Biochem- ETC & Oxidative P I & II Flashcards
What is oxidative phosphorylation?
It is the process by which ATP is formed from the transfer of electrons from NADH and FADH2 to O2 via the electron transport chain (ETC).
Explain the couple rxn between ADP and the formation of ATP to NADH and FADH2.
The nonspontaneous rxn of joining ADP to an inorganic phosphate to from ATP is couples with the oxidation rxn of NADH or FADH2.
Describe the role of the inner membrane of the mitochondria to the ETC.
The inner membrane:
1. Consist of fold-like projections, cristae, that increase the surface area to maximize energy production.
2. Consist of protein complexes involved in the ETC.
3. Envelops a matrix and consist of mitochondria DNA, ribosomes, enzymes and metabolites.
4. Increase H+ concentration generates a membrane potential across the inner membrane.
List the 3 key steps in the synthesis of ATP and its coupled rxn with the oxidation of NADH and reduction of O2.
- Electrons are transferred from NADH to O2 via electron carriers.
- The transfer for electrons by these carriers generate a proton (H+) gradient across the inner mitochondria membrane.
- When H+ spontaneously diffuses back across the inner mitochondrial membrane, ATP is synthesized.
What is the source of energy for ATP synthesis?
The proton motive force.
What is the significance of CoQ in the ETC?
It is the common electron acceptor for Complex I and II.
Remember: NADH only works and gives up its e- @ C1, whereas FADH2 only works and gives up its e- on C2.
What is the final and ultimate electron acceptor of the ETC?
O2, which splits into two oxygen ions where protons are added to form two H2O.
State the pathway of the ETC.
NADH gives an electron to Complex I and passes it e- to CoQ.
FADH2 gives its electron or Complex II and passes it to CoQ, therefore,
E- are transferred from Complex I — Complex II — CoQ — Complex III — CytC — Complex IV — O2.
Which complexes are supercharged by e- and pumps protons from the mitochondrial matrix into the inter membrane space?
Complex I, III, IV
Note: they create proton gradients and pump 4 protons (H+) into the the inter membrane space.
Explain the electron transfer of Complex I (NADH Dehydrogenase) in ETC.
The electron transfer of H+ from NADH into the complex to FMN — series of Fe-S centers — Fe- S protein N2.
N-2 then transfers the protein to CoQ
Explain the electron transfer of Complex II (Succinate Dehydrogenase) in ETC.
E- transfer from succinate — FAD — Fe-S centers — CoQ
State the inhibitors of the ETC and which complex they inhibit.
RAPCAC
Rotenone- Complex I
Piericidin A
Antimycins - Complex III
Cyanide - Complex IV & CytC
Carbon monoxide - Complex IV & CytC
Azide.
State the inhibitors of the ATP synthasis
Oligomycin
Dicylo Hexyl carbo diimide (DCCD)
