Aerobic Respiration

• aerobic respiration

  glucose + oxygen = carbon dioxide + water

  c6h12o6 + 6o2 = 6co2 + 6h20
• mitochondria structure

  • matrix - containe enzymes for the krebs cycle and the link reaction, also contains mitochondrial DNA
  • cristae - projections of the inner membrane which increases the surface area for oxidative phosphorylation
  • inner mitochondrial membrane - contains electron transport chains and ATP synthase
  • outer mitochondrial membrane - separates the contents and outside of the cell, creating perfect conditions for aerobic respiration
  • intermembrane space - proteins pumped into this space by electron transport chain
  • 70s ribosome - used for protein synthesis
• aerobic respiration:

  • Glycolysis
  • Link Reaction
  • Krebs cycle
  • Oxidative Phosphorylation (electron transport chain)
• ATP releases 30.5 KJ/mol of energy time it is hydrolysed

  ADP + P = ATP + H2O = +30.5KJ/mol
• Glycolysis

  • cytoplasm
  • breakdown of glucose into pyruvate
  • forms 2 ATP, 2 reduced NAD and 2 pyruvate
• Link reaction

  • matrix
  • conversion of pyruvate into acetyle CoA
  • per pyruvate it forms 1 acetyle CoA, 1 reduced NAD and 1 carbon dioxide
• Krebs Cycle

  • matrix
  • series of reactions starting with acetyle CoA
  • per acetyle CoA it forms 1 ATP, 3 reduced NAD, 1 reduced FAD and 2 carbon dioxide
• Oxidative phosphorylation

  • inner mitochondrial membrane
  • transfer of electrons through protons, creating a proton gradient that allows the synthesis of ATP
  • makes approx 30 ATP and water
• Glycolysis steps:

  1. phospholylation - two phosphates, released from the two ATP molecules attach to glucose forming a hexose biphosphate
  2. lysis - destabilises molecule causing it to split into two triose phosphate molecules
  3. phosphorylation - another phosphate is added to the two triose phosphates forming two triose bis-phosphate
  4. two triose bis-phosphates are oxidised by the removal of hydrogen to form two pyruvate. NAD accepts the removed hydrogen's, forming two reduced NADS
• Link reaction (oxidative decarboxylation)

  1. pyruvate enters matrix by active transport
  2. carbon dioxide is removed (decarboxylation) and diffuses out as a waste product and hydrogen is removed (oxidation)
  3. the hydrogen that was removed is accepted by NAD, which becomes reduced NAD
  4. pyruvate is catalysed by coenzyme A to form acetyle CoA
• link reaction

  pyruvate = (co-enzyme A) acetyle CoA

  • releases by product of carbon dioxide
  • reduced NAD (NADH)
• Krebs cycle

  1. acetyle CoA (2-carbon) combines with Oxaloacetate (4-carbon) to form citric acid (6-carbon)
  2. citric acid undergoes decarboxylation (removal of co2 x2) and dehydrogenation (removal of hydrogen) this is accepted by NAD to form three molecules of reduced NAD and one molecule of reduced FAD.
  3. one ATP is synthesised by substrate level phosphorylation
  4. oxaloacetate is regenerated to continue the cycle
• Difference between NAD and FAD:

  • NAD accepts one electron and one proton when it is reduced, FAD accepts two protons and two electrons when it is reduced.
  • NAD participates in all stages of respiration, while FAD only accepts protons and electrons in the Krebs cycle.
  • NAD results in the synthesis of three ATP molecules, while FAD results in the synthesis of two ATP molecules.
• Oxidative phosphorylation

  1. hydrogen is released from reduced NAD and FAD, transferring protons and electrons into the matrix
  2. electrons pass down electron transport chain, releasing energy at each stage
  3. energy used to actively transport protons across the inner membrane, from the matrix to the inter membrane space
  4. accumulation of protons form an electrochemical gradient
  5. protons move back into the matrix through ATP synthase, catalysing conversion of ADP and phosphate into ATP - chemiosmosis
  6. Oxygen is the final electron acceptor, and combines with electrons and protons to form water
• aerobic respiration forms approx 34 ATP per glucose molecule
• substrate level phosphorylation - the production of ATP by the addition of a phosphate to ADP without the use of an electron transport chain