A nucleoside differs from a nucleotide. It lacks the:

Correct Answer: Option 3

Concept:

• Nucleic acids are complex organic molecules with high molecular weights.
• Found in every living cell, nucleic acids play an important role in hereditary.
• There are two types: DNA and RNA.

Explanation:

Deoxyribonucleic acid (DNA):

• DNA is the genetic material found in nature along with RNA.
• A DNA molecule is made up of several nucleotides.
• Each nucleotide is made up of 3 parts:
  • A phosphate group
  • A pentose sugar - Deoxyribose in DNA and Ribose in RNA
  • A nitrogenous base.
• A nitrogenous base is linked to the OH of 1' carbon atom of pentose sugar. It is linked through N-glycosidic linkage.
• The structure so formed consisting of a nitrogenous base and a pentose sugar is called nucleoside.
• When a phosphate group gets linked to OH of 5' carbon atom of a nucleoside through the phosphodiester linkage, a nucleotide is formed.

Thus from the above-given information, nucleoside consists of a nitrogenous base and a pentose sugar. It lacks the phosphate group.

So the correct answer is option 3.