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ATP: BATTERIES IN YOUR BODY?
Adenosine Triphosphate (ATP)
Energy comes in many forms, including light, heat and electricity. Energy can
also be stored in the bonds of chemical compounds. The main compound that cells use to
store and release energy is adenosine triphosphate (uh-DEN-uh-seen try-FAHS-fayt), or
ATP for short. One molecule of ATP consists of a base called adenine, a sugar called
ribose, and three phosphate groups. A diagram of an ATP molecule is in the box below:
Ribose Sugar
Adenine Base
Phosphate Groups
In a way, ATP is like a fully charged battery. Energy is stored in the bond between the
second and third phosphate groups. When this high energy bond is broken, energy is
released and used by the cell for various activities.
CHECKPOINT
 Why do you think ATP is called adenosine TRIphosphate?
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 Where is the high energy bond of an ATP molecule located?
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 Circle this high energy bond in the diagram above.
Adenosine Diphosphate (ADP)
When the high energy bond between the between the second and third phosphate
groups of an ATP molecule are broken, energy is released and used by the cell for
various activities. The breaking of this high energy bond results in the formation of a
new molecule: adenosine diphosphate (uh-DEN-uh-seen die-FAHS-fayt), or ADP for
short. One molecule of ADP also consists of a base called adenine, a sugar called ribose,
but only has two phosphate groups. A diagram of an ADP molecule is in the box below:
Ribose Sugar
Adenine Base
Phosphate Groups
In a way, ADP is like a partially charged battery because energy has been released for
cellular activities. When more energy becomes available, for example, when you eat
food, a phosphate group is added to ADP, again forming a fully charged ATP molecule.
This cycle is constantly occurring in your body!
CHECKPOINT
 Why do you think ADP is called adenosine DIphosphate?
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 How is ADP formed?
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