How does ATP function as an energy carrier in cells?

ATP functions as an energy carrier in cells by transferring energy from exergonic reactions to endergonic reactions.

ATP, or adenosine triphosphate, is a molecule that stores and transfers energy within cells. It is composed of a nitrogenous base, adenine, a sugar, ribose, and three phosphate groups. The bonds between the phosphate groups are high-energy bonds that can be broken to release energy.

When energy is needed for cellular processes, the ATP molecule donates one of its phosphate groups to another molecule, such as a protein or an enzyme, through a process called phosphorylation. This transfer of the phosphate group releases energy, which can be used to power endergonic reactions, such as muscle contraction or protein synthesis.

After the phosphate group is transferred, the ATP molecule becomes ADP, or adenosine diphosphate, which has only two phosphate groups. The ADP can then be recycled back into ATP through cellular respiration, which involves breaking down glucose and other molecules to release energy and reform ATP.

Overall, ATP functions as an energy carrier in cells by transferring energy from exergonic reactions to endergonic reactions through the transfer of phosphate groups. Its ability to be recycled and reused makes it a crucial molecule for cellular processes.