ATP

• A single molecule of adenosine triphosphate (ATP) is a nucleotide derivative and is formed from a molecule of ribose, a molecule of adenine and three phosphate groups
• ATP structure

  A) Ribose

  B) Adenine

  C) Phosphate group

  
• Hydrolysis of ATP to adenosine diphosphate (ADP) and an inorganic phosphate group (Pi ) is catalysed by the enzyme ATP hydrolase
• The hydrolysis of ATP can be coupled to energy-requiring reactions within cells
• The inorganic phosphate released during the hydrolysis of ATP can be used to phosphorylate other compounds, often making them more reactive
• ATP is resynthesised by the condensation of ADP and Pi . This reaction is catalysed by the enzyme ATP synthase during photosynthesis, or during respiration
• ATP is a constant source of energy for biological processes
• Properties of ATP

  • Release energy in small amounts - no energy is wasted compared to glucose and cells don't waste heat energy
  • Small and soluble - move around cytoplasm with ease for chemical reactions (similar to glucose)
  • Only one bond is hydrolysed to release energy - energy release is immediate
  • Transfer energy by transferring its phosphate group
  • Can't pass out the cell - has constant supply of ATP unlike glucose