Question

Describe the structure of a nucleotide.

Short answer

A nucleotide is made up of three components: a phosphate group, a 5-carbon sugar (either deoxyribose or ribose), and a nitrogenous base (adenine, guanine, cytosine, thymine in DNA, or uracil in RNA). The structure of a nucleotide allows it to form the double helix structure of DNA or the single strand of RNA by pairing with complementary bases.

Step-by-step solution

Identify the Main Components of a Nucleotide

A nucleotide consists of three main components: a phosphate group, a 5-carbon sugar, and a nitrogenous base.

Understand the Phosphate Group

The phosphate group is a molecule in the nucleotide that contains one phosphorus atom bonded to four oxygen atoms. It is attached to the 5-carbon of the sugar molecule.

Understand the 5-Carbon Sugar

The sugar in the nucleotide is a 5-carbon sugar. These sugars are either deoxyribose, which is found in DNA, or ribose, which is found in RNA. The phosphate group is attached to the 5th carbon of the sugar, and the nitrogenous base is attached to the 1st carbon.

Understand the Nitrogenous Base

The nitrogenous base can be one of five types: adenine, guanine, cytosine, thymine, or uracil. Thymine is only found in DNA while uracil is only found in RNA. Adenine and guanine are classified as purines, and cytosine, thymine, and uracil are pyrimidines. The nitrogenous base connects to the 1st carbon of the sugar molecule.

Visualize the Structure

In the molecular structure of a nucleotide, the phosphate groups and nitrogenous bases form the outer side of the double helix structure in DNA, while the sugars form the backbone on the inside. The nucleotides pair up in a specific manner with the nitrogenous bases forming weak hydrogen bonds with their complementary bases.