What is ATP?
All living cells require energy, and this energy is provided by respiration.
glucose + oxygen  carbon dioxide + water (+ energy)
The Nature of ATP
Adenosine triphosphate (ATP), the energy currency or coin of the cell, transfers energy from
chemical bonds to endergonic (energy absorbing) reactions within the cell. Structurally, ATP
consists of the adenine nucleotide (ribose sugar, adenine base, and phosphate group, PO4-2) plus
two other phosphate groups. Energy is stored in the covalent bonds between phosphates, with the
greatest amount of energy (approximately 7 kcal/mole) in the bond between the second and third
phosphate groups. This covalent bond is known as a pyrophosphate bond.
We can write the chemical reaction for the formation of ATP as:
a) in chemicalese: ADP + Pi + energy ----> ATP
b) in English: Adenosine diphosphate + inorganic Phosphate + energy produces Adenosine
Triphosphate
http://hyperphysics.phy-astr.gsu.edu/Hbase/biology/atp.html#c2
ADP + P + Energy ---> ATP
The amount of energy stored is about 7,300 calories for every mole of ATP formed.
ATP --> ADP + P + Energy
Again, about 7,300 calories of energy per mole is released. The ADP and the phosphate are then
free to return to the power plant and be rejoined. In this way, ATP and ADP are constantly being
recycled.
http://www.brooklyn.cuny.edu/bc/ahp/LAD/C7/C7_atp.html
ATP is the higher energy form (the recharged battery) while ADP is the lower energy form (the
used battery). When the terminal (third) phosphate is cut loose, ATP becomes ADP (Adenosine
diphosphate; di= two), and the stored energy is released for some biological process to utilize.
The input of additional energy (plus a phosphate group) "recharges" ADP into ATP
What form is this energy in? It’s in the form of chemical energy stored in a compound called ATP
(adenosine triphosphate). So all respiration really does is convert chemical energy stored in
glucose into chemical energy stored in ATP. ATP is a nucleotide, one of the four found in DNA
but it also has this other function as an energy storage molecule. ATP is built up from ADP and
phosphate (PO43-) , abbreviated to Pi):
All the processes in a cell that require energy (such as muscle contraction, active transport and
biosynthesis) use ATP to provide that energy. So these processes all involve ATPase enzymes,
which catalyse the breakdown of ATP to ADP + Pi, and make use of the energy released. So the
ATP molecules in a cell are constantly being cycled between ATP and ADP + Pi.
http://www.biologymad.com/master.html?http://www.biologymad.com/PhotosynResp/PhotosynR
esp.htm