lipids as respiratory substrates

• when are lipids used as a respiratory substrate


  when carbohydrate levels are low
• how much energy do lipids contain per unit gram when compered with carbohydrates


  x2
• what needs to happen to lipids before they can be used for energy


  they need to be hydrolysed
• how many water molecules are need to hydrolyse a lipid and why


  3 to break each ester bond
• what are lipids broken down into


  3 fatty acids and glycerol
• what is the name of the bonds broken when lipids are hydrolysed

  ester bonds
• what happens to the glycerol produced when lipids are hydrolysed


  it will be phosphorylated by ATP,dehydrogenated and converted into a trios phosphate
• what happens to the trios phosphate that is produced when glycerol is phosphorylated and dehydrogenated


  it is an intermediate for glycolysis
• what happens to the fatty acid chains produced when lipids are hydrolysed


  these long hydrocarbon chains are split into 2C acetate fragments
• where are 2C acetate fragments used


  they are combined with a coenzyme and enter the kerbs cycle as acetyl coenzyme
• Why are very large numbers of ATP produced from the hydrolysis of lipids


  Each fatty acid produces many 2C fragments which means the Krebs cycle can go many times producing large numbers of reduced NAD and reduced FAD to fuel the ETC
• Why does the precise number of ATP molecules produced depend upon the length of the hydrocarbon chain of the fatty acid?


  the hydrocarbon needs to be spilt into 2C acetate fragments to be used in the Krebs cycle
• what is another name for acetate


  ethanoic acid