Question

A nucleotide of DNA may contain ________.

a. ribose, uracil, and a phosphate group

b. deoxyribose, uracil, and a phosphate group

c. deoxyribose, thymine, and a phosphate group

d. ribose, thymine, and a phosphate group

Short answer

A nucleotide of DNA may contain deoxyribose, thymine, and a phosphate group.

Step-by-step solution

Introduction

Nucleotides are the building blocks of nucleic acids - deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Nucleotides consist of three parts: a nitrogenous base, a pentose sugar, and a phosphate group. The pentose sugar in a DNA molecule is deoxyribose and in an RNA molecule is ribose. The nitrogenous bases in a DNA molecule can be adenine, guanine, cytosine, or thymine. In an RNA molecule, all the bases are the same except for thymine which is replaced by uracil. The sugar-phosphate backbone of both DNA and RNA is formed by covalent bonds between the phosphate group of one nucleotide and the pentose sugar of the next nucleotide.

Explanation

DNA nucleotides consist of deoxyribose sugar, nitrogenous bases adenine, guanine, cytosine, or thymine, and a phosphate group. Therefore, ribose, uracil, and a phosphate group does not represent a DNA nucleotide. Hence, option a is incorrect.

DNA nucleotides consist of nitrogenous bases adenine, guanine, cytosine, or thymine. Uracil is the nitrogenous base of an RNA nucleotide. Therefore, deoxyribose, uracil, and a phosphate group cannot be DNA nucleotides. Hence, option b is incorrect.

DNA nucleotides do not contain ribose sugar. Hence, ribose, thymine, and a phosphate group cannot represent a DNA nucleotide. Hence, option d is incorrect.

DNA nucleotides comprise a deoxyribose sugar, any one of the nitrogenous bases - adenine, guanine, cytosine, or thymine and a phosphate group. Therefore, deoxyribose, thymine, and a phosphate group represent a DNA nucleotide. Hence, option c is correct.