Question

What is the difference between a nucleoside and a nucleotide?

Short answer

Answer: The main difference between nucleosides and nucleotides is that nucleosides consist of a nitrogenous base and a sugar molecule, while nucleotides contain an additional one or more phosphate groups attached to the sugar molecule.

Step-by-step solution

Define a nucleoside

A nucleoside is an organic molecule that consists of a nitrogenous base bonded to a sugar molecule. The nitrogenous base can be a purine or a pyrimidine, while the sugar molecule can be a ribose (in RNA) or deoxyribose (in DNA).

Define a nucleotide

A nucleotide is an organic molecule that consists of a nucleoside and one or more phosphate groups. The nucleoside is composed of a nitrogenous base and a sugar molecule, and the phosphate groups are attached to the sugar molecule. Nucleotides are the basic building blocks of nucleic acids like DNA and RNA.

Compare components

The primary difference between nucleosides and nucleotides lies in their components. Both molecules have a nitrogenous base and a sugar molecule in common, which together form a nucleoside. However, a nucleotide also includes one or more phosphate groups that are attached to the sugar molecule.

Explain their roles

Nucleosides can be considered as the structural subunits of nucleotides. Nucleotides, on the other hand, serve as the monomers for the formation of nucleic acids like DNA and RNA, which are crucial for storing and transmitting genetic information in cells. Nucleotides also have essential roles in cellular metabolism and signaling, like serving as energy molecules (e.g., ATP) and secondary messengers (e.g., cAMP).

Summarize the difference

To summarize, the main difference between nucleosides and nucleotides is that nucleosides consist of a nitrogenous base and a sugar molecule, while nucleotides contain an additional one or more phosphate groups attached to the sugar molecule. Nucleosides serve as structural subunits of nucleotides, which play critical roles in the formation of nucleic acids, cell metabolism, and signaling.