2. Oxidative Phosphorylation
This occurs in the inner membranes of the mitochondria
enzymes and protein carrier molecules embedded
folded into cristae to increase the surface area
3. NAD reduced and FAD reduced are passed to ETC
The Hydrogen atom is split into
a proton (H+) and
an electron (e-)
4. The proton remains in
solution
The molecule that splits
hydrogen moves the
proton into the inter-
membrane space
The proton will later be
used to reduce oxygen
5. The electron is
transferred to various
electron carriers along a
biological electron
transport chain
At certain points ATP is
made by phosphorylation
– during chemiosmosis
Oxygen is finally reduced
to water
6.
7. Biological electron transport
This is a series of linked oxidation and
reduction, or Redox, reactions
a donor and an acceptor of electrons
The acceptor gains an electron and
becomes reduced
The donor looses an electron and
becomes oxidized
Fe2+ + Cu2+ Fe 3+ + Cu+
8. Energy is lost as the electron is
passed along the chain
usually as heat
At certain points there is enough
energy to make ATP
This is done by a process called
Chemiosmosis
9. In the first step NADreduced
donates the hydrogen to a
hydrogen carrier
The first hydrogen carrier is
now in the reduced state
10. The hydrogen is then passed to a
second hydrogen carrier molecule
This is now reduced
The first carrier is oxidised
It can now pick up more hydrogen
11. It is at this point that FAD can first
donate hydrogen
If FAD is being used the process
begins here
12. The hydrogen is broken into a proton and an
electron
The proton is released into the inter-
membrane space because of the structure of
the carrier molecule
This will make a proton gradient across the
inner membrane
14. The electron is passed to a second
electron carrier then to Cytochrome
oxidase – which is now reduced
15. The final electron acceptor is oxygen
Two electrons combine with a 2
protons to form 2 hydrogens
These are picked up by oxygen,
forming water
16. The final step in oxidative
phosphorylation involves cytochrome
oxidase reducing oxygen to water.
This step can be inhibited using
Potassium Cyanide or Carbon monoxide
These are known as respiratory
inhibitors
they can be used experimentally to show
the effects of blocking respiration
(energy release) on a process
17. The transfer of electrons makes energy available
Some is lost as heat
But at some points there is enough energy
released to produce ATP
Potentially each NADreduced can generate 3 ATP molecules
And each NADreduced can generate 2 ATP molecules
18.
19. In reality 25% of the energy made is used in
transporting ATP out of the mitochondria
therefore
For each NAD reduced there are 2.5
ATP made
For each FAD reduced there are 1.5
ATP made
23. the most accepted explanation for ATP
synthesis during the electron transport
chain
Note that ATP formed in glycolysis and
the Krebs cycle uses Chemical
Potential energy from the bonds
24. Energy from the ETC is used
to pump hydrogen ions
from the mitochondrial
matrix
to the space between the
membranes of the envelope
25. This occurs because of the orientation of the proteins that
pick up and then loose the hydrogen ions
they will always transfer the ions to one side of the
membrane
26. There are “stalked particles” that cross the
inner membrane and act as both channels
for the H+ ions to diffuse down their
gradient,
And as ATPsynthase molecules
27. For 3 H+
ions moving through the ATPsynthase one
ADP is phosphorylated to ATP
