What is the primary energy molecule for cells?

ATP, or adenosine triphosphate, is the primary energy molecule for cells because it serves as a central energy currency in biological systems. ATP stores and transports chemical energy within cells, enabling various biochemical processes necessary for life.

When ATP is hydrolyzed, it releases energy that can be utilized for processes such as muscle contraction, active transport across membranes, and biosynthetic reactions. The high-energy phosphate bonds between the phosphate groups facilitate this energy release, making ATP uniquely suited for powering cellular activities.

While ADP (adenosine diphosphate), FADH2, and NADH are important molecules in metabolic pathways, they do not function as the direct energy currency in the way ATP does. ADP can be converted back to ATP in cellular respiration, but it does not provide energy itself. FADH2 and NADH are involved in electron transport and energy production processes, but they act more as electron carriers than as direct energy sources for cellular functions. Thus, ATP stands out as the key molecule that cells rely on for immediate energy needs.