CELLULAR RESPIRATION!
Some challenges…
• ATP is unstable and is not stored
A Tour of a Mitochondrion:
REDOX REACTIONS
Oxidation =
Reduction =
BIG PICTURE
Time to Make ATP!
The Stages of Cellular Respiration:
1. Glycolysis
2. Pyruvate Processing
3. The Citric acid (Krebs) cycle
4. Oxidative phosphorylation: ETC and chemiosmosis
Glycolysis
Glycolysis
• Substrate-level
Phosphorylation
Process
Location
Inputs
Outputs
Net ATP
Pyruvate Processing
Pyruvate Processing
• Pyruvate Processing
Process
Location
Inputs
Outputs
Net ATP
The Citric Acid (Krebs) Cycle
The Citric Acid (Krebs) Cycle
Overview:
• Generates 1 ATP/turn
• Most of energy
transferred to electron
carriers NAD+ and FAD
(reduced)
• Further oxidation of
acetyl CoA into CO2
•
Substrate-level
Phosphorylation

Process
Location
Inputs
Outputs
Net ATP
The Electron Transport Chain
The Electron Transport Chain (ETC)
Overview:
• Electron carriers (NADH and FADH2)
“drop off” their electrons at the ETC!
• The electrons are passed to a series of
increasingly electronegative electron
acceptors until they move to the terminal
electron acceptor…OXYGEN!
Fig. 9-13
NADH
50
2 e–
NAD+
FADH2
2 e–
40

FMN
FAD
Multiprotein
complexes
FAD
Fe•S 
Fe•S
Q

Cyt b
30
Fe•S
Cyt c1
I
V
Cyt c
Cyt a
Cyt a3
20
10
0
2 e–
(from NADH
or FADH2)
2 H+ + 1/2
O2
H2O
Fig. 9-16
The Electron Transport Chain (ETC)
H+
H+
H+
H+
Protein complex
of electron
carriers
Cyt c
V
Q



FADH2
NADH
ATP
synthase
FAD
2 H+ + 1/2O2
NAD+
H2O
ADP + P i
(carrying electrons
from food)
ATP
H+
1 Electron transport chain
Oxidative phosphorylation
2 Chemiosmosis
Fig. 9-14
INTERMEMBRANE SPACE
H+
Stator
Rotor
Internal
rod
Catalytic
knob
ADP
+
P
i
ATP
MITOCHONDRIAL MATRIX
Process
Location
Inputs
Outputs
Net ATP
Fig. 9-17
ATP Totals ?
Electron shuttles
span membrane
CYTOSOL
2 NADH
6 NADH
2 NADH
Glycolysis
2
Pyruvate
Glucose
MITOCHONDRION
2 NADH
or
2 FADH2
2
Acetyl
CoA
+ 2 ATP
Maximum per glucose:
2 FADH2
Citric
acid
cycle
Oxidative
phosphorylation:
electron transport
and
chemiosmosis
+ 2 ATP
+ about 32 or 34 ATP
About
36 or 38 ATP
NET EQUATION FOR
CELLULAR RESPIRATION:
Let’s see it in motion…
MODELING CELLULAR
RESPIRATION
1. Glycolysis
2. Pyruvate Processing
3. The Citric acid (Krebs) cycle
4. Oxidative phosphorylation: ETC and chemiosmosis