Oxidative phosphorylation Flashcards
Describe the main concepts of oxidative phosphorylation
-Energy from oxidation of fuel by TCA cycle conserved in NADH and FADH2
-Energy in NADH and FADH2 converted into ATP by oxidative phosphorylation
-This occurs across the inner membrane of the mitochondrion
Describe NAD+
-Electron accepting coenzyme
-Accepts pair of electrons
-Is not bound to enzyme – once it is reduced it leaves enzyme and can inhibit others
The conversion of NAD+ to NADH
The conversion of FAD to FADH2
Describe FAD
-Electron accepting coenzyme
-Only accepts single electrons (x2)
-Is tightly bound to its enzyme (eg succinate dehydrogenase)
Describe ATP
-Contains three phosphate groups
-These repel each other creating strain on bonds
-Requires energy to keep phosphates together
-This energy released when bonds are broken
How is the energy from NADH and FADH2 converted into the high energy bonds of ATP?
The electron transport chain
Describe the electron transport chain
-Oxidises NADH and FADH2 and donates electrons to O2, forming H2O
-Composed of series of large protein complexes
-Electrons pass through these in series of oxidation-reduction reactions
-This process pumps protons from the matrix across the inner mitochondrial membrane
-The protons then fall back into the matrix through an enzyme, ATP synthase
-This catalyses the formation of ATP
Describe ATP synthase
Generates ATP
Multisubunit enzyme
Spans inner mitochondrial membrane
F1 unit contains three catalytic sites
F0 unit forms a rotor
Influx of protons turns rotor, changing conformation of one active site in F1 unit and releasing a molecule of ATP
Describe uncoupling
ATP synthesis can be uncoupled from electron movement
- protons leak back into matrix
- bypass ATP synthase and therefore no ATP is made
Name 3 types of uncoupling
Chemical
Physiological
Proton leak
Describe chemical uncouplers
Chemicals which transport protons across the inner membrane
Destroy proton gradient
- no ATP
