Ch 14: Electron Transport & Oxidative Phosphorylation

What are the 3 basic stages of oxidative E generation?

1. C from metabolic fuels into acetyl-CoA

2. TCA cycle oxidized acetyl-CoA, produces CO₂, reduced e- carriers, small amount ATP

3. Reduced e carriers re-oxidized, provides energy for synthesis of more ATP

What process provides most of the energy for ATP synthesis?

Cellular respiration, oxidative phosphorylation: NADH & FADH₂ re-oxidized

Where do electron transport and oxidative phosphorylation occur in the cell?

The inner membrane of the mitochondria.

In simple terms, how does the electron transport chain produce ATP?

• Complex I, III, IV pump protons into the space between membranes as electron pass through.

• This creates a voltage difference.

• Change complex V and it phosphorylates ADP

• Producing ATP

What is the formula for standard free E change in a redox reaction?

ΔGº’ = -nFΔEº’

ΔEº’ = Eº’_acceptor - Eº’_donor

Around ___ H⁺ are transported per NADH molecule oxidized in the ETC.

10 H+

What is the name for the free energy of the proton gradient?

Protonmotive force.

What is the purpose of ATP synthase? What is another name for it?

It phosphorylates ADP using the electrochemical proton gradient.

AKA. Complex V

What takes place in the F₀ and F₁ complexes in ATP synthase?

• F₀ complex transports protons across the membrane along the gradient.

• F₁ complex converts ADP + P_i to ATP

What could happen to the mitochondria that would prevent respiration due to interfering with the ATP synthase process?

A break in the inner membrane.

One full round in the ATP synthase translocates how many protons?

8 protons / round

In ATP synthase, how does the C subunits turning lead to ATP synthesis?

1. Causes γ subunit to rotate

2. γ subunit rotating changes conformation of F₁ complex

3. Chang in αβ dimer conformation is coupled to ATP synthesis

Can ATP and ADP freely diffuse across the mitochondrial membrane?

No b/c they are charged.

How might the inhibition of the TCA cycle affect glycolysis?

Citrate builds up which inhibits the phsophofructokinase reaction in gylcolysis.

How does the ETC chain affect the TCA cycle?

If the ETC is inhibited (scarce ADP), NADH and FADH₂ are accumulated. They then inhibit it the TCA cycle.

What is the purpose of thermogenin, a protein in the inner membrane?

When protons run back along gradient without producing ATP, the protonmotive force E is released as heat.

In ETC, what is the e- acceptor and donor for complex I? How many protons are translocated? What is the redox center?

• Donor: NADH, acceptor: Q

• 4 protons

• FMN

In ETC, what is the e- acceptor and donor for complex III? How many protons are translocated? What is the redox center?

• Donor: QH₂, acceptor: cytochrome C

• 4 protons

• cytochromes

In ETC, what is the e- acceptor and donor for complex IV? How many protons are translocated? What is the redox center?

• Donor: reduced cytochrome C, acceptor: O₂

• 2 protons

• FeS & Cu

In ETC, what is the e- acceptor and donor for complex II? How many protons are translocated?

• Donor: FADH₂ from TCA, acceptor: Q

• 6 protons