Cellular Respiration Part IV:
Oxidative Phosphorylation
Curriculum Framework
• 2A2 Organisms capture and store free energy
for use in biological processes.
g. The electron transport chain captures
free energy from electrons in a series of
coupled reactions that establish an
electrochemical gradient across
membranes.
2
Figure 9.6-3
Electrons
carried
via NADH
Glycolysis
Glucose
Pyruvate
Electrons carried
via NADH and
FADH2
Citric
acid
cycle
Pyruvate
oxidation
Acetyl CoA
CYTOSOL
Oxidative
phosphorylation:
electron transport
and
chemiosmosis
MITOCHONDRION
ATP
ATP
ATP
Substrate-level
phosphorylation
Substrate-level
phosphorylation
Oxidative
phosphorylation
Curriculum Framework
2A2g2. In cellular respiration, electrons delivered by
Oxidative
NADH
and FADH2 Phosphorylation:
are passed to a series of electron
acceptors as they move toward the terminal
Electron
Transport
and
electron
acceptor,
oxygen.
Chemiosmosis
Curriculum Framework
2A2g3. The passage of electrons is accompanied
by the formation of a proton gradient across the
inner
mitochondrial
membrane or the thylakoid
t and
Chemiosmosis
membrane of chloroplasts, with the membrane
separating a region of high proton concentration
from a region of low proton concentration. In
prokaryotes, the passage of electrons is
accompanied by the outward movement of
protons across the plasma membrane.
Electron transport chain
Outer
mitochondrial
membrane
Inner
mitochondrial
membrane
Electron carrier
(NADH)
Electrons
Oxygen
Hydrogen ions
Electrons
Water
Hydrogen ions
Area of high
hydrogen ion
concentration
Inner
mitochondrial
membrane
ATP
ATP synthase
Outer
mitochondrial
membrane
Inner
mitochondrial
membrane
Chemiosmosis:
The Energy-Coupling Mechanism
• Electron transfer in the electron transport chain
causes proteins to pump H+ from the
mitochondrial matrix to the intermembrane space
• H+ then moves back across the membrane,
passing through the enzyme, ATP synthase
• ATP synthase uses the exergonic flow of H+ to
drive phosphorylation of ATP
• This is an example of chemiosmosis, the use of
energy in a H+ gradient to drive cellular work
Figure 9.14
INTERMEMBRANE SPACE
H
Stator
Rotor
Internal
rod
Catalytic
knob
ADP
+
Pi
ATP
MITOCHONDRIAL MATRIX
Figure 9.15
H
H

H
Protein
complex
of electron
carriers
Cyt c
Q
I
IV
III
II
FADH2 FAD
NADH
H
2 H + 1/2O2
ATP
synthase
H2O
NAD
ADP  P i
(carrying electrons
from food)
ATP
H
1 Electron transport chain
Oxidative phosphorylation
2 Chemiosmosis
• The energy stored in a H+ gradient across a
membrane couples the redox reactions of the
electron transport chain to ATP synthesis
• The H+ gradient is responsible for establishing
a proton-motive force, emphasizing its
capacity to do work
Mitochondrial Membrane
• Name and describe three structural features
that make the mitochondrial membrane
effective at the process of energy transfer.
15
ATP Production by Cellular Respiration
Arrange these in order of energy transfer through
chemiosmosis:
•
•
•
•
•
electron transport chain
Glucose
proton-motive force
NADH
ATP
Figure 9.16
Electron shuttles
span membrane
2 NADH
Glycolysis
2 Pyruvate
Glucose
MITOCHONDRION
2 NADH
or
2 FADH2
2 NADH
Pyruvate oxidation
2 Acetyl CoA
 2 ATP
Maximum per glucose:
CYTOSOL
6 NADH
2 FADH2
Citric
acid
cycle
Oxidative
phosphorylation:
electron transport
and
chemiosmosis
 2 ATP
 about 26 or 28 ATP
About
30 or 32 ATP