Oxidative Phosphorylation

Standard reduction potential (E^o’)

A measure of the tendency of a substance to gain electrons; the more positive the value=the greater the tendency

delta E^o’ =

E^o’ (e acceptor) - E^o’ (e donor)

Electrons move spontaneously from a substance with __ reduction potenetial to the substance with __ reduction potential

lower; higher

delta G^o’ =

-nF(deltaE^o’ )

Outer membrane of mitochondria:

Permeable to small molecules and ions

Inter membrane space:

TCA Occurs here

Mitochondrial matrix:

contains enzymes and amino acid metabolism

Inner membrane of mitochondria

ETC is embedded here

Complex I:

• NADH dehydrogenase

• transfer electrons from NADH to QH₂

• For each electron dropped off by NADH to Q, 4 H+ will be pumped into the intermembrane space

Complex III:

• Occurs in 2 cycles known as the Q cycle

• Cytochrome C oxidoreductase

• Can only carry 1 electron at a time

• For 2 QH₂ molecules that drop off their electrons, 2 cytochrome c molecules get reduced, and 4 H+ are pumped into the intermembrane space

Complex IV:

• Cytochrome c Oxidase

• Cytochrome to O2

• For every 2 cytochrome c molecules that drop off their electrons, 1 H2O is produced and 2 H+ are pumped into the intermembrane space

Intermembrane space is the _ side

P

Matrix is the _ side

N

ATP/ADP translocase

Exchange ATP and ADP across the innermembrane

Phosphate transporter

Imports phosphate for ATP synthesis

Protons driven out of the matrix into the intermembrane space set up an __

electrochemical gradient

ATP synthesis is driven by ____

proton-motive force

F₀:

transmembrane protein that allows H+ to flow across membrane; uses electrochemical gradient (c ring + protein)

F₁:

forms ATP through movements of alpha and beta subunits around a stalk (3 alpha + 3 beta subunits around y shaft)

Mechanism of p+ transport by F₀:

p+ enter from N side and bind to c subunit, c subunit spins away from a and releases H+ to P side.

Mechanism of F₁ subunit:

Rotation of y allows for mechanical energy (p+ pumping) to be converted to chemical energy, beta subunit contains the ADP binding site; 3 ATP molecules are made for every 8 H+ that are pumped through

____ signal the need for energy

AMP, ADP, NAD+

____ signal the abundance of energy available

ATP, NADH