What biomolecule serves as the primary energy currency in cells?

Adenosine triphosphate (ATP) serves as the primary energy currency in cells because it is specifically designed to store and transfer energy for various cellular processes. ATP consists of a ribose sugar, adenine, and three phosphate groups. The high-energy bonds between the phosphate groups are crucial, as they release energy when broken, which can then be harnessed by the cell to perform work, such as muscle contraction, active transport, and biosynthesis.

In contrast, DNA functions primarily as the genetic blueprint of life, storing and transmitting genetic information, while RNA plays roles in coding, decoding, regulation, and expression of genes. Glucose, while it is a fundamental source of energy that gets converted into ATP through cellular respiration, is not utilized directly as an energy currency; it must first be metabolized to form ATP before cells can use that energy effectively. Thus, ATP is unique in its role as the immediate source of energy for cellular activities, making it the correct answer to the question.