What is the primary molecule involved in energy transfer in cells?

The primary molecule involved in energy transfer within cells is adenosine triphosphate, commonly known as ATP. This molecule serves as the main energy currency of the cell, capable of storing and transferring energy through its high-energy phosphate bonds. When ATP is hydrolyzed, it releases energy that can be harnessed for various cellular functions including metabolism, muscle contraction, and active transport across membranes.

ATP is synthesized during cellular respiration processes such as glycolysis, the Krebs cycle, and oxidative phosphorylation, which allows for efficient energy production. While glucose is a vital substrate that can be broken down to ultimately produce ATP, it is not the direct molecule that facilitates energy transfer. Similarly, NADH and FADH2 are electron carriers that play crucial roles in cellular respiration and contribute to ATP production but are not primarily responsible for energy transfer by themselves. Instead, they help drive the production of ATP by donating electrons to the electron transport chain. Hence, ATP stands out as the key molecule in the direct transfer and utilization of energy in cellular processes.