Respiration

• aerobic vs anaerobic respiration:

  • can be done with oxygen - aerobically
  • can be done without oxygen - anaerobically
  • both types produce ATP
  • anaerobic produces less
  • both start with the process glycolysis - stages differ after
• mitochondria:

  • the reacts in aerobic respiration take place in the mitochondria
  • folds (cristae) in the inner membrane of the mitochondria provide a large surface area to maximise respiration
• coenzymes:

  • a coenzyme is a molecule that aids the function of an enzyme by transferring a chemical group from one molecule to another
  • the coenzymes used in respiration include, NAD, reduced coenzyme A and FAD
  • NAD and FAD transfer hydrogen from one molecule to another
  • this means they can reduce (give hydrogen to) or oxidise (take hydrogen from) a molecule
  • coenzyme A transfers acetate between molecules
• aerobic respiration:

  there are 4 stages:

  • glycolysis
  • the link reaction
  • the Krebs cycle
  • oxidative phosphorylation
• • the first three stages are a series of reactions
  • the products from these reactions are used in the final stage to produce ATP
• • the first stage happens in the cytoplasm of cells
  • the other three take place in the mitochondria
• • glucose can be used as a respiratory substrate in both aerobic and anaerobic resp
  • however, glucose isn't the only respiratory substrate that can be used in aerobic
  • some products resulting from the breakdown of other molecules, such as fatty acids from lipids and amino acids from proteins can be converted into molecules that are able to enter the Krebs cycle (usually acetyl CoA)
• • anaerobic respiration doesn't involve the link reaction, the Krebs cycle or oxidative phosphorylation
  • the products of glycolysis are converted to ethanol or lactate instead
• glycolysis, the link reaction and the Krebs cycle are basically a series of reactions which produce ATP, NADH, FADH and CO2

  the reduced coenzymes are then used in oxidative phosphorylation to produce loads more ATP
• oxygen is the final electron acceptor in the electron transport chain in oxidative phosphorylation
• the whole purpose of respiration is to produce ATP to fuel biological processes - why it happens continuously
• ATP production can be affected by mitochondrial diseases:

  • affect the functioning of the mitochondria
  • can affect how proteins involved in oxidative phosphorylation or the Krebs cycle function, reducing ATP production
  • may cause anaerobic respiration to increase to try and make up some of the ATP shortage
  • this results in lots of lactate being produced, which can affect muscle fatigue and weakness
  • some lactate will also diffuse into the bloodstream, leading to high lactate concentrations in the blood