ATP

• What is ATP short for ?

  Adenosine Triphosphate
• Why is ATP important?

  1. Plant and animal cells release energy from glucose - respiration
  2. Yet a cell cant get its energy directly from glucose
  3. So in respiration the energy released from glucose is used to make ATP - an immediate energy source - which then transfers energy from the sites of respiration to the parts of the cell which require energy including for active transport, muscle contraction and the formation of large molecules such as proteins ( through ATP hydrolysis)
• What is the difference between glycogen/ triglycerides and ATP?

  ATP is not a long term energy store - its an immediate energy source
• What is ATP made out of ?

  • made from the nucleotide base adenine combined with a ribose sugar and 3 phosphate groups
  • its what's known as a nucleotide derivative because its a modified form of a nucleotide

  
• Where is the energy stored in ATP?

  In high energy bonds between the phosphate groups, its released via hydrolysis reactions
• What happens to ATP once made?

  It diffuses to the part of the cell that needs energy
• How ATP is used...

  1. When energy is needed by a cell , ATP is broken down by into ADP (adenosine diphosphate) and Pi (inorganic phosphate)
  2. This is a hydrolysis reaction - a phosphate bond is broken and energy is released. The reaction is catalyzed by the enzyme ATP Hydrolase.
• ATP Hydrolysis can be 'coupled' to other energy-requiring reactions in the cell- what does this mean?

  • the energy released can be used directly to make the coupled reaction happen - rather than being lost as heat.
  • examples of these coupled reactions = The active transport of ions up a concentration gradient / Muscle contraction and muscle fibre movement
• What can happen to the released inorganic phosphate?

  1. it can be added to another compound ( this is known as phosphorylation) which often makes the compound more reactive
• How is ATP re-synthesized / made ?

  • in a condensation reaction between ADP & Pi
  • This happens during both respiration and photosynthesis
  • Is catalysed by the enzyme ATP synthase
• DIAGRAM:

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