Electron Transport Chain · Stage 4: Electron Transport Chain Located on the inner membrane of the mitochondria Uses NADH and FADH2 5 components to the ETC ordered by increasing electronegativity

Electron Transport Chain

Oxidative Phosphorylation

Wednesday, October 18, 17

Stage 4: Electron Transport Chain

Located on the inner membrane of the mitochondriaUses NADH and FADH2

5 components to the ETC ordered by increasing electronegativity



NADH dehydrogenase


NADH Dehydrogenaseweakest attractor of electrons in the chainNADH → NAD+ + H+ +2e-

H+ get pumped across the membrane into inter-membrane space2e- get transferred across the chainNAD+ travels back to the Krebs cycle to be recycled


Q


Ubiquinone (Q)

Accepts 2e- and carries them to the next component


Cytochrome b-c1 Complex


Cytochrome b-c1 Complex

Carries 2e- to cytochrome CUses the energy from 2e- to transport a second more H+ ion into the inter-membrane space of the matrix


Cytochrome C


Cytochrome C

Carries electrons to the next component


Cytochrome Oxidase Complex


Cytochrome Oxidase Complex

Accepts 2e- from cytochrome CFinal H+ ion pumped across the matrix


O2


The role of oxygen

Oxygen acts as the final electron acceptor, the most electronegative.O2 splits and combines with free H+ in the matrix to form H2O


The role of oxygen

Without oxygens electrons pile up, no more H+ pumped across, no more energy created



NADH vs FADH2

NADH transfers electrons to NADH dehydrogenase, results in 3 H+ being pumped acrossFADH2 transfers electrons at ubiquinone, results in 2 H+ being pumped across



ChemiosmosisETC create a concentration gradient of H+ ions between mitochondrial membranesATP synthase pumps H+ back into the matrix

each time H+ is pumped, free energy is available to create an ATP



Total ATP CountGlycolysisGlycolysis

Pyruvate Oxidation

Krebs CycleKrebs CycleKrebs Cycle

2 ATP2 ATP2 NADH2 NADH

2 ATP2 ATP6 NADH2 FADH2



Pyruvate Oxidation


2 ATP2 ATP2 NADH2 NADH 6 ATP

2 ATP2 ATP6 NADH 18 ATP2 FADH2 4 ATP


NADH is impermeable to the outer membrane of the mitochondria.

Therefore the NADH created in glycolysis is ‘handed off’ to FADH2 via a channel



Pyruvate Oxidation


2 ATP2 ATP2 NADH 4 ATP2 NADH 6 ATP




Pyruvate Oxidation


TOTAL

2 ATP2 ATP2 NADH 4 ATP2 NADH 6 ATP


36 ATP36 ATP


Methods of Control

phosphofructokinaseEnzyme required in step 3 of glycolysis

Inhibited by ATP and citrateStimulated by ADP


Methods of Control

pyruvate decarboxylaseEnzyme needed to make Acetyl CoA

Inhibited increasing NADH concentration


Documents

Electron Transport Chain · Stage 4: Electron Transport Chain Located on the inner membrane of the mitochondria Uses NADH and FADH2 5 components to the ETC ordered by increasing electronegativity