Oxidative Phosphorylation Flashcards
Why do we need Oxidative Phosphorylation
1.Homeostasis (normal cellular functions)
2.Major source of energy in the form of ATP (RBC exception)
Is the ETC exergonic?
Yes, Highly exergonic
Q-pool
between 1 and 3 , getting electrons from 1 and 2
Coenzyme Q or Ubiquinone is NOT
a protein
Step I: Oxidation of NADH by
NADH-Q Oxidoreductase (Complex I)
Complex II makes
FADH2 and reduces Q
Complex II does not
pump protons!
Step II: Complex II contains
Succinate Dehydrogenase from CAC
Step III: Complex III
Q Cycle
Stage IV: Complex IV
The Reduction of Molecular Oxygen to Water
Products of Complex IV
2 waters (reduced O2)
8 H+ out of matrix, 4 to intermembrane space
Cyt cox recycled
Products of the ETC
2 waters (reduced O2)
10 H+ out of matrix for NADH (only 6 for FADH2)
electrochemical/pH/proton gradient
The Purpose of the Electron Transport Chain is to Create the
Proton Motive Forceaka the “cation gradient”!
The World’s Smallest Molecular Motor”
ATP Synthase
F0 domain
a rotating proton channel in the membrane
F1 domain
stationary ATP Synthase made of nine subunits (a3b3gde)
Protons get Pumped Back into the Matrix Through
F0
ATP Synthase Can Make ATP without a
Proton Motive Force
How many active sites does ATP have
3 Active Sites in the b Subunits in Different Forms
Three Active Sites in the b Subunits
T = tight form (yellow)
L = loose form (blue)
O = open form (green)
When the g (g) subunit touches a b subunit
, it converts to T and holds onto ATP
What drives the formation of the proton motive force
Free energy generated by the reduction of molecular oxygen
one NADH could pump out
~ 10 H+
need ~ 4 H+ per ATP, so
10/4 = 2.5 ATP/NADH
What happens when the Proton Motive Force is disrupted?
Disease (low ATP)
Heat (brown adipose tissue)
Free radical formation (extra e-)
