What is a nucleotide?

A nucleotide is defined as the subunit molecule of a nucleic acid, such as DNA or RNA. Each nucleotide consists of three components: a phosphate group, a five-carbon sugar (either ribose in RNA or deoxyribose in DNA), and a nitrogenous base (which can be adenine, thymine, cytosine, guanine, or uracil). Together, nucleotides link together through phosphodiester bonds to form long chains, creating the backbone of nucleic acids. The sequence of these nucleotide subunits encodes genetic information, making them crucial for the storage and transmission of genetic data within organisms.

Understanding the structure and function of nucleotides highlights their significance in biological processes, particularly in genetics and molecular biology. Other answer choices do not accurately describe a nucleotide; proteins are made of amino acids, carbohydrates are built from simple sugars, and components of cell membranes primarily involve lipids and proteins, indicating that they belong to different biological categories.