What is the function of the phosphate group in a nucleotide?

The function of the phosphate group in a nucleotide is integral to the structure of nucleic acids, such as DNA and RNA. The phosphate group forms the backbone of these molecules.

In a nucleotide, which consists of a phosphate group, a sugar molecule (deoxyribose in DNA, ribose in RNA), and a nitrogenous base, the phosphate group connects to the sugar of one nucleotide and links to the sugar of another nucleotide. This results in a long chain structure where the phosphate groups alternate with sugar molecules, creating a stable backbone that supports the nitrogenous bases. This arrangement allows the bases to project outward, where they can interact for base pairing, which is crucial for the integrity and function of genetic material.

Understanding this role helps clarify why the backbone formed by phosphate and sugar is essential for the overall structure and stability of nucleic acids. Thus, the correct choice highlights an important aspect of molecular biology principles concerning DNA and RNA.