Cells use the ATP molecule for energy storage and as a source of energy.
ATP stands for adenosine triphosphate. This molecule is composed of an adenosine molecule bonded to three phosphate groups. If there are only 2 phosphate molecules present, the molecule becomes ADP or adenosine diphosphate. During the process of cellular respiration, the chemical energy stored in the food is released. The cell uses this released energy and the ADP molecule bonds with a third phosphate molecule, thus resulting in a molecule of ATP. The cell uses this ATP molecule as the energy currency. When a molecule of ATP is used for energy for cellular processes, it converts back to ADP and releases the energy stored in the phosphate bond. The ADP molecule can convert back to the ATP molecule when more energy is available from respiration. Thus, a constant cycle is maintained between ADP and ATP molecules.
Mitochondria is the organelle in which ATP is produced and hence is known as the powerhouse of the cell.
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