ATP

• ATP is the immediate energy source in a cell, acting as a short term store. ATP drives metabolism and Glucose can be used to make ATP in respiration.
• ATP consists of one adenine (nitrogenous base), one ribose and three phosphate 

  molecules
• The bonds between the phosphate groups are high energy bonds which release energy when they are hydrolysed 
• ATP is synthesised from ADP (adenosine diphosphate) and an inorganic phosphate group (Pi). This is known as phosphorylation.
• The synthesis of ATP involves a condensation reaction with the removal of a water molecule
• When the third phosphate is removed from ATP energy is released. This is a hydrolysis reaction. The reaction is catalysed by the enzyme ATPase
• Hydrolysis of an ATP molecule releases a small amount of energy, this allows energy to be released in small, manageable steps during energy requiring reactions
• Hydrolysis of ATP is a single reaction releasing immediate energy
• As a small, soluble molecule ATP can be transported around the cell easily