ATP

• what does ATP stand for?


  adenosine triphosphate
• what happens during respiration?

  - the energy stored in glucose is not released directly, instead the energy released is used to form ATP

  - ATP is then hydrolysed, providing energy for processes in the cell
• what is ATP made of?

  - adenine

  - ribose sugar

  - 3 phosphate groups
• examples of what energy is used for in a cell

  - active transport

  - synthesising molecules

  - mitosis

  - muscle contraction
• using ATP to release energy

  - high energy bond between 2nd and 3rd phosphate is broken using hydrolysis

  - this forms adenosine diphosphate (ADP) and an inorganic phosphate (Pi)

  - the reaction requires the enzyme ATP hydrolase

  
  

  ATP + water -> ADP + Pi + energy
• what can the released inorganic phosphate be used for?

  added to other compounds to make them more reactive = phosphorylation
• making ATP

  - made during photosynthesis and respiration

  - made from ADP and Pi via a condensation reaction

  - requires the enzyme ATP synthase

  
  

  ADP + Pi -> ATP + H2O

  
  

  there is a constant cycle in the cell, between ATP being hydrolysed and synthesised
• Iron ions (Fe2+)


  - important component of haemoglobin

  - binds oxygen so that it can be carried by red blood cells to respiring cells
• sodium ions


  - involved in the absorption of glucose and amino acids from the small intestine to the blood by cotransport

  - creation of nerve impulses
• hydrogen ions


  - lower the pH of a solution, changing the protein tertiary structure

  - used in making ATP in photosynthesis and respiration
• phosphate ions


  - makes ATP and DNA and RNA nucleotides

  - added to other molecules to make them more reactive (phosphorylation)

  - makes up the hydrophilic part of the phospholipid bilayer
• strong cohesion between water molecules - biological importance


  - allows water to be pulled up in a continuous column in the xylem of plants

  - gives water surface tension which can support small organisms eg pond skater and form droplets on skin for sweating
• water as a metabolite - biological importance


  water is a metabolite in:

  - hydrolysis reactions

  - condensation reactions

  - photosynthesis (light dependant reaction)

  - respiration (produced in oxidative phosphorylation)
• water as a solvent - biological importance


  - allows chemical reactions to occur in solution

  - allows the transport of substances
• water has a large latent heat of vaporisation- biological importance


  (energy required for a liquid to turn into a gas)

  
  

  - provides a cooling effect by reducing body temperature
• water has a high specific heat capacity - biological importance


  (energy needed to raise the temperature of 1kg of a substance by 1°C)

  
  

  - buffers the change in body temperature

  - makes water a good habitat as the temperature doesn't change too much