Oxidative Phosphorylation

Flashcards for Oxidative Phosphorylation lecture review.

NADH and FADH2

Reduced coenzymes that carry electrons to the electron transport chain.

What powers conformational changes in protein complexes?

Change in redox potential.

What do protein complexes do?

Pumps protons from the matrix into the intermembrane space.

What is used by ATP synthase to make ATP in the matrix?

The proton gradient.

Complex I

Passes electrons from NADH to Coenzyme Q (ubiquinone).

How many subunits are in Complex 1?

45 polypeptide subunits, including 14 ‘core’ essential subunits.

The Electron Transport ‘Chain’

Transfer of electrons from carrier to carrier.

The electron transfer potential of each carrier is

Measured by a standard reduction potential, E´0.

Good reducing agents

Give up electrons easily and have negative E´0 values.

Strong oxidizing agents

Have a greater affinity for electrons and have positive E´0 values.

Inhibitors of electron flow from complex I to CoQ

Rotenone and amytal.

Antimycin A

Blocks Complex III.

Inhibitors of Complex IV

Cyanide, azide, and CO.

Oligomycin

Inhibits ATP synthase (complex V).

Uncouplers

Disrupt the H+ gradient, affecting ATP synthesis.

Uncouplers are molecules that have

Hydrophobic groups that allow them to cross the membrane.

Peter Mitchell’s Chemiosmotic Hypothesis

Electrochemical gradient across the mitochondrial inner membrane.

Proton-motive force

Driving force behind ADP to ATP conversion.

F1

Peripheral protein unit that carries out the catalytic synthesis of ATP in the matrix.

F0

Integral membrane protein unit that anchors the enzyme complex in the inner mitochondrial membrane.

Each β subunit undergoes a conformational change between 3 states:

Open or Empty/exit (ATP leaves), Loose - ADP and Pi bound, Tight - ATP bound

What can be used to visualize this rotation in the F1 unit using recombinant fusion proteins and fluorescence microscopy?

Imaging techniques.

The P/O ratio tells you

How many ATPs (P) are made per Oxygen reduced to water (2 e- from donor).

P/O for NADHcytosol

1.5

P/O Ratio Exceptions

NADHcyt from glycolysis cannot be imported across the inner mitochondrial membrane for use in the ETC.

Mitochondria produce up to ___ of a eukaryotic cell's energy (ATP)

95%

During periods of limited oxygen

The Electron Transport Chain shuts down and anaerobic metabolism occurs.

Lactate dehydrogenase uses NADH made in glycolysis in the cytoplasm for what purpose?

Replenishing NAD+ for glycolysis to continue.

What drives the pumping of protons across the inner mitochondrial membrane?

A change in redox potential in the Electron Transport Chain.

What is important for cellular metabolism?

Inhibitors, oxygen availability, and regulation.