2.3 - Energy and ATP

•  what's ATP?


  a phosphorylated macromolecule

  known as a nucleotide derivative because it's a modified form of a nucleotide
• components of ATP


  adenine (purine base)

  ribose (penrose sugar)

  3 phosphate groups
• what does ATP stand for?

  Adenosine Triphosphate
• hom does ATP store energy?

  in high energy bonds between phosphate groups - they have a low activation energy so are easily broken
• hydrolysis of ATP


  ATP hydrolaserbreaks a phosphate bond in ATP to form ADP and an inorganic phosphate in a hydrolysis reaction

  as bonds break energy is released
• how much energy is produced from the hydrolysis of 1 mole of ATP?

  30.7 kJ of energy
• synthesis of ATP


  ATP Synthase converts ADP into ATP in a condensation reaction
• ways synthesis of ATP occurs

  in chlorophyll-containing plant cells during photosynthesis (photophosphorylation)

  during respiration in plant & animal calls (oxidative phosphorylation)

  in plant & animal calls when phosphate groups are transferred from donor molecules to ADP (substrate- level phosphorylation)
• phosphorylation


  attachement of a phosphate group to a molecule or ion
• why is ATP a bad long-term energy store?

  it's phosphate bonds aren't stable
• good long-term energy stores

  fats & carbohydrates
• why do calls not store large quantities of ATP?

  it's an immediate energy source

  ATP is rapidly reformed from ADP &Pi so can be reused
• why is ATP a better energy source than glucose?

  each ATP molecule releases less energy than each glucose molecule so energy is released in smaller more manageable quantities

  hydrolysis of ATP is a simple reaction that releases immediate energy while breakdown of glucose is a long series of reactions so energy release takes longer
• making & storing ATP

  can't be stored so has to be continuously Made within the mitochondria
• uses of ATP


  metabolic processes: provides energy to build up macromolecules from their basic units

  movement: provides energy for musule contraction & for filaments of muscle to slide past one another so shorten overall length of muscle fibre

  secretion: needed to form lysosomes

  activation of molecules: Pican phosphorylate other compounds to make them more reoutive so lower the activation energy in enzyme catalysed reactions