What is the energy-transferring molecule used by cells?

The energy-transferring molecule commonly used by cells is ATP, or adenosine triphosphate. ATP serves as the primary energy currency within the cell, allowing for the storage and transfer of energy necessary for various biological processes. When ATP is hydrolyzed (broken down) to ADP (adenosine diphosphate) and inorganic phosphate, energy is released. This energy is then utilized in various cellular activities, including muscle contraction, active transport across membranes, and biochemical reactions.

Glucose, while an essential source of energy for cellular respiration and metabolism, must first be broken down through glycolysis and subsequent stages to be converted into ATP. NADPH and FADH2 are also important in metabolic processes but primarily function as electron carriers in biochemical reactions, such as those in cellular respiration and photosynthesis, rather than directly transferring energy for immediate cellular processes like ATP does. Thus, ATP is the molecule that directly supplies energy to power cell functions.