Oxidative Phosphorylation Flashcards
What is the proton motive force?
Proton motor force is the force used to drive ATP synthesis across the inner mitochondrial membrane, resulting in two energetic gradients
1. chemical gradient or pH gradient due to different [H+]
2. electrical gradient due to charge difference across membrane
How does the ETC produce a proton gradient?
ETC taking electrons and transporting them from matrix into intermembrane space
pH gradient, from high pH to low pH
What is the chemiosomotic coupling hypothesis?
Removed outer membrane, keep inner membrane in tact - ETC still works
ATP is not synthesised as we have removed outer membrane which is required for the gradient to form (big volume of solution hence few protons won’t change concentration of large membrane)
What is Protein Bacteriorhodopsin?
Protein Bacteriorhodopsin (light inducible) moves proteins from one side of membrane to another (protein pump) increasing concentration of proteins inside vesicle, creating proton gradient. When light switched on ATP made, ETC not present but proton gradient is sufficient for ATP synthesis
What is 2,4-Dinitrophenol (DNP)?
Taking proton gradient away
DNP shuttles H+ from intermembrane space to the matrix, it can shift between two forms hence pick up and drop off proton. This dissipates the proton gradient (picks up proton from intermembrane space and drops off in the matrix). In presence of DNP ETC functions but no ATP is made
What happens if you take DNP?
ETC functions however no ATP is made
Fuel molecules still go through citric acid cycle, B-oxidation and PDH but coenzymes NADH and FADH2 aren’t reduced hence ATP can’t be made
What are the parts of F1FO-ATP synthase?
Parts of ATP that spin = rotor subunits
Parts of ATP that don’t’ spin = stator subunits
Proton drives rotor movement
Rotor movement causes conformational changes in the stator that drives ATP synthesis
How does F1FO-ATP synthase work?
Channel where protons can enter into c subunit. Proton can sit in c-subunits which causes the subunit to start turning and then are released into matrix. Protons are going down their gradient -> gamma stalk to start turning
Alpha beta pairs are where ATP synthesis occurs, when gamma stalk starts to turn it causes a conformational change which its the phosphate onto ADP to make ATP
How does movement of rotor cause conformation change in alpha and beta subunits of F1?
Three alpha-beta pairs, each in a different conformation
O= open, ATP released for cellular function and ADP and Pi can enter for binding and making more ATP
L = loose, holds ADP and Pi in preparation for catalysis
T = tight, phosphate added onto ADP and ATP is made
Conformation changes for each dimer when rotor turns O->L->T
Energy accounting in oxidative phosphorylation
4 protons are pumped per 1 ATP
NADH pumps 10 protons in ETC hence 2.5 ATP are made
FADH2 pumps 6 protons in ETC hence 1.5 ATP are made
2.5+1.5 = 4
