ATP _ Universal Carrier of Free Energy

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ATP _ Universal Carrier of Free Energy
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Role of ATP in Metabolism

• Memorize this structure!!!!
• Its the most important molecule in biochemistry.

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The Concept
Energy rich molecules donate electrons to
specific coenzymes to form energy-rich
reduced coenzymes
These electrons are donated to the
electron transport chain to form ATP
1 pair of electrons is donated per each reduced
coenzyme
H2 H H
H 1 electron 1 proton
H 2 electrons 1 proton
(Hydride ion) H 1 proton
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Electrochemical gradient
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Glycolysis
Cytoplasm
(Cristae)
Electron Transport
Contains the ATP Synthetase complex

• Inner mitochondrial membrane

• Is the final common pathway
• by which electrons from food
• molecules are used to make
• ATP and molecular oxygen
• acts as the final acceptor
• of the electrons

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Final acceptor of e-s is molecular oxygen
NADH Dehydrogenase
Cytochrome oxidase (Iron copper)
Complex V contains ATP Sythase

• Series of Oxidation/Reduction reactions

Electron transport chain ? 3 components

• Flavoprotein ? NADH Dehydrogenase

• CoQ (Quinone) ? Ubiquinone

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Cyanide
Each one of these inhibitors will completely stop
electron transport and thus all ATP production
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Three Main Tenets of the Mitchell Theory
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ATP Synthase
This dissipates gradient
Oligomycin blocks
Lower pH
More protons
pH gradient
Electrical gradient
ATP
Cytoplasm
1 NADH 3 ATP
1 FADH2 2 ATP
Chemiosmotic Hypothesis of Electron Transport
coupled to ADP Phosphorylation ? Mitchell
Hypothesis
Features

• Protons transported from the matrix to the inner
  mitochondrial space results
• in an electric gradient and a pH gradient

• As the protons flow through the membrane channel
  back into the matrix
• they drive ATP synthesis

Occurs with energy utilized by ATP synthase
This proton transport couples electron transport
to oxidative phosphorylation
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Uncoupling of Oxidative Phosphorylation
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Brown adipose tissue creates heat by thermogenesis
Thermogenin uncoupling protein ? UCP1
Mechanism is to ? FA oxidation which uncouples
oxidation phosphorylation
The energy is given off as heat
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Inherited Diseases of Oxidative Phosphorylation
LIBERS HEREDITARY OPTIC NEUROPATHY
Bilateral loss of central vision occurs because
of Neuroretinal degeneration
Mutation in mitochondrial DNA
Mitochondrial DNA is maternally inherited because
all mitochondria come from the mother
None come from the sperm because none from sperm
enter the egg during fertilization
13 of the 100 proteins in the mitochondrion
are coded for by mtDNA
Has mutation rate gt 10x that of nuclear DNA
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2 Shuttle systems to bring cytosolic NADH
into mitochondria for oxidative phosphorylation
1) Glycerophosphate shuttle 36 ATP
2) Malate-aspartate shuttle 38 ATP
Count ATPs Anerobic glycolysis 2
Glycolysis CAC oxidative
phosphorylation 38
NADH FADH2 ATP
1 Glycolysis 2
2 Glycolysis (G-3-P ? 1,3,BisP) 2 6
3 Pyruvate ? Acetyl CoA 2 6
4, 5, 6 CAC 6 18
7 CAC-FADH2 2 4
8 CAC substrate level ATP 2
Total 38
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Revolves at 100 Hz (revolutions/s)
This is sufficient to produce a turnover of The
weight of our body of ATP each day!
ATP synthase

• Rotates in 120 stages

• 100 Hz one complete revolution 3 ATP

• Need 10 H

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Bioenergetics _ Describes the transfer and
utilization of energy in biologic systems
Predicts if a reaction is possible
Sign of DG predicts direction of the reaction
Negative DG
v Reaction goes spontaneously
v Is a net loss of energy
The Rx is Exergonic
Positive DG
v Reaction not spontaneous
v Energy must be added
The Rx is Endergonic
Zero DG
and disorder.
Reactants are in equilibrium