D.