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Ch 6
Cellular Respiration
Energy for life
ECOSYSTEM
Photosynthesis
in chloroplasts
Glucose
CO
+
2
+
H2O
O2
Cellular respiration
in mitochondria
ATP
(for cellular work)
Heat energy
Breathing vs Cellular Respiration
• Breathing- gas exchange
• Cellular respiration- aerobic harvesting of
energy from food molecules by cells
Cellular Respiration
• Energy stored in ATP
C6H12O6
Glucose
+ 6
O2
Oxygen
6 CO2
Carbon
dioxide
+ 6
H2O
Water
+
ATPs
Energy
Cell Respiration
Redox
• Oxidation- loss of e• Reduction- addition of e-
Loss of hydrogen atoms
(oxidation)
C6H12O6
+ 6 O2
6 CO2 + 6 H2O + Energy
(ATP)
Gain of hydrogen atoms
(reduction)
Glucose Oxidation
• Significant in oxidation f Glucose
– Dehydrogenase
– NAD+--coenzyme, electron carrier molecule
• Becomes NADH
• ***FADH
Oxidation
Dehydrogenase
NAD+ + 2 H
Reduction
2 H+ + 2 e–
NADH+ H+
(carries
2 electrons)
Electron Transport Chain
• NADH transfer eto ETC
• Redox reactions as NAD
e- travel through +
H
chain
• O2 final e- acceptor
• Energy released at
each step
NADH
ATP
+
2e–
Controlled
release of
energy for
synthesis
of ATP
+
2e–
H+
H2O
1

2
O2
Cell Respiration
Glycolysis
• Splits sugar
• Breaks Glucose from 6- C
sugar into two 3- C sugars
• Yields 2 pyruvate
molecules
– Net gain of 2 ATP, 2
NADH, 2 H2O
Glucose
2 ADP
2 NAD+
+
2 P
2 NADH
2 ATP
+
2 H+
2 Pyruvate
Glycolysis
• Substrate-level phosphorylation
– Transfer of P from substrate to ADP to become
ATP
• Energy banked in ATP and NADH
Enzyme
P
Enzyme
ADP
+
P
Substrate
ATP
P
Product
Glycolysis
• 3 “phases”
– Energy consuming
– Glucose split
– Energy producing
• G3P is significant intermediate
– Glyceraldehyde-3-phosphate
Fig. 6-7c
ENERGY INVESTMENT
PHASE
Glucose
ATP
Steps 1 – 3 A fuel molecule is energized,
using ATP.
Step
1
ADP
P
Glucose-6-phosphate
P
Fructose-6-phosphate
P
Fructose-1,6-bisphosphate
2
ATP
3
ADP
P
Step 4 A six-carbon intermediate splits
Into two three-carbon intermediates.
4
P
Step 5 A redox reaction
generates NADH.
Glyceraldehyde-3-phosphate
(G3P)
P
NAD+
NAD+
5
P
NADH
5
NADH
+ H+
ENERGY PAYOFF PHASE
P
+ H+
P
P
ADP
P
P 1,3-Bisphosphoglycerate
ADP
6
6
ATP
ATP
P
P 3-Phosphoglycerate
7
Steps 6 – 9 ATP and pyruvate
are produced.
7
P
P
2-Phosphoglycerate
8
H2 O
P
P
ADP
Phosphoenolpyruvate
(PEP)
ADP
9
ATP
8
H2 O
9
ATP
Pyruvate
Pyruvate
•
•
Cannot enter Citric Acid Cycle directly
3 reactions take place
1. Carboxyl group removed, given off as CO2
2. Remaining 2-C compound oxidized, NAD+
reduced (2 NADH formed)
3. Coenzyme A combines with 2-C compound to
form Acetyl Coenzyme A
Formation of Acetyl CoA
NADH + H+
NAD+
2
CoA
Pyruvate
Acetyl coenzyme A
1
3
CO2
Coenzyme A
Cell Respiration
Krebs Cycle
• AKA the Citric Acid Cycle
– Mitochondrial matrix
• Starts with Acetyl Coenzyme A
– Only Acetyl part joins cycle (2-C)
– Coenzyme A is recycled
• Nets 2 CO2, 3 NADH, 1 FADH2 and 1 ATP per
turn
– 1 glucose=2 pyruvate=2 Acelty CoA=2 turns Kreb
Cycle
Krebs Cycle
Cell Respiration
Oxidative Phosphorylation
• Stage where most ATP is produced
– Membrane of mitochondria
• 2 parts
– ETC
– Chemiosmosis
• ETC creates gradient
• Chemiosmosis uses gradient to generate ATP
Oxidative Phosphorylation
Intermembrane
space
Protein
complex
of electron
carriers
H+
H+
H+
H+
H+
H+
H+
Electron
carrier
H+
H+
ATP
synthase
Inner
mitochondrial
membrane
FADH2
Electron
flow
NADH
Mitochondrial
matrix
FAD
NAD+
H+
1

2
O2 + 2 H+
H+
H+
H2O
Electron Transport Chain
OXIDATIVE PHOSPHORYLATION
ADP + P
ATP
H+
Chemiosmosis
Overall
• Start with 1 glucose molecule
– Split into 2 pyruvate in Glycolysis
– Yields 2 ATP, 2 NADH, 2 H20
• 2 Pyruvate converted to 2 Acetyl CoA
– Yields 2 NADH
• Acetyl CoA enters Kreb Cycle
– Yields 2 ATP, 6 NADH, 2 FADH (per glucose)
• Oxidative Phosphorylation
– Yields 34 ATP
ATP yield
Electron shuttle
across membrane
Cytoplasm
2
Mitochondrion
2
NADH
NADH
(or 2 FADH2)
2
6
NADH
GLYCOLYSIS
2
Pyruvate
Glucose
2 Acetyl
CoA
CITRIC ACID
CYCLE
+ 2 ATP
+ 2 ATP
by substrate-level
phosphorylation
by substrate-level
phosphorylation
Maximum per glucose:
About
38 ATP
NADH
2
FADH2
OXIDATIVE
PHOSPHORYLATION
(Electron Transport
and Chemiosmosis)
+ about 34 ATP
by oxidative phosphorylation
Stopping the chain
• Poisons can act during Oxidative
Phosphorylation
– Rotenone
• Blocks ETC by binding to e- carrier molecules
– Cyanide, CO
• Blocks ETC by binding to e- carrier molecules
• O2 cannot accept e-
– Oligomycin
• Blocks ATP synthase
– Uncouplers (DNP)
• Creates leaky membrane
Fig. 6-11
Cyanide,
carbon monoxide
Rotenone
Oligomycin
H+
H+
H+
ATP
synthase
H+
H+ H+ H+
DNP
FADH2
FAD
1

2
NAD+
NADH
O2 + 2 H+
H+
H+
H2O
ADP + P
ATP
H+
Electron Transport Chain
Chemiosmosis
Alternate Pathways
• Aerobic v Anaerobic
• Obligate anaerobes
• Facultative anaerobes
Fermentation
• Anaerobic
– Allows cells to generate ATP in absence of O2
•
•
•
•
Regenerates NAD+ to break down glucose
Only yields 2 ATP
Lactic Acid in animal muscles
Ethanol in bacteria and yeast
Fermentation
Glucose
+ 2
2
P
ATP
2 NAD+
2 ADP
+ 2 P
2 NADH
2
ATP
2 Pyruvate
2 NAD+
GLYCOLYSIS
2 ADP
GLYCOLYSIS
Glucose
2 NADH
2 Pyruvate
2 NADH
NADH
2
2 CO2
released
NAD+
2 NAD+
2
2 Lactate
2 Ethanol
We eat more than just glucose
• Different foods enter the process at different
stages
• Typically broken down before entering cycles
Fig. 6-15
Food, such as
peanuts
Carbohydrates
Fats
Glycerol
Sugars
Proteins
Fatty acids
Amino acids
Amino
groups
Glucose
G3P
Pyruvate
GLYCOLYSIS
Acetyl
CoA
ATP
CITRIC
ACID
CYCLE
OXIDATIVE
PHOSPHORYLATION
(Electron Transport
and Chemiosmosis)
• ETC
• http://www.youtube.com/watch?v=Idy2XAlZIVA&fea
ture=related
• http://www.youtube.com/watch?v=xbJ0nbzt5Kw
• Glycolysis
• http://www.youtube.com/watch?v=x-stLxqPt6E
• Kreb
• http://www.youtube.com/watch?v=aCypoN3X7KQ&f
eature=related
• Overview
• http://www.youtube.com/watch?v=iXmw3fR8fh0
• Fermentation
• http://www.youtube.com/watch?v=y_k8xLrBUfg