Fig. 9.1 Respiration. Cellular Energy Harvest: an Overview Stages of Aerobic Cellular Respiration...
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Transcript of Fig. 9.1 Respiration. Cellular Energy Harvest: an Overview Stages of Aerobic Cellular Respiration...
Fig. 9.1
Respiration
• Cellular Energy Harvest: an Overview
• Stages of Aerobic Cellular Respiration– Glycolysis– Oxidation of Pyruvate– Krebs Cycle– Electron Transport Chain
• Anaerobic Respiration and Fermentation
• Catabolism of Protein and Fat
Outline – Cellular Respiration
• Autotrophs – use inorganic sources of energy
• Photoautotrophs– harvest sunlight – convert radiant energy into chemical energy.
• Heterotrophs – use organic sources of energy– live off the energy produced by autotrophs.– extract energy from food catabolism
Energy to Drive Metabolism
Cellular Respiration
• How do cells harvest energy – cells break chemical bonds– shift electrons from molecule to molecule
• Where do the electrons go?– Aerobic respiration
• final electron acceptor is oxygen
– Anaerobic respiration • final electron acceptor is not oxygen• Fermentation - final electron acceptor is an
organic molecule
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Glucose molecules broken down to CO2
Glucose loses electrons (as hydrogen atoms) to oxygen
Cells tap energy from electrons
Cells bank energy in ATP
C6H12O6 6 O2 6 CO2 6 H2O
Loss of hydrogen atoms (oxidation)
Gain of hydrogen atoms (reduction)
Energy
(ATP)
Glucose
+ + +
Cellular Aerobic Respiration
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Oxidation - Dehydrogenase removes electrons from substrate
Reduction - Electrons in Hydrogen Transferred to NAD+
OH H O 2H
Reduction
Dehydrogenase (Enzyme)
(carries2 electrons)
NAD 2H
2H 2e
NADH H
Oxidation
+
+
+
+
Transferring Energy
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
H2O
NAD
NADH
ATP
H
H
Controlled release of energy for ATP
synthesis
Electron Transport
Chain
O2
2e
2e
1. NADH passes electrons to an electron transport chain
2. Energy is released as electrons “fall” and lose energy
Transferring Energy – Electron Transport Chain
Fig. 9.5 (TEArt)
Mitochondrion
Krebscycle
Glucose
Glycolysis
Pyruvate
Acetyl-CoA
ATP
ATP
ATP
NADH
NADH
NADH
FADH2
Electrontransport chain
H2O
CO2
NAD+ and FAD
Mitochondrial matrix
Inner mitochondrial membrane
Cytoplasm
Intermembranespace
e-
Pyruvateoxidation
CO2
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Aerobic Cellular Respiration – Overview
1. Glycolysis
2. Pyruvate oxidation
3. Krebs (Citric Acid) Cycle
4. Electron Transport Chain
Fig. 9.6 (TEArt)
Aerobic Respiration Stage 1: Glycolysis1 2 3
(Starting material)
6-carbon sugar diphosphate
6-carbon glucose
2
P P
6-carbon sugar diphosphate
P P
3-carbon sugarphosphate
P P P P
Priming reactions.
3-carbonpyruvate
2
NADH
ATP
ATP 2
NADH
ATP
Cleavage reactions. Energy-harvesting reactions.
3-carbon sugarphosphate
3-carbon sugarphosphate
3-carbon sugarphosphate
3-carbonpyruvate
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Fig. 9.7a (TEArt)
Pi
3
6
4,5
ADP
NAD+
Glucose
Glycolysis
Pyruvateoxidation
Krebscycle
Electron transportchain
Glucose
Hexokinase
Phosphoglucoseisomerase
Phosphofructokinase
Glyceraldehyde 3-phosphate (G3P)
Dihydroxyacetonephosphate
Glucose 6-phosphate
Fructose 6-phosphate
Fructose 1,6-bisphosphate
Isomerase
Glyceraldehyde3-phosphate
dehydrogenase
Aldolase
1,3-Bisphosphoglycerate(BPG)
1,3-Bisphosphoglycerate(BPG)
1. Priming
4–5. Six-carbon molecule split into 2 three-carbon moleculesone G3P & dhap which is converted to G3P
1
2
ATP
ADP
ATP
NADH
NAD+
NADH6. Oxidation followed byphosphorylation produces two NADH molecules andtwo molecules of BPG, each with one high-energyphosphate bond.
Pi
P O CH2
C O
CH2OH
P O
CH2 O P
O
CHOH
C
CH2 O P
O
CHOH
CH2 O PO
CH2OP
O
PO
CH2
H
CH2OHO
CH2 POO
CH2OH
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Glycolysis - Steps
2. Cleavage
1. Priming
3. Energy HarvestC
Fig. 9.7b (TEArt)
7
8
H2O9
10
ADP
ATP3-Phosphoglycerate
(3PG)3-Phosphoglycerate
(3PG)
2-Phosphoglycerate(2PG)
2-Phosphoglycerate(2PG)
Phosphoenolpyruvate(PEP)
Phosphoenolpyruvate(PEP)
Pyruvate
7. Removal of high-energy phosphate by two ADP molecules produces twoATP molecules and leaves two 3PG molecules.
Phosphoglyceratekinase
Phosphogly-ceromutase
Enolase
Pyruvate kinase
ADP
ATP
ADP
ATP
ADP
ATP
8–9. Removal of water yields two PEP molecules, each with a high-energy phosphate bond.
10. Removal of high-energyphosphate by two ADPmolecules produces twoATP molecules and twopyruvate molecules.
H2O
CH2OH
CH3
CH2
O-
O
C
PH
CHOH
O-
O-
O-
C
C
C
C
C
C
P
P
O
O
O
O
O
O
CH2
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Glycolysis - Steps3. Energy Harvest
3. Energy Harvest
Pyruvate
1,3-Bisphosphoglycerate(BPG)
Catabolic pathway with 3 major events 1. Priming2. Cleavage3. Energy Harvesting
Substrate-level phosphorylation
Nets two ATP molecules
Universal: All living organisms
Glycolysis - Summary
Aerobic Respiration Stage 2Oxidation of Pyruvate
1. Releases CO2 2. Produces NADH and acetyl Coenzyme A3. Acetyl CoA is transferred to the mitochondrion
Aerobic Respiration Stage 3: KREBS CYCLE
Mito
chon
drio
n
Krebs Cycle Summary
1. Location: Mitochondrial matrix
2. Loss of 2 CO2 = completion of pyruvate oxidation
3. ATP synthesis
4. Reduction of Coenzymes…for each turn of cycle: 3 NAD+ 3 NADH… or 6 for each glucose 1 FAD 1 FADH2 …or 2 for each glucose
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Mitochondrion Structure
OuterMembrane
InnerMembrane
Cristae
Matrix
Intermembrane Space
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
1.Electron Flow occurs in mitochondrial membrane
2.Protons are transported across the inner mitochondrial membrane
3.ATP is synthesized by Chemiosmosis
Intermembrane space
Inner mitochondrial membrane
Mitochondrial matrix
Protein complex Electron
carrier
NAD+
FAD
H2O ATPADP
ATP synthase
H+ H+ H+
H+
H+ H+
H+H+
H+
H+
H+
H+
H+
H+
P
O2
Electron Transport Chain Chemiosmosis
.
OXIDATIVE PHOSPHORYLATION
+ NADH
FADH2
H+ H+
Stage 4: Oxidative Phosphorylation
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
1. Occurs in the mitochondria
2. Uses the energy released by electrons to pump H+ across a membrane
3. Harnesses the energy of the H+ gradient through chemiosmosis, producing ATP
Stage 4: Oxidative Phosphorylation
Oxidation-Reduction and Aerobic Respiration
– With continuous Glycolysis • NADH Increases• NAD+ Decreases
– NADH must be recycled into NAD+
Recycling NADH
Fermentation: Recycling NADH
22
Summary: Respiration without oxygenSummary: Respiration without oxygen
1. Glycolysis produces a net of 2ATP 1. Glycolysis produces a net of 2ATP 2. Fermentation - 2. Fermentation - recycles NADH to NADrecycles NADH to NAD++
Lactic acid fermentationLactic acid fermentation
COCO22 and Ethanol fermentation and Ethanol fermentation
3. Anaerobic Respiration3. Anaerobic RespirationMethanogensMethanogens
COCO22 CH CH44
Sulfate-reducing BacteriaSulfate-reducing Bacteria
SOSO44 H H22SS
2
2 6 ATP
Pyruvate
Glucose
Acetyl-CoANADH
2 4 ATPNADH
2 ATP
2 ATP
6 18 ATPNADH
2 4 ATP
Total net ATP yield = 36 ATP
FADH2
Krebscycle
ATP Glycolysis
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Respiration Efficiency
Fig. 9.20 (TEArt)
Macromolecules
Cellbuilding blocks
Nucleicacids Proteins FatsPolysaccharides
Nucleotides Aminoacids
FattyacidsSugars
NH3 H2O CO2
Oxidativerespiration
Metabolic Waste
products
Pyruvate
Acetyl-CoA
Krebscycle
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Energy Sources for Cellular Respiration
END
Respiration