ETC & OP
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Transcript of ETC & OP
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1
In The name of Almighty Allah, The Merciful, The
Beneficent
Assalam u Alykum WRWB
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Electron transport and Oxidative
Phosphorylation
Objectives
1. Define reducing equivalents and outline their sources and fates.
2. List the components of electron transport chain and describe the processof electron transport
3. Define energy, energy currency (ATP) and energy storage (creatinephosphate) ad describe the functions of Creatine phosphate and ATP.
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Energy and Free energy
All biochemical processes (reactions)involve the energy transactions
Exergonic reactions release energy
Endergonic reactions- consume energy
The actual energy available to do work(utilizable) is known as free energy.
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The free energy stored in
food stuffs is extracted in the
form of reducing equivalents.
The reducing equivalents aretransferred to ETC via different
carriers like NAD, FAD, FMN
etc
ATP is synthesized by oxidativePhosphorylation.
Reducing equivalents
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The reducing equivalents are defined as a proton plus anelectron, H+ + e-
Are transported Via Conjugate oxidant/reductant pairs
NAD-NADH
FAD-FADH2
FMN-FMNH2 Redox Potential (E
0): is the quantitative measure of tendency
of a redox pair to loose or gain electrons.
A more negative E0means a greater tendency to looseelectrons, and a positive E
0means a greater tendency to gainelectrons.
Reducing equivalents
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Electron Transport chain
(ETC) E
TC present in inner mitochondrialmembrane as four complexes
Complexes I, III and IV do the pumpingof protons
These are transmembrane proteincomplexes containing quinones, flavinnucleotides, sulfur clusters, hemes,and copper ions.
The inner membrane (IMM) isimpermeable to ions and polar
molecules. Specific transporters shuttlemetabolites such as ATP and organicions.
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4H+
INTERMEMBRANE SPACE
OH-
ATP4-
F1
Fo
3H+
MATRIXstalk
3H+
Proton gradient/Charge gradient
FMNH2
H+
complex I
CoQ
cyt bcomplex III
C1
Ccyta-a3
H+H+
O2
e-
H2O
NADH
+ H+
inner
membraneNAD
+
Pi-
e-
e-
e-
e-e-
e-
e-e-e-
H+
H+
complex IV
ADP3-
ATP4-
ATP
4-
ATP4-
OH-
OH-
ADP3-
ADP3-
ADP3-
ADP3-
ADP3-
ADP3-
ADP3-
Electron transport and Oxidative Phosphorylation
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Oxidative Phosphorylation
Definition:
Oxidative Phosphorylation isthe process in which ATP isformed as a result of the
transfer of electrons fromNADH and FADH2 to O2 by ETC.
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Mechanism of Oxidative Phosphorylation
( Chemiosmotic hypothesis and binding change model)
The Electron transport throughETC is coupled with translocation of
protons across IMM.
This results in the formation of an electrochemical gradient i.e. more H+ on
outer side of IMM than inside. The Protons flow back into the mitochondrial matrix and induce a
conformational change in the enzyme ATPase which synthesizes ATP from
ADP and Pi.
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High Energy Compounds
Definition: Certain compounds which on hydrolysisyield at least 7cal/mol free energy at pH 7.0 areknown as high energy compounds.
Classification Pyrophosphates e.g. ATP
Acyl Phosphates e.g.1,3-bisphosphoglycerate
Enol Phosphates e.g. Phosphoenolpyruvate
Thioesters e.g. Acetyl Co A
Phosphagens e.g. Creatine Phosphate
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ATP- The Energy Currency of Cell
ATP made up of adenine, ribose and a triphosphate moiety.
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ATP is a unique and most important high energy molecule in
the body due to presence of two high energy phospho-anhydride bonds.
ATP is hydrolyzed to yield energy
ATP + H2O ADP +Pi + 7.3 Cal
ATP serves as the Energy currency of Cell as it is beingconstantly utilized and regenerated in ATP-ADP cycle.
ATP also acts a phosphate donor to low energy phosphate
compounds.
ATP serves as a link between Catabolism and Anabolism inbiological system.
ATP- The Energy Currency of Cell-contd
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Creatine Phosphate (CP) is the reservoir ofenergy in muscles. CP donates its phosphate toADP to form ATP by Enzyme CreatinePhosphokinase.
When muscles contract (active muscle) energy isderived from breakdown of ATP to ADP and Pi.
ATP must be reformed quickly to supply theenergy which initially comes from creatinephosphate and subsequently from glycolysis.
In resting muscle Creatine is againphosphorylated and energy is stored as CP.
Storage forms of high Energy Phosphate
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G0
Compound (kJ/mol) ( kcal/mol)
Phosphoenolpyruvate 61.9 14.8Carbamoyl phosphate 51.4 12.3
1,3-Bisphosphoglycerate 49.3 11.8
(to 3-phosphoglycerate)
Creatine phosphate 43.1 10.3
ATP ADP + Pi 30.5 7.3ADP AMP + Pi 27.6 6.6
Pyrophosphate 27.6 6.6
Glucose 1-phosphate 20.9 5.0
Fructose 6-phosphate 15.9 3.8
AMP 14.2 3.4
Glucose 6-phosphate 13.8 3.3
Glycerol 3-phosphate 9.2 2.2
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Thank you very much
with All the best
wishes