ATP, or adenine triphosphate, is a nucleotide that is used for energy in many metabolical processes. Plants use ATP, like the lavender in this photo. ATP stores chemical energy in its three phosphate bonds. The last bond is not stable, and when it detaches, energy is released. ATP is made in cellular respiration, which takes place in the mitochondria of animal cells. ATP is also made in photosynthesis in the chloroplasts of plant cells.