Oxidative Phosphorylation Flashcards
What is the direct generation of ATP by the action of kinases called?
Substrate-level phosphorylation.
The bulk of cellular ATP is generated in the mitochondria in a process known as what?
Oxidative phosphorylation.
Where does OP take place?
The reactions of oxidative phosphorylation take place in the inner membrane, in contrast to the Krebs Cycle reactions which occur in the matrix.
How does the cristae allow for more OP?
Numerous folds within the cristae increase the surface area upon which oxidative phosphorylation can take place.
Are the ΔGs of the redox reactions of NADH and FADH2 higher or lower than the ΔG of the hydrolysis of ATP?
Higher
What are the four membrane proteins in the electron transport chain?
Complex I (a.k.a NADH-Q oxidoreductase or NADH dehydrogenase)
Complex II (a.k.a. Succinate-Q reductase or succinate dehydrogenase)
Complex III (a.k.a. Q-cytochrome C oxidoreductase)
Complex IV (a.k.a. cytochrome c oxidase)
What are the two mobile carriers for the ETC?
Co-enzyme Q (a.k.a. ubiquinone)
Cytochrome C
What complexes accept electrons and what does this do?
Complexes I, III and IV accept electrons and in doing so, a proton (H+) from the aqueous solution. As electrons pass through each of these complexes, a proton is passed or ‘pumped’ to the intermembrane space.
What does complex II use as a co-factor? What happens to this co-factor?
It uses FAD as a cofactor and can communicate directly with Coenzyme Q which is also in the membrane.
As electrons are passed from FADH2 to Coenzyme Q it also picks up a pair of protons, thereby regenerating FAD and forming QH2.
Why does using FADH2 result in less ATP than NADH?
Since we have effectively bypassed complex I, fewer protons are pumped to the intermembrane space when FADH2 is reoxidized compared with NADH.
As protons flowing back into the matrix via ATP synthase are used to generate ATP, fewer ATP molecules are generated from the reoxidation of FADH2 compared to NADH.
What is ATP synthase and what is its structure??
ATP synthase is a multimeric enzyme consisting of a membrane bound part, F0, and a F1part which projects into the matrix space.
What does the rotation of the enzyme do?
Rotation of the enzyme drives transitions states, with altering affinities for ATP and ADP. As a consequence, conformational energy flows from the catalytic subunit into the bound ADP and Pi to promote the formation of ATP (chemical energy).
What does the direction of the rotation of the enzyme dictate?
The direction of proton flow dictates ATP Synthesis v ATP Hydrolysis, i.e. depending on the direction of the flow of protons through the ATP synthase, the complex can either generate ATP or consume it.
Where do the protons move if ATP is being made?
Net movement of protons flowing into the matrix means ATP is made.
Where do protons move if ATP is being destroyed?
Net movement of protons flowing out of the matrix means ATP is consumed.
