Terminal Respiration

Question 1

Citric acid cycle/krebs cycle

Answer 1

It is a common metabolic process for all fuel molecules. It occurs in the mitochondrial matrix. It takes electrons and passes them on to form NADH and FADH2 which enter the elctron transport chain. 1 turn yields 3 NADH, 2 CO2, 1 FADH2 and 1 GTP.

Question 2

Electron transport chain

Answer 2

The final stage of respiration occuring in the mitochodrial matrix and the intramembraneous space. There are 4 membrane bound proteins.

1. NADH-Q oxidoreductase; reduces NADH and passes the electrons to ubiquinone forming ubiquinol. It pumps H+ ions into the intramembraneous space.
2. Succinate-Q reductase; reduces FADH2 passing electrons to ubiquinone forming ubiquinol.
3. Q-cytochrome c oxidoreductase; takes electrons from ubiquinol and passes them to cytochrome c pumping H+ ions into the intramembraneous space.
4. Cytochrome-C oxidase; takes electrons from cytochrome C and passes them to O2 pumping H+ ions into the intramembraneous space.

Question 3

Proton concentration gradient

Answer 3

The pumping of protons sets up a proton gradient across the inner mitochodrial membrane of the mitochondrion. Proton motive force (PMF - promotes movement of protons across membranes down the electrochemical gradient) pushes the protons back through the membrane to make up the difference in concentration. As the protons pass through the membrane, energy is released which ATP synthase uses to turn ADP+Pi into ATP; binding change mechanism. ATP synthesis is dependant on a conformational change in ATP synthase generated by rotation of the gamma subunit.