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Number of types of nucleotides formed by the nitrogen bases which are common in both types of nucleic acids.
A. 3
B. 8
C. 6
D. 4

Last updated date: 17th Jun 2024
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Hint: Nucleotides are organic molecules consisting of a nucleoside and a phosphate.
They serve as monomeric units of the nucleic acid polymers deoxyribonucleic acid and ribonucleic acid, both of which are essential biomolecules within all life-forms on Earth. The main biological function of a nitrogenous base is to bond nucleic acids together.

Complete answer: All nucleotides have a common structure: a phosphate group linked by a phosphodiester bond to a pentose (a five-carbon sugar molecule) that in turn is linked to an organic base. The two kinds of nucleic acids are – deoxyribonucleic acid and ribonucleic acid. In RNA, the pentose is ribose; in DNA, it is deoxyribose. The two strands are held together by hydrogen bonds between the bases, with adenine forming a base pair with thymine, and cytosine forming a base pair with guanine. A nitrogenous base, or nitrogen-containing base, is an organic molecule with a nitrogen atom that has the chemical properties of a base. The bases adenine, guanine, and cytosine are found in both DNA and RNA. Thymine is found only in DNA, and uracil is found only in RNA.
Hence, the correct answer is option A.

Note: Adenine (A) and guanine (G) are double-ringed purines, and cytosine (C) and thymine (T) are smaller single-ringed pyrimidines. Uracil pairs with adenine through hydrogen bonding. When base pairing with adenine, uracil acts as both a hydrogen bond acceptor and a hydrogen bond donor. In RNA, uracil binds with a ribose sugar to form the ribonucleoside uridine.