Cellular Respiration
LEOxidized and GEReduced
H+ + e- -Therefore H atoms are removed electrons are also removed.
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energy
glucose
Reduction
Oxidation
6H2O6CO26O2C6H12O6 + ++
NAD+ and FAD
• Coenzyme of oxidation-reduction
• Electron Carriers
Cellular Respiration
• Glycolysis• Prep Phase (acetyl CoA)• Citric Acid Cycle (Kreb’s Cycle)• Electron Transport Chain (ETC)
An overview of cellular respiration (Layer 1)
Glycolysis
Glucose is broken down into two molecules of pyruvate
• Occurs in the cytoplasm• ATP is formed• Does not use oxygen
Glycolysis
Takes place in the cytoplasm
NAD+
What’s Happened so far?Glycolysis
O2
Used?
Glucose C now Product:
ATP
#
NADH
#
Glycolysis No 2 Pyruvates 2 2
pyruvate
pyruvate
glucose
Pyruvate as a key juncture in catabolism
If O2 is NOT available
• Fermentation, an anaerobic process, occurs in the cytoplasm. During fermentation, glucose is incompletely
metabolized to lactate, or to CO2 and alcohol (depending on the organism).
Fermentation Helps Produce Numerous Food Products
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Alcoholic Fermentation
Pyruvate + NADH
Ethanol + CO2 + NAD+
Vinegar
Lactic Acid Fermentation
Pyruvate + NADH
Lactic Acid + NAD+
If O2 is available
• Preparatory (prep) reaction, a aerobic process, occurs in the mitochondria.
• Occurs in mitochondria • Two carbons are released as CO2 (one from each
pyruvate)
14
What’s Happened so far?Krebs CycleOriginal C of glucose are
now
ATP NADH FADH2
Glycolysis 2 pyruvate 2 2
Acetyl CoA formation
2 CO2
& 2 acetyl CoA
2
Krebs Cycle
Total
glucose
An overview of cellular respiration (Layer 2)
Citric acid cycle
• Occurs in the matrix of the mitochondrion and produces NADH and FADH2
• Releases 4 carbons as CO2
• Produces 2 ATP molecules
17
What’s Happened so far?Krebs CycleOriginal C of glucose are
now
ATP NADH FADH2
Glycolysis 2 pyruvate 2 2
Acetyl CoA formation
2 CO2
& 2 acetyl CoA
2
Krebs Cycle 4 more CO2 2 6 2
Total 6 CO2 4 10 2
glucose
An overview of cellular respiration (Layer 3)
Mitochondrion Structure and Function
20© Dr. Donald Fawcett and Dr. Porter/Visuals Unlimited
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Cristae: locationof the electrontransportchain(ETC)
Matrix: locationof the prepreaction and thecitric acid cycleouter
membrane
innermembrane
intermembranespace
cristaematrix
45,0003X
Organization and Function of the Electron Transport Chain
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2
O212+
2
P
H+
e :
e :
Electron transport chain
high energyelectron
ATPchannelprotein
Intermembranespace
ATPsynthasecomplex
low energyelectron
cytochromeoxidase
cytochrome c
NADH-Qreductase
cytochromereductase
coenzyme Q
NADH
Matrix
FADH2 FAD+
NAD+
2
e-
2 ADP ATP32 ADPor 34
4 ADP
netATP
4 ATP total
2ADP
2ATP
Glycolysis
glucose pyruvatePreparatory reaction
Citric acidcycle
Electron transportchain and
chemiosmosis
NADH andFADH2
NADH
NADHe-
e-
e-e-
e-
e-
32 or34
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+H+
H+
H+
H+
ATP ADPH2O
H+
H+
H+
H+
H+
H+
H+
H+
H+H+H+
H+
H+
H+H+
H+
H+
ATPChemiosmosis
Electron Transport Chain (ETC)
• Extracts energy from NADH & FADH2
• Passes electrons from higher to lower energy states
• Produces 32 or 34 molecules of ATP
Max of 36 ATP per Glucose
Substrate-level ATP SynthesisCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
P
P
P
enzyme
ADP
ATP
BPG
3PG
Inside the Mitochondria
• Electron Transport Chain (ETC)• Location:
Eukaryotes: cristae of the mitochondria Aerobic prokaryotes: plasma membrane
• The electron transport chain Receives electrons from NADH & FADH2
Produces ATP by oxidative phosphorylation
• Oxygen serves as the final electron acceptor Oxygen combines with hydrogen ions to form water
*H+ is pumped against its gradient into the mitochondrial matrix
*Energy for active transport comes from electrons
Inside the Mitochondria
• Energy yield from glucose metabolism: Net yield per glucose:
• From glycolysis – 2 ATP
• From citric acid cycle – 2 ATP
• From electron transport chain – 32 or 34 ATP
Energy content:• Reactant (glucose) 686 kcal
• Energy yield (36 ATP) 263 kcal
• Efficiency is 39%
• The rest of the energy from glucose is lost as heat
Energy rich molecules: carbohydrates, fats, and proteins
Catabolism: Break down molecules usually exergonic (release energy)
Anabolism build molecules: usually endergonic (consume energy)
29
ATP
ATP
Electrontransportchain
proteins carbohydrates fats
aminoacids
glucose fattyacids
glycerol
acetyl CoA
Glycolysis
pyruvate
ATPCitricacidcycle
Photosynthesis vs. Cellular Respiration
30
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O2
O2
enzymesgranaPhotosynthesis
NADP+
CH2O
NADPH
CO2
enzyme-catalyzedreactions
NADH
enzymes
H2O
membrane
ATP productionvia chemiosmosis
ADP ATP
H2O
membrane
Cellular RespirationNAD+
cristae
CH2O CO2