Because it can be fully charged by an addition of a phosphate group.
ADP is like a partially charged battery that will produce a dim light & ATP is like a fully charged battery that produces a bright light
how is a molecule of ADP like a rechargeable battery
ADP is like a partially charged battery because there is still energy contained within the bond between the first and second phosphate groups. However, it lacks the "high energy" bond that exists between the second and third phosphate groups in ATP.
ATP is like a charged battery
Because ATP stores energy and releases it turning into ADP in the process. This ADP is then converted back to ATP by the cells so that its energy is ready when required, just like a rechargeable battery.
adp
adp+p(i)--->atp ADP +P ---> ATP
ATP (with 3 Phosphate Groups) would be the full charged battery. ADP (with 2 Phosphate Groups) would be the partially charged battery. To release energy, the bond between the 2nd and 3rd phosphate group is released. To store energy, a bond is made between the 2nd and 3rd phosphate group.
ATP (with 3 Phosphate Groups) would be the full charged battery. ADP (with 2 Phosphate Groups) would be the partially charged battery. To release energy, the bond between the 2nd and 3rd phosphate group is released. To store energy, a bond is made between the 2nd and 3rd phosphate group.
When ATP is used, it becomes ADP or Adenine Di-Phosphate. Adding another phosphate will "recharge" ATP.
The terminal phosphate group is broken off. The negative charge on the phosphate groups make them willing to separate.
ATP has much more energy than ADP because it has one more phosphate bond which contains energy.