respiration

• stages of aerobic respiration

  • glycolysis
  • link reaction
  • Krebs cycle
  • oxidative phosphorylation and electron transport chain
• stages of anaerobic respiration

  • glycolysis
  • alcoholic fermentation
  • lactic fermentation
• alcoholic fermentation happens in plants. yeast is fermented to ethanal then to ethanol. yeast the ethanal is decarboxylated and looses CO2. ethanal to ethanol is NADH loosing hydrogen to form NAD. NAD is reused in glycolysis. build up of ethanol becomes toxic and can kill the yeast
• glycolysis happens in both aerobic and anaerobic respiration
• glycolysis happens in the cytoplasm
• link reaction happens in the matrix of mitochondria. pyruvate produced in glycolysis is actively transported from cytoplasm to mitochondria matrix
• krebs cycle happens in the matrix of the mitochondria
• oxidative phosphorylation and electron transport chain happens between the membranes of the mitochondria and the matrix
• fats used as a respiratory substrate

  triglyceride has a glycerol molecule which contains 3 carbons which are phosphorylated and used in glycolysis and krebs cycle. fatty acids are broken down to 2 carbon fragments which react with co enzyme a.
• why fatty acids produce a lot of ATP.

  fatty acid chains are long so when hydrolysed produce many 2 carbon fragments. the hydrogen atoms can be used to produce ATP in oxidative phosphorylation.

  1g fat energy = 2x 1g carbohydrate energy
• in cases of starvation tissue proteins will be hydrolysed to amino acids. the amino acid has the amine group removed which is removed by the liver and eliminated by the kidney. the remaining molecule can be used in the respiratory pathway at different points.
• coenzymes of respiration

  • NAD
  • FAD
  • coenzyme A
• glycolysis converts glucose to 2 molecules of 3 carbon pyruvate
• link reaction converts 3 carbon pyruvate to acetyl co A
• krebs cycle converts acetyl co A to 4 carbon oxaloacetate
• oxygen is the final electron acceptor which produces water
• anaerobic respiration is important as it ensures the production of a small amount of ATP in glycolysis. It removes pyruvate or its build up would stop glycolysis. It regenerates NAD from NADH to prevent it running out in anaerobic conditions.
• respirometer is a device that measures rate of respiration for a living organism
• rate of cellular respiration can be measured by

  • measure amount of glucose consumed
  • measure amount of oxygen consumed by respirometer
  • measure amount of CO2 produced with gas syringe
• purpose of a three way tap is to control pressure
• soda lime is used to absorb CO2 produced
• dependent variable of a respirometer is measuring the distance the coloured liquid moves
• three variables to control in respirometer experiment is

  • temperature
  • amount of glucose fed to organism
  • volume oxygen available
• no movement of the coloured liquid suggests a gas leak
• respirometer system must be air tight