Page 91 - The Manga Guide to Biochemistry

When this occurs, a force called The concentration gradient
The concentration gradient is is a force which causes a

generated. This means that when the substance to naturally flow
concentration of the protons (H+) in from a higher concentration

the intermembrane space becomes to a lower concentration.
higher than in the matrix, the protons

try to flow toward the matrix.

the proton
passes
through
a gate.

intermembrane Cytochrome C ATP inner
space Complex III synthase membrane of
mitochondria
Complex I Co Q

Matrix

Complex IV

An electron transport chain in

satisfactory condition has a "gate"

through which the protons

can move into the matrix. Off you go, protons!

That gate is the ATP synthase.
When a proton passes through it,
one molecule of ATP is produced.

Therefore, 30 molecules of ATP are created from 10 molecules
of NADH (of which two molecules are produced via glycolysis),
and 4 molecules of ATP are created from 2 molecules of FADH2.

We get these numbers because the electrons originating from NADH
cause the "proton pumps" to work at all three locations, but the

electrons from FADH2 cause them to function at only two locations.

intermembrane Cytochrome C ATP inner
space synthase membrane of
Co Q Complex III Complex IV mitochondria
Complex I
We get it!
Matrix

bond
with
oxygen

And finally the electron and the

proton that were used bond with
oxygen (oxygen is required
here! ) to produce water.