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Chapter 8: Harvesting Energy: Glycolysis and Cellular Respiration
Chapter 8: Glycolysis and Cellular Respiration
What is Glucose Metabolism?
Answer: The breakdown of glucose to release energy from its chemical bonds
6 CO 2 + (^) EnergyLight Carbon Dioxide
= C 6 H 12 O (^6) Glucose
Photosynthesis:
= 6 CO (^2) Carbon Dioxide
C 6 H 12 O (^6) Glucose
Glucose Metabolism:
- Energy Chemical (40%) Heat (60%)
Major Steps of Glucose Metabolism
Glucose
- Glycolysis (2 ATP)
Pyruvate (^) No oxygen present (Anaerobic)
- Fermentation
Ethanol Lactate
Oxygen present (Aerobic)
(36 ATP) 3) Cellular Respiration
Carbon Dioxide Water
Cytoplasm
Mitochondria
Chapter 8: Glycolysis and Cellular Respiration Major Steps in Glucose Metabolism:
(Figure 8.1)
- Glycolysis (Greek: “To break down a sweet”)
- Ancient biochemical pathway (all organisms do it...)
- Occurs in the cytoplasm; Does not require oxygen
Two Major Components: A) Glucose Activation: Initiate the reaction (takes energy)
2 ATP 2 ADP
(Activation Energy)
C C C CCC
Glucose
C CC x 2 P Glyceraldehyde 3-phosphate (G3P)
Chapter 8: Glycolysis and Cellular Respiration
- Glycolysis (Greek: “To break down a sweet”)
- Ancient biochemical pathway (all organisms do it...)
- Occurs in the cytoplasm; Does not require oxygen
Two Major Components: A) Glucose Activation: Initiate the reaction (takes energy) B) Energy Harvesting: Complete the reaction (makes energy)
4 ADP 4 ATP C CC x 2 P Glyceraldehyde 3-phosphate
2 NAD +^ 2 NADH
C CC x 2 Pyruvate
Chapter 8: Glycolysis and Cellular Respiration
Glycolysis in Review:
Net ATP Gain = 2 ATP
(similar to Figure 8.2)
Chapter 8: Glycolysis and Cellular Respiration
Major Steps of Glucose Metabolism
Glucose
- Glycolysis (2 ATP)
Pyruvate No oxygen present (Anaerobic)
- Fermentation
Ethanol Lactate
Oxygen present (Aerobic)
(36 ATP) 3) Cellular Respiration
Carbon Dioxide Water
Chapter 8: Glycolysis and Cellular Respiration
- Fermentation: Process for regenerating NAD+^ for glycolysis
- Occurs in organisms which live where oxygen is rare
- Intestines / stomach; soils / sediments / bogs Two Types of Fermentation: A) Lactate Fermentation: Pyruvate converted to lactate (lactic acid)
C CC x 2 Lactate
C CC x 2 Pyruvate
2 NADH 2 NAD^ +^ (Back to glycolysis)
Chapter 8: Glycolysis and Cellular Respiration Lactate Fermentation:
Chapter 8: Glycolysis and Cellular Respiration
- Fermentation: Process for regenerating NAD+^ for glycolysis
- Occurs in organisms which live where oxygen is rare
- Intestines / stomach; soils / sediments / bogs Two Types of Fermentation: A) Lactate Fermentation: Pyruvate converted to lactate (lactic acid) B) Alcoholic Fermentation: Pyruvate converted to ethanol and CO (^2)
C CC x 2 Pyruvate
2 NADH 2 NAD^ +^ (Back to glycolysis) C C x 2 C Ethanol
x 2 Carbon Dioxide
Chapter 8: Glycolysis and Cellular Respiration
A) Formation of Acetyl CoA:
- Pyruvate diffuses into mitochondrial matrix
- Down concentration gradient (via pores)
C C- CoA x 2 NAD +^ NADH Acetyl CoA
Coenzyme A CO 2
( C)
- Cellular Respiration - Sequence of Events:
C CC x 2 Pyruvate
Chapter 8: Glycolysis and Cellular Respiration
- Cellular Respiration - Sequence of Events: B) Krebs Cycle (Citric Acid Cycle) :
C C- CoA^ (x 2) Acetyl CoA
Krebs Cycle
( C C )2 CO (^2) (x 2)
FAD
FADH 2
(x 2)
3 NAD+
3 NADH
(x 2)
ADP
ATP (x 2)
Chapter 8: Glycolysis and Cellular Respiration
The True Story:
DO NOT COPY!
Chapter 8: Glycolysis and Cellular Respiration Review:
(Figure 8.5)
Chapter 8: Glycolysis and Cellular Respiration
What energy molecules have we produced so far:
- 2 ATP (from glycolysis)
- 2 ATP (from Krebs cycle)
- Multiple Electron-carrier Molecules:
- 2 NADH (from glycolysis)
- 8 NADH (from Krebs cycle)
- 2 FADH 2 (from Krebs cycle)
- Cellular Respiration - Energy Checklist (Table 8.1):
Chapter 8: Glycolysis and Cellular Respiration
C) Electron Transport System
3) Cellular Respiration - Sequence of Events :
- Place where electron-carrier molecules unload their electrons
- Located in inner mitochondrial membrane Outer Membrane
Inner Membrane
Intermembrane Compartment
Matrix
ETS
NAD+ FAD
NADH FADH 2
2e-
H + H + H +
1/2 O 2 + 2 H+^ H 2 O
Chapter 8: Glycolysis and Cellular Respiration
Electron Transport Chain:
(Figure 8.6) cyanide
Chapter 8: Glycolysis and Cellular Respiration Sequence of Events in Cellular Respiration:
- Chemiosmosis:
- Captures energy stored in hydrogen ion gradient and produces ATP
- Located in inner mitochondrial membrane Outer Membrane
Inner Membrane
Intermembrane Compartment
Matrix
ETS
H+^ H+^ H+^ H
H+^ H+ H+
H+ H+
H+ H+
H+ H+ H+
H+ ion channel
H+
ADP ATP 32 ATP
Chapter 8: Glycolysis and Cellular Respiration
(See “A Closer Look - Chemiosmosis: Pg. 142)
Chemiosmosis:
- ATP diffuses out of mitochondria to provide energy for cellular processes
Chapter 8: Glycolysis and Cellular Respiration Final Tally of Energy Production:
(Figure 8.1)
One Molecule of Glucose Yields 36 - 38 ATP
Yippee!
How Various Biomolecules Yield Energy:
(See Health Watch - Pg. 136)
Fats:
- Glycerol → glycolysis
- Fatty Acids → Krebs cycle Proteins:
- Enter at multiple stages
Reversal true as well: Glucose → Fats
