respiration

• 4 main stages in aerobic respiration?

  1. glycolysis
  2. link reaction
  3. krebs cycle
  4. oxidative phosphorylation
• where does glycolysis occur?

  cyptoplasm
• where does link reaction occur?

  mitochondrial matrix
• where does krebs cycle occur?

  mitochondrial matrix
• where does oxidative phosphorylation occur?

  membrane of cristae
• glycolysis?

  • glucose phosphorylated using atp producing 2 molecules of triose phosphate
  • tp oxidised & becomes 2 molecules of pyruvate
  • hydrogen released from tp used to reduce nad - nadh
  • atp also produced by substrate level phosphorylation
  • net gain of 2x atp
• how does pyruvate from glycolysis enter mitochondria?

  active transport
• give summary equation for link reaction?

  pyruvate + NAD + coenzyme a - acetyl coA + NADH + carbon dioxide
• briefly describe what happens in krebs cycle?

  • atp produced by substrate level phosphorylation
  • produces NADH & FADH & carbon dioxide from decarboxylation
• what is the electron transfer chain?

  series of carrier proteins embedded in membrane of cristae of mitochondria
• what happens in electron transport chain?

  • nadh/fadh release hydrogen which splits into protons & electrons
  • electrons move down electron transport chain releasing energy
  • energy used to pump protons from matrix into intermembrane space
  • oxygen final electron accepter on etc
• how does chemiosmosis produce atp during aerobic respiration?

  hydrogen moves down proton gradient via atp synthase which provides energy for adp + pi = atp
• how is proton gradient established during chemiosmosis in aerobic respiration?

  some energy released from etc coupled with active transport of hydrogen from matrix into intermembrane space
• role of oxygen in aerobic respiration?

  final electron acceptor in etc
• benefit of electron transport chain rather than single reaction?

  energy released gradually so less energy released as heat
• 2 alternative respiratory substances?

  1. amino acids - proteins
  2. fatty acids & glycerol - lipids
• how can lipid act as alt respiratory substrate?

  • phosphorylation of lipids - tp for glycolysis
  • fatty acids - acetate enters link reaction so hydrogen produced for oxidative phosphorylation
• how can amino acids act as alt respiratory substrate?

  deamination produces:

  • 3 carbon compounds - pyruvate for link reaction
  • 4/5 carbon compounds - intermediates in krebs
• stages in respiration that produce atp by substrate level phosphorylation?

  glycolysis & krebs
• advantage of producing ethanol/lactate during anaerobic respiration?

  converts NADH back into NAD so glycolysis can continue
• what happens to lactate produced in anaerobic respiration?

  transported to liver via bloodstream where its oxidised to pyruvate

  can enter link reaction/be converted to glycogen
• how is ethanol produced in anaerobic respiration?

  ethanal reduced into ethanol
• disadvantage of producing ethanol?

  dissolves cell membranes
• disadvantage of producing lactate?

  acidic so decreases ph

  leads to muscle fatigue
• compare aerobic & anaerobic respiration?

  both: involve glycolysis, require nad, produce atp
• contrast aerobic & anaerobic respiration?

  aerobic: produces atp by substrate level & oxidative phosphorylation, produces more atp, does not produce ethanol/lactate

  anaerobic: produces atp by substrate level phosphorylation ONLY, less atp produced, produces ethanol/lactate
• where does anaerobic respiration occur?

  cyptoplasm
• krebs cycle?

  • oxaloacetate binds with acetyl from acetyl coa forming citrate
  • citrate decarboxylated & oxidised producing 5c compound, co2 & NADH
  • 5c compound further decarboxylated & oxidised reforming oxaloacetate & producing co2, NADH, FADH
  • atp also produced by substrate level phosphorylation
• oxidative phosphorylation?

  • NADH/FADH release hydrogen which splits into protons & electrons
  • electrons move down electron transport chain releasing energy
  • energy used to pump protons from mitochondrial matrix into intermembrane space producing electrochemical gradient
  • protons move down gradient back into matrix via atp synthase providing energy for adp + pi - atp
  • oxygen - final electron acceptor - combines with protons & electrons to form water
• link reaction?

  • occurs in matrix
  • pyruvate oxidised & decarboxylated into acetate
  • hydrogen released from pyruvate used to reduce nad - nadh
  • acetate combines with coenzyme A to form acetyl coenzyme A
• how atp is made in mitochondria?

  • krebs cycle:
  • atp produced by substrate level phosphorylation
  • produces nadh & fadh
  • oxidative phosphorylation:
  • nadh/fadh released hydrogen which splits into protons & electrons
  • electrons passed along etc releasing energy
  • energy used to create proton gradient across inner mitochondrial membrane
  • movement of protons through atp synthase provides energy needed for adp + pi = atp
• anaerobic respiration in animal cells?

  in absence of oxygen glycolysis is only source of small amount of atp anaerobic respiration regenerates NAD so glycolysis can continue

  • pyruvate produced in glycolysis is reduced using NADH
  • this regenerates NAD & produces lactate which causes muscle fatigue
• anaerobic respiration in plant & yeast cells?

  in absence of oxygen glycolysis is only source of small amount of atp anaerobic respiration regenerates NAD so glycolysis can continue

  • pyruvate produced in glycolysis is decarboxylated producing CO2 & ethanol
  • ethanal is reduced using NADH
  • this regenerates NAD & produces ethanol
  • products of this are ethanol (alcohol), co2 so this is used in fermentation to produce beer