Question

Nucleotides are monomers of DNA. What does each nucleotide consist of?
a. A nitrogenous base and a pentose sugar
b. A nitrogenous base and a phosphate group
c. A pentose sugar and a phosphate group
d. A nitrogenous base, a pentose sugar and a phosphate group

Answer 1

Hint: DNA is known to be the genetic material of a wide range of organisms from viruses to humans. They help in the proper development, functioning as well as growth and reproduction of these organisms.

Complete answer:
The DNA molecule is known to comprise two polynucleotide chains that coil around each other giving rise to the double helical structure. The polynucleotides are in turn made up of mono nucleotides which are made up of four different types of nitrogenous bases namely- guanine, cytosine, thymine and adenine. Apart from them the nucleotide DNA is known to comprise a phosphate group and a pentose sugar known as the deoxyribose sugar. The nucleotides are joined to each other by means of covalent bonds between the phosphate of one and the sugar residue of the other leading to the formation of the sugar phosphate backbone that are characteristic of the DNA molecule. Base pairing also exists between the nitrogenous bases where the adenine and thymine bases are joined by two hydrogen bonds and the cytosine and guanine bases are joined by three hydrogen bonds. The DNA structure is stabilized by the help of positively charged magnesium ions that helps to shield the negative charge of the phosphorus backbone.

Hence the correct answer is option (d).

Note: Both of the polynucleotide strands of the DNA are known to comprise biological information. Out of the two strands that code for essential proteins is known as the coding strand and the opposite strand is known as the non-coding strand.