Energy is the ability to do work.

All cells get their energy from their metabolism (food).

Energy required for motion is called KINETIC ENERGY.

Stored energy is called POTENTIAL ENERGY.

Energy can neither be created or destroyed (the 1st LAW OF THERMODYNAMICS), so the amount is always constant (the same).

Energy can be converted from one form to another. When energy is converted from one form to another, some of the energy ends up as heat (the 2nd LAW OF THERMODYMANICS).

ATP (ADENOSINE TRIPHOSPHATE)
– ATP is a molecule present in living organisms, it shuttles energy within the cells.
– ATP is one of the major energy-providing molecules that initiates biochemical reactions throughout the body.
– It is a source of potential chemical energy for most enzyme reactions.
– In the cell’s mitochondria, ATP is constantly generated from food.
– All chemical reactions are the transfer of energy from one molecule to another.
– ATP is an ADENOSINE MOLECULE chemically bonded to 3 PHOSPHATE MOLECULES.
– The chemical bonds connecting each phosphate molecule to the adenosine molecule hold energy.
– Energy is stored when bonds are formed to connect a phosphate molecule to an adenosine molecule. When these bonds are broken the energy is released.
– When a cell needs an ATP’s molecules energy, the last phosphate group breaks off and the energy in the bond is released for use by the cell.
– ATP molecules bind to chemicals within the cell that need the energy. This ensures that the energy is transferred from the ATP molecule to the proper place for use.
– Specialized proteins, called ENZYMES, use the energy released from ATP to do all the work of the cell.
– Enzymes are important biological catalysts; they function in lowering the activation energy needed for chemical reaction to occur.
– Enzymes are neither changed nor used up in the reaction.

ADP (ADENOSINE DIPHOSPATE)
– Once the ATP molecule has released energy by breaking off a phosphate molecule, the ATP molecule only has 2 phosphate molecules and is called ADP (ADENOSINE DIPHOSPATE).
– ADP is like an uncharged battery, it has no energy.
– ADP can have another phosphate molecule join it and become an ATP molecule again.