Aerobic respiration

• Stages of aerobic respiration

  1. Glycolysis

  2. Link reaction

  3. Krebs Cycle

  4. Oxidative phosphorylation
• Location of glycolysis


  - Cytoplasm
• Glycolysis


  - Substrate level phosphorylation

  - 2 ATP molecules add 2 phosphate groups to glucose

  - Glucose phosphate splits into two triose phosphate (3C) molecules

  - Both TP molecules are oxidised (reducing NAD) to form 2 pyruvate molecules (3C)

  - Releases 4 ATP molecules
• Coenzyme


  - A molecule which aids / assists an enzyme

  - NAD and FAD in respiration both gain hydrogen to form reduced NAD (NADH) and reduced FAD (FADH)

  - NADP in photosynthesis gains hydrogen to form reduced NADP (NADPH)
• products of glycolysis per glucose molecule

  - Net gain of 2 ATP

  - 2 reduced NAD

  - 2 pyruvate molecule
• How many ATP molecules does glycolysis produce?

  - 2 ATP molecules used to phosphorylate glycose to glucose phosphate

  - 4 molecules generated in oxidation of TP to pyruvate

  - Net gain 2 ATP molecules
• Location of link reaction

  - Mitochondrial matrix
• Link reaction


  - Reduced NAD and pyruvate are actively transported to matrix

  - Pyruvate is oxidised to acetate (forming reduced NAD)

  - Carbon removed and CO2 forms

  - Acetate combines with coenzyme A to form acetylcoenzyme A (2C)

  
• Products of the link reaction per glucose molecule

  - 2 acetylcoenzyme A molecules

  - 2 carbon dioxide molecules

  released

  - 2 reduced NAD molecules
• Products of the link reaction per reaction


  - 1 acetylcoenzyme A molecules

  - 1 carbon dioxide molecules released

  - 1 reduced NAD molecules
• Location of krebs cycle

  - Mitochondrial matrix
• krebs cycle


  - Acetylcoenzyme A combines with 4C molecule to produce a 6C molecule - enters cycle

  - Oxidation-reduction reactions

  
• Products of krebs cycle per glucose molecule

  - 8 reduced coenzymes - 6 reduced NAD, 2 reduced FAD

  - 2 ATP

  - 4 carbon dioxide
• Products of krebs cycle per cycle

  - 4 reduced coenzymes - 3 NADH, 1 FADH

  - 1 ATP

  - 2 carbon dioxide
• Location of oxidative phosphorylation

  - Cristae of mitochondria
• Mitochondria structure


  - Double membrane with inner membrane folded into cristae

  - Enzymes in matrix

  
• Role of reduced coenzymes in oxidative phosphorylation

  - Accumulate in mitochondrial matrix, where they release their protons (H+) and electrons (e-)

  - Regenerate NAD and FAD to be used in glycolysis/ link reaction/ Krebs cycle
• Role of electrons in oxidative phosphorylation

  - Electrons pass down series of electron carrier proteins, losing energy as they move

  - Energy released actively transports H+ from mitochondrial matrix to inter membranal space

  - Electrochemical gradient generated
• How is ATP made in oxidative phosphorylation?

  - Protons move down electrochemical gradient back into matrix via ATP synthase

  - ATP created

  - Movement of H+ is chemiosmosis
• Role of oxygen In oxidative phosphorylation

  - Oxygen is the final electron acceptor in electron transport chain

  - Oxygen combines with protons and electrons to form water enables the electron transport chain to continue
• How would lack of oxygen affect respiration?

  - Electrons can't be passed along the electron transport chain

  - The Krebs cycle and link reaction stop because NAD and FAD (converted from reduced NAD/FAD as they release their H atoms for the ETC), cannot be produced
• Oxidation


  - Loss of electrons

  - When a molecule loses hydrogen
• Reduction


  - Gain of electrons a reaction where a molecule gains hydrogen