Chemiosmosis
ADP -> ATP Concentration Gradient (Potential
Energy = [H+] Relation to Electron transport
chain Figure 6.7
Substrate-level Phosphorylation Phosphate group transferred to
ADP from substrate (FORM ATP!!!)
ATP production, but is small % in cell.
Systematic oxidation of organic compounds to release energy
May be anaerobic, i.e. in the absence of oxygen, or…
Aerobic, requiring oxygen.
Cellular Respiration
Oxidation is the loss of electrons Reduction is gain of electrons.. Oxidation and reduction always
happen together…
Remember electronegativity (ability to “grab” electrons: O > N > C > H)
Redox Review
Methane is a saturated hydrocarbon. When burned it is oxidized and energy is
given off. The overall equation is:
Oxidation of Methane
CH4 + 2O2 CO2 + 2H2O
Oxidation Statesof the central carbon atom...
O
C O
O
OHCH
CH H
O
H
Energy contained in the molecule….
REACTION
ENERGY
Glucose Oxidation
Glucose (Other organic molecules) broken down / rearranged to gain energy from within bonds.
C6H12O6 + 6O2 -------> 6 CO2 + 6 H2O+ ATP
(ENERGY)
Energy Use within the Cell
Cellular respiration “dismantles” glucose in a series of steps.
Energy from organic molecules (I.e. glucose) is harvested from the chemical bonds within the molecule.
Electrons are “shuttled” through a series of energy-releasing reactions.
Glucose loses H+ (Conversion to CO2) Oxygen gains H+ (Conversion to
Water)
H+ movements represent electron transfers.
Key Players in Redox Rxns Dehygrogenase = enzyme
NAD+ (nicotinamide adenine dinucleotide) = coenzyme
Both remove H atoms (& electrons) - - function as oxidizing agents.
The total oxidation of glucose will yield the same products as the total oxidation of methane...
Oxidation of Glucose
CH4 + 2O2 CO2 + 2H2O
C6H12O6 + 6O2 6CO2 + 6H2O
Mitochondrion
Graphic downloaded from - http://cellbio.utmb.edu/cellbio/mitoch1.htm
Outer membrane Matrix Cristae
Not visible: 1) Inner membrane, 2) Intermembrane space
ABOVE: Anaerobic respiration (in this case, alcoholic fermentation)
BELOW: Aerobic respiration.
Aerobic vs. Anaerobic
C6H12O6 + 6O2 6CO2 + 6H2OREDUCED OXIDIZED
38 ATPs
2C2H5OH + 2CO2C6H12O6 REDUCED OXIDIZED
2 ATPs
Cytoplasm
Mitochondrion
Locations of Cellular Respiration Processes
GLYCOLYSIS
OXIDATION ofPYRUVATE
KREBSCYCLE
ELECTRONTRANSPORT
ATP PhosphorylationNAD Reduction ATP is a nucleotide
NAD is a dinucleotide Both are formed in the process of
aerobic respiration Eventually all usable energy must be
stored in ATP
ATP - Phosphorylation
PPPPPP
ATPP + ADP
ENERGY
ENERGY
ATP - readily available chemical energy
Nicotinamide Adenine Dinucleotide - stores energy, but not readily available energy
ATP - NAD
PPP
PP
NAD gains energy when reduced
Electrons are always accompanied by hydrogens...
NAD - redox
NAD+
ENERGY
ENERGY
NADH + H +
e- + H+
e- + H+
Aerobic Respiration - Overview
GLYCOLYSIS
OXIDATION ofPYRUVATE
KREBSCYCLE
ELECTRONTRANSPORT
2 NADH
2 NADH
2 ATP
2 ATP
2 FADH6 NADH
10 NADH2 FADH
30 ATP4 ATP
GLYCOLYSIS (Exergonic) All living things follow the same steps
in the initial breakdown of glucose (C6) to pyruvic acid (pyruvate) (C3).
Some stop there, realizing 2 ATP in energy, others proceed further and realize as much as 38 ATP.
Respiration FlowChart
6O2
GlycolysisC6 ----> C3
C6H12O6
Electron Transfer System
Krebs (C.A.) CycleC2 ----> C
Oxid. of PyruvateC3 ----> C2
ATPCO2
NADH
H2O
FADH
OXIDATION of PYRUVATE In the process of glycolysis, one
molecule of glucose produces two molecules of pyruvate.
All living things perform glycolysis. Some anaerobically convert pyruvate
to ethyl alcohol, and others convert it to lactate.
The Aerobic Pathway
H3C
C = O
C = O
O-O
-
pyruvate
H3C
S - CoA
C = O
Acetyl CoA
CO2 S-CoA
NAD NADH
• Production of NADH
•Product is more oxidized than pyruvate
The Krebs Cycle(Citric Acid Cycle)
Entry of Acetyl CoA into Cycle
H2C
Citrate
HOC COO
COO
H2C
COO
H3C
S - CoA
C = O
Acetyl CoA
H2C
Oxaloacetate
C = O
COO
COO
S-CoA
Citrate to Isocitrate
H2C
Citrate
HOC
COO
H2C
COO
HOCH
Isocitrate
HC COO
COO
H2C
COO
H2O
COO
H2O
Isocitrate to Ketoglutarate
HOCH
Isocitrate
HC COO
COO
H2C
COO CO2 CO2
C = O
Ketoglutarate
H2C
COO
H2C
COO
NAD
NADH
Ketoglutarate to Succinate
CO2
C = O
Ketoglutarate
H2C
COO
H2C
COO
Succinate
H2C
COO
H2C
COO
NADNADH
ADPATP
Succinate to Fumarate
Succinate
H2C
COO
H2C
COO
Fumarate
HC
COO
HC
COO
FADFADH 2
Fumarate to Malate
H2O Fumarate
HC
COO
HC
COO
Malate
H2C
COO
HOCH
COO
Malate back to Oxaloacetate
Malate
H2C
COO
HOCH
COONAD
NADHH2C
Oxaloacetate
C = O
COO
COO
Respiration Flow Chart
6O2
GlycolysisC6 ----> C3
C6H12O6
Electron Transfer System
Krebs (C.A.) CycleC2 ----> C
Oxid. of PyruvateC3 ----> C2
ATPCO2
NADH
H2O
FADH
Electron Transport Chain
Reduction of NAD + to NADH + H+
NAD
NADH
H+
e NAD is a molecule that can be reduced by electrons that have been oxidized away from the carbon substrates…
NADH, in turn, can be oxidized and some other molecule reduced with its electrons...
OXIDIZED
REDUCED
H+
e
Reduction of the next electron acceptor, FMN NADH yields its electrons
and Hydrogen ions to FMN (Flavin Mononucleotide)
FMNH then can be oxidized and pass the electrons on to the next acceptor...
NAD
NADH
H+
e
H+
e
FMN
FMNH
H+
e
FMN
CoQ
Ct b
Ct c
Ct a
Ct a 3
NAD
Electron Transport Chain• as the electrons are passed on energy is lowered…• enough energy is transformed to make three ATPs for each reduced NADH…ATP
ATP
ATP
H2O
O
• the final electron acceptor is oxygen
FMN
CoQ
Ct b
Ct c
Ct a
Ct a 3
NAD
What about FADH2?
H2O
O
• FADH2 has less energy than NADH• it passes its electrons directly to Coenzyme Q, skipping one ATP step...
FAD
ATP
ATP
ATP
Glycolysis
ATP's Direct from C
Pathway
NADH's Produced
Pyruvic Acid Conversion to Acetyl CoA
Krebs Cycle
FADH2's Produced
22
Times Per
Glucose
Total ATP's Produced
ATP's per NADH or FADH2
1
31
1
x3
x3
x2x3
x1x1
x2
x2x2
x2
8
6
24
38Total ATP's per Glucose
ATP Arithmetic
•This chart is on page 9-2 of the A.P. Bio Study Guide
Chemiosmosis
The Mitochondrion Smooth outer membrane Folded inner membrane Inner folds are called cristae. Carrier molecules embedded in cristae.
OUTERMEMBRANE
INNER`MEMBRANE
CRISTA
INTER-MEMBRANOUS SPACE MATRIX
INTRAMEMBRANOUSSPACE
MATRIX
Active Transport Electrons (and hydrogens) build up in
matrix
e-
e-
e-H+
H+
H+
H+
INTRAMEMBRANOUSSPACE
MATRIX
Active Transport As electrons are transported, H’s are
pumped into IMS.
e-
e-
e-H+
H+
H+
H+
e-
H+H+ H+
INTRAMEMBRANOUSSPACE
MATRIX
Eventually a high chemiosmotic gradient of protons develops.
e-
e-
e-H+
H+
H+
H+
e-
H+H+ H+
H+
H+H+ H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
INTRAMEMBRANOUSSPACE
MATRIX
The only way for H+ to return is through ATP synthetase.
e-
e-
e-H+
H+
H+
H+
e-
H+H+ H+
H+
H+H+ H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
H+
ATP Synthetase
INTRAMEMBRANOUSSPACE
MATRIX
H+
H+
H+
H+H+H+
H+ H+
H+
H+
H+ H+
As H+’s move through ATP synthetase, ATP is formed in the matrix.
ATPADPH+