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How Cells Release
Chemical Energy
Chapter 7
Overall Concept of Cellular Respiration
p.106a
Mitochondria Structure
Cristae or
ENERGY FLOW IN THE ECOSYSTEM
p.107d
W
h
o
c
a
n
R
e
s
p.108
Fig. 7-2, p.108
ATP
P
P
ATP
P
P
P
P
Stepped Art
Fig. 7-4, p.111
PGAL
NAD
Pi+
P
NADH NAD
P+i
P
1,3-bisphosphoglycerate
ADP
PGAL
ATP
ENERGY-RELEASING STEPS
OF GLYCOLYSIS
NADH
P
P
1,3-bisphosphoglycerate
ADP
ATP
substrate-level
phosphorylation
2 ATP invested
P
P
3-phosphoglycerate
3-phosphoglycerate
P
P
2-phosphoglycerate
H2
O
2-phosphoglycerate
H2
O
PEP
PEP
P
ATP
ADP
P
ADP
ATP
substrate-level
phosphorylation
2 ATP invested
pyruvate
pyruvate
to second set of reactions
Fig. 7-4b, p.111
GLYCOLYSIS REVIEW
•
•
•
•
•
In cytoplasm
Uses glucose, 2 ATP, 2 NAD
Makes 2 pyruvates, 4ATP, 2NADH
Net gain of ATP=2
Why 10 steps?
Acetyl-CoA
Formation
pyruvate
coenzyme A
(CO2)
NAD+
NADH
CoA
acetyl-CoA
Krebs Cycle
CoA
oxaloacetate
citrate
NAD+
NADH
NADH
NAD+
FADH2
FAD
NAD+
NADH
ATP
ADP +
phosphate
group
Fig. 7-7a, p.113
KREB’S CYCLE
Begins after the Intermediate step
Pyruvate
Acetyl CoA + CO2 + NADH
Acetyl CoA enters mitochondria matrix and reacts
with oxaloacetate
Citrate (aka citric
acid cycle)
A series of reactions will yield oxaloacetate again
(aka cycle)
Each pyruvate makes 3 NADH, 1FADH2, 1ATP, 2
CO2
How many per glucose?
Fig. 7-8b, p.114
Fig. 7-8c, p.114
ELECTRON TRANSPORT CHAIN
Mitochondrial membrane or cristae
Enzymes (Cytochromes) and ATP synthase on
membrane to shuttle electrons and protons
NADH, FADH2 gives up the H
H+ + e Electrons are passed through the membrane
proteins and the energy released is used to
transport the H to the outer membrane
The gradient established is the force needed to
allow the H to move back into the inner
membrane through ATP Synthase
The 4H + 4e + O2
H2O
What is the purpose of the oxygen?
HOW MANY ATP’S WAS THAT?
Each NADH can make 3ATP and FADH2 2ATP
____ATP From glycolysis
____NADH from Glycolysis x ___ =
____ATP From Kreb’s Cycle
____NADH from Kreb’s cycle x ___ =
_____FADH2 from KREb’s x _____ =
Total ATP ______
GLYCOLYSIS
2
ATP
energy input
4
C6H12O6
2
NAD+
2 NADH
2 ADP
ATP
energy output
2 pyruvate
2 ATP net
2 H2 O
ETHANOL
FORMATION
2 CO2
2 acetaldehyde
electrons, hydrogen
from NADH
2 ethanol
Stepped Art
Fig. 7-10, p.116
Fig. 7-10b, p.116
GLYCOLYSIS
C6H12O6
2
ATP
energy input
4
2
NAD+
2 NADH
2 ADP
ATP
energy output
2 pyruvate
2 ATP net
LACTATE
FORMATION
electrons, hydrogen
from NADH
2 lactate
Stepped Art
Fig. 7-11, p.117
Fig. 7-12a, p.117
WHAT IS THE PURPOSE OF ANAEROBIC
RESPIRATION?
• To continue making ATP even in the absence of
oxygen
• Can happen in glycolysis but soon ..
• NADH are used up
• Cannot be regenerted in ETC
• So has to be regenerated in the fermentation phase
of cell respiration
• Side effects – formation of ethanol, CO2 or lactate
FOOD
fats
fatty
acids
glycogen
glycerol
complex
carbohydrates
proteins
simple sugars
(e.g., glucose)
amino acids
NH3
glucose-6phosphate
urea
carbon
backbones
PGAL
2
glycolysis
ATP
4 ATP
(2 ATP net)
NADH
pyruvate
Acetyl-CoA
NADH
NADH,
FADH2
CO2
Krebs
Cycle
2 ATP
CO2
e–
ATP
ATP
ATP
H+
many ATP
fats
e– + oxygen
Fig. 7-13b, p.119
USES OF CELL RESPIRATION?
• ATP for cell work
• CO2 for photosynthesis
• Carbon skeletons for metabolism of
sugars, lipids, proteins, nucleic acids,
etc