Respiration

• What is the function of the mitochondria?


  Synthesis of ATP through oxidative phosphorylation
• What is the purpose of the cristae?


  Increasing surface area, site of ATP sythase and oxidative phosphorylation.
• What is the pH of the intermembrane space?


  Acidic
• Where are enzymes, ribosomes and DNA found?


  Matrix
• Why do muscle cells have a large number of mitochondria?


  Because they are more active, requiring larger amounts of ATP for contraction.
• What is the word equation for aerobic respiration?


  glucose + oxygen $\rightarrow$ carbon dioxide + water + ATP
• What are the stages of aerobic respiration?

  1. Glycolysis
  2. Link reaction
  3. Krebs Cycle
  4. Oxidative phosphorylation
• Where does glycolysis occur?


  Cell cytoplasm
• What occurs in glycolysis?


  Glucose is split into two molecules of pyruvate.
• What are the intermediate products of glycolysis?


  Fructose biphosphate, TP, Pyruvate
• What is gained following the link reaction?


  4 ATP, 2 NADH
• When allows aerobic respiration to continue?


  Oxygen is available, allowing pyruvate to enter the matrix via active transport
• What occurs in the link reaction?


  Decarboxylation of pyruvate with NAD, producing carbon dioxide, NADH and acetyl CoA
• Where does the link reaction occur?


  Matrix
• What is the role of coenzyme A?


  Supplies the acetyl group to the Krebs cycle for further stages of respiration
• What are the intermediates in the Krebs Cycle?


  Citrate, 5 carbon compound and oxaloacetate.
• What is gained from the Krebs cycle?


  3 NADH, FADH, ATP
• How is oxaloacetate regenerated?


  Decarboxylation of citrate, oxidation of citrate (H atoms lost) , and substrate-linked phosphorylation of ADP.
• What are FAD and NAD?

  Coenzymes
• What is a hydrogen atom made of?

  H+ and e-
• What is FADH and NADH?

  Reduced coenzymes that have gained a hydrogen
• What is the role of reduced NAD and FAD?

  They transfer hydrogen ions to the electron transfer chain on the inner mitochondrial membrane.
• What happens to FADH and NADH when they lose hydrogen?

  They become oxidised
• Why are hydrogen ions and electrons required in the electron transport chain?

  The electron transport chain creates a proton gradient into the intermembrane space creating energy for ATP synthesis.
• Where does oxidative phosphorylation occur?

  The inner mitochondrial membrane
• What is the chemiosmotic theory?

  Energy for the ETC used to pump protons up the concentration gradient into the intermembrane space. H+ ions then flow back into the matrix by facilitated diffusion through ATP synthase. This creates energy for the phosphorylation of ADP.
• What occurs in oxidative phosphorylation?

  • H+ ions and electrons donated by FADH and NADH from Krebs
  • High energy electrons enter the ETC and release energy as they move through the chain.
  • Energy is used to pump protons into to intermembrane space from the matrix, creating a chemiosmotic gradient.
  • Protons return to the matrix through facilitated diffusion, phosphorylating ADP.
  • Oxygen acts as the 'final electron acceptor', forming water with protons and electrons.
• When does anaerobic respiration occur?

  When there is little or no oxygen available
• Why does anaerobic occur when there's less or no oxygen?

  There is no final electron acceptor meaning the ETC stops functioning so no more ATP is produced by oxidative phosphorylation. No FADH and NADH can be oxidised for the Krebs cycle, causing the cycle to stop.
• What occurs in ethanol fermentation?

  NAD transfers its hydrogens to ethanal to form ethanol.
• What are the stages of ethanol fermentation?

  Pyruvate is decarboxylated, releasing $CO_2$, ethanal is reduced to ethanol using alcohol dehydrogenase. Ethanal is the final electron acceptor and ethanol cannot be further metabolised.
• What occurs in lactate fermentation?

  NAD transfers hydrogens to pyruvate to form lactate, catalysed by lactate dehydrogenase. The final product, lactate, can be further metabolised.
• What can lactate be metabolised to?

  It can be oxidised back to pyruvate which is then channelled into Krebs, or it can be converted to glycogen.
• What is oxygen debt?

  Deficit of oxygen that is needed to oxidise pyruvate, this is why animals breathe deeper and faster after exercise.