ATP

• • Plants and animal cells release energy from glucose - this process is called respiration
  • A cell can't get its energy directly from glucose. So, in respiration, the energy released from glucose is used to make ATP
  • ATP is made from the nucleotide base adenine, combined with a ribose sugar and three phosphate groups. Its what's known as a nucleotide derivative because its a modified form of a nucleotide
  • Once made, ATP diffuses to the part of the cell that needs energy. The energy in ATP is stored in high energy bonds between the phosphate groups. Its released via hydrolysis reactions
• • When energy is needed by a cell, ATP is broken down into ADP and Pi (inorganic phosphate). This is a hydrolysis reaction
  • A phosphate bond is broken and energy is released. The reaction is catalysed by the enzyme ATP hydrolase
• • ATP hydrolysis can be coupled to other energy-requiring reactions in the cell - this means the energy released can be used directly to make the coupled reaction happen, rather than being lost as heat
  • The released inorganic phosphate can also be put to use - it can be added to another compound, which often makes the compound more reactive
  • ATP can be resynthesises in a condensation reaction between ADP and Pi. This happens during both respiration and photosynthesis, and is catalysed by the enzyme ATP synthase