chapter 8 harvesting energy: glycolysis and cellular
TRANSCRIPT
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Chapter 8
Harvesting Energy: Glycolysis and Cellular Respiration
Chapter 8: Glycolysis and Cellular Respiration
What is Glucose Metabolism?
Photosynthesis:
= 6 CO2
Carbon
dioxide
+ 6 H2O
Water
C6H12O6
Glucose
+ 6 O2
Oxygen
Glucose Metabolism:
+ Energy
Chemical (40%)
Heat (60%)
Answer: The breakdown of glucose to release energy from
chemical bonds
+ Light
Energy6 CO2
Carbon
dioxide
+ 6 H2O
Water
= C6H12O6
Glucose
+ 6 O2
Oxygen
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Major Steps of Glucose Metabolism
Glucose
1) Glycolysis (2 ATP)
PyruvateNo oxygen present
(Anaerobic)
2) Fermentation
Ethanol
Lactate
Oxygen present
(Aerobic)
3) Cellular Respiration(36 ATP)
Carbon Dioxide
Water
Cytoplasm
Mitochondria
Chapter 8: Glycolysis and Cellular Respiration
Glucose Metabolism:
Chapter 8: Glycolysis and Cellular Respiration
Figure 8.1 – Audesirk2 & Byers
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1) Glycolysis (Greek: “To break down a sweet”)
• Ancient biochemical pathway (all organisms do it...)
• Occurs in cytoplasm; does not require oxygen
Major Steps:
A) Glucose Activation: Initiation of the reaction (takes energy…)
2 ATP 2 ADP
(Activation Energy)C C C CCC
Glucose
Chapter 8: Glycolysis and Cellular Respiration
CCC x 2
P
Glyceraldehyde
3-phosphate
(G3P)
x 2
1) Glycolysis (Greek: “To break down a sweet”)
• Ancient biochemical pathway (all organisms do it...)
• Occurs in cytoplasm; does not require oxygen
Major Steps:
A) Glucose Activation: Initiation of the reaction (takes energy…)
B) Energy Harvesting: Completion of the reaction (… to make energy)
Chapter 8: Glycolysis and Cellular Respiration
4 ADP 4 ATP
CCC x 2
P
Glyceraldehyde
3-phosphate
(G3P)
2 NAD+ 2 NADH
CCC x 2
Pyruvate
4
Net ATP Gain = 2 ATP
Chapter 8: Glycolysis and Cellular Respiration
Glycolysis in Review:
Figure 8.2 – Audesirk2 & Byers
Major Steps of Glucose Metabolism
Glucose
1) Glycolysis (2 ATP)
PyruvateNo oxygen present
(Anaerobic)
2) Fermentation
Ethanol
Lactate
Oxygen present
(Aerobic)
3) Cellular Respiration(36 ATP)
Carbon Dioxide
Water
Chapter 8: Glycolysis and Cellular Respiration
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2) Fermentation: Process for regenerating NAD+ for glycolysis
• Crucial for organisms that live where O2 is rare (e.g., intestines / soils / bogs)
A) Lactate Fermentation: Pyruvate converted to lactate (lactic acid)
CCC x 2
Lactate
CCC x 2
Pyruvate
2 NADH 2 NAD+ (Back to glycolysis)
Chapter 8: Glycolysis and Cellular Respiration
Types of Fermentation:
Does NOT
produce ATP!
Lactate Fermentation:
Chapter 8: Glycolysis and Cellular Respiration
Figure 8.3 / 8.4 – Audesirk2 & Byers
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2) Fermentation: Process for regenerating NAD+ for glycolysis
• Crucial for organisms that live where O2 is rare (e.g., intestines / soils / bogs)
A) Lactate Fermentation: Pyruvate converted to lactate (lactic acid)
B) Alcoholic Fermentation: Pyruvate converted to ethanol and CO2
Chapter 8: Glycolysis and Cellular Respiration
Types of Fermentation:
Does NOT
produce ATP!
CCC x 2
Ethanol
x 2
Carbon
Dioxide
+CCC x 2
Pyruvate
2 NADH 2 NAD+ (Back to glycolysis)
Alcoholic Fermentation:
Chapter 8: Glycolysis and Cellular Respiration
Figure 8.3 / 8.5 – Audesirk2 & Byers
Yeast
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Major Steps of Glucose Metabolism
Glucose
1) Glycolysis (2 ATP)
PyruvateNo oxygen present
(Anaerobic)
2) Fermentation
Ethanol
Lactate
Oxygen present
(Aerobic)
3) Cellular Respiration(36 ATP)
Carbon Dioxide
Water
Chapter 8: Glycolysis and Cellular Respiration
3) Cellular Respiration: Series of reactions that produces ATP
• Occurs in mitochondria / requires oxygen
Chapter 8: Glycolysis and Cellular Respiration
= CO2
Carbon
Dioxide
+ H2O
Water
Pyruvate + O2
Oxygen
+ ATP
Chemical
Energy
• Mitochondria have two membranes
• Outer membrane (smooth)
• Inner membrane (folded – cristae)
• Mitochondria have two compartments
• Intermembrane compartment
• Matrix
Recall from Chapter 4:
Figure 4.17 – Audesirk2 & Byers
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3) Cellular Respiration: Series of reactions that produces ATP
• Occurs in mitochondria / requires oxygen
Chapter 8: Glycolysis and Cellular Respiration
Sequence of Events:
A) Pyruvate diffuses into mitochondrial matrix
• Travels down concentration gradient (via pores)
B) Pyruvate converted to acetyl CoA:
CC - CoA x 2
Acetyl CoANAD+ NADH
Coenzyme A CO2
C( x 2)
CCC x 2
Pyruvate
3) Cellular Respiration: Series of reactions that produces ATP
• Occurs in mitochondria / requires oxygen
Chapter 8: Glycolysis and Cellular Respiration
Sequence of Events:
C) Krebs Cycle:CC - CoA (x 2)
Acetyl CoA
Krebs
Cycle
2 CO2C( )C(x 2)
FAD
FADH2
(x 2)
3 NAD+
3 NADH
(x 2)
ADP
ATP
(x 2)
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DO NOT
COPY!
Chapter 8: Glycolysis and Cellular Respiration
The True Story:
The Krebs Cycle is also
called the Citric Acid Cycle
Figure E8.3 – Audesirk2 & Byers
Review of Cellular Respiration:
Chapter 8: Glycolysis and Cellular Respiration
Energy Checklist (per glucose):
1) 2 ATP
2) 10 Electron-carrier Molecules
• NADH (8)
• FADH2 (2)
Figure 8.7 – Audesirk2 & Byers
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3) Cellular Respiration: Series of reactions that produces ATP
• Occurs in mitochondria / requires oxygen
Chapter 8: Glycolysis and Cellular Respiration
Sequence of Events:
D) Electron Transport Chain:
• Location where electron-carrier molecules unload their electrons
Located in the inner
mitochondrial membrane
Outer
Membrane
Inner
Membrane
Intermembrane Compartment
Matrix
ETC
NAD+
FAD
NADH
FADH2
2e-
H+H+H+
1/2 O2 + 2 H+ H2O
2e-
2e-
Electron Transport Chain: Cyanide
Chapter 8: Glycolysis and Cellular Respiration
Similar to Figure 8.8 – Audesirk2 & Byers
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3) Cellular Respiration: Series of reactions that produces ATP
• Occurs in mitochondria / requires oxygen
Chapter 8: Glycolysis and Cellular Respiration
Sequence of Events:
E) Chemiosmosis:
• Utilizes energy stored in H+ gradient to generate ATP
Located in the inner
mitochondrial membrane
H+
H+H+ H+
H+
H+
H+
H+
H+
H+H+
ATPADP
32 ATP
Outer
Membrane
Inner
Membrane
Intermembrane Compartment
Matrix
ETC
H+ H+ H+
H+ ion
channel
H+
(See “A Closer Look - Chemiosmosis: Chloroplasts – Pg. 124)
ATP diffuses out of mitochondria
to provide energy for cellular processes
Chapter 8: Glycolysis and Cellular Respiration
Chemiosmosis:
Figure 8.8 – Audesirk2 & Byers
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Final Tally of Energy
Production:
One Molecule of Glucose
Yields 36 - 38 ATP
Yippee!
Chapter 8: Glycolysis and Cellular Respiration
Figure 8.10 – Audesirk2 & Byers
Multiple Biomolecules Yield Energy:
(See Health Watch - Pg. 144)
Fats:
• Glycerol Enters glycolysis
• Fatty Acids Enters Krebs cycle
Reversal true as well:
Glucose Fats
Chapter 8: Glycolysis and Cellular Respiration
Proteins:
• Enter at multiple stages
Figure E8.4 – Audesirk2 & Byers