L12 - The Electron Transport Chain

Outer membrane of mitochondria allows

small molecules and ions to pass and is freely permeable

Inner membrane of mitochondria is impermeable to

most small molecules and ions

Inner membrane space is between

inner membrane and outer membrane

Inside inner membrane is the

matrix

Inner membrane have integral membrane proteins for

ETC and transport proteins

Energy is transduced and captured through

electron transport

More negative reducing potential (greater tendency to donate electrons drives the electron transport to

more positive reducing potential (greater tendency to accept electrons)

DeltaE =

acceptor - donor

DeltaG =

-nFDeltaE

Hydrolysis of ATP has a high negative DeltaG and is ___________ than the synthesis of ATP

7x more energy

Inhibitors are used to determine sequence events of

electron transfer

NADH is reduced form of

NAD+

FADH2 is fully reduced from of

FAD

FAD and FMN accept electrons

one at a time

Heme are

iron containing porforin ring

Hemes are part of

cytochrome

Cytochrome is an

electron carrier and has three classes a, b, and c

Ubiquinone (CoQ/Q) is a

lipid soluble that has a long hydrocarbon change and freely diffuses in the inner mitochondria membrane. Can accept one or two electrons.

Q is fully

oxidized

QH is

semiquinone

QH2 is fully

reduced - ubiquinol

Iron sulfur centers participates in

one electron transfer

Complex 1

• Large L shape enzyme

• Firmly embedded in the inner membrane

• Catalyzes NADH + H + Q -> NAD+ and QH2

• Exergonic 

• Endergonic of protons from matrix (n) to intermembrane space (p)

• Creating a proton gradient which creates potential energy

• Series of Fe-S centers accepts electrons

Complex 2

• Succinate dehydrogenase

• Not pumping protons 

• CoQ accepts electrons from complex two and reduced to QH2

• FAD has less energy than NADH

Complex 3

• QH2 oxidized

• Proton pumping

• Iron sulfur centers passes around electrons

• Cytochrome C is mobile and is an electron acceptor/carrier

• Cytochromes present b and c

• Cytochrome C soluble peripheral protein of intermembrane space

Complex 4

• Cytochrome C in reduced form transfers electrons into complex four

• Large dimeric 

• 3 subunits

• Passes electrons from a series of Hemes, O2 accepts electrons, makes water

• Pumps protons