Q.Which of the following is NOT present in DNA?

Both DNA and RNA are polymers of nucleotides joined by phosphodiester linkages -- the 3'-OH of one nucleotide's sugar bonded to the 5'-phosphate of the next -- building an alternating sugar-phosphate (P-S-P-S) backbone common to both nucleic acids, with one free phosphate at the chain's 5' end and one free -OH at its 3' end. A nucleic acid's primary structure (its base sequence, read from the 5' end) is what actually carries genetic information, since the backbone itself is identical throughout. DNA specifically forms a double helix (Watson and Crick, 1953): two antiparallel polynucleotide strands wound right-handed around a common axis, sugar-phosphate backbones outside and bases inside, held together by strict complementary hydrogen-bonded base pairing -- adenine to thymine (2 H-bonds) and guanine to cytosine (3 H-b …