4221172
Description
Mind Map by Sarah Emslie, updated more than 1 year ago
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Created by Sarah Emslie
over 8 years ago
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Electron Transport Chain and
Oxidative Phosphorylation
- Happens at inner mitochondrial membrane
- Chemiosmotic Theory
- Utilizing proton gradient to synthesize ATP
- Utilizing proton gradient to synthesize ATP
- Carbohydrates, lipids, and amino acids
are reduced fuels for the cell, electrons
from these are transferred to NAD+ or
FAD to make NADH and FADH2, these
can then be used in oxidative
phosphorylation to make ATP
- DG = -nFE
- High E indicates a strong tendency to be reduced
- Electrons are donated by the
half reaction with the more
negative E and accepted by the
reaction with the more positive
E
- Electrons are donated by the
half reaction with the more
negative E and accepted by the
reaction with the more positive
E
- High E indicates a strong tendency to be reduced
- Electron Transport Chain
- Four protein complexes in the inner mitochondrial membrane
- Lipid soluble coenzyme (CoQ) and water soluble protein (cyt c) shuttle between protein complexes
- Electrons fall in energy from Complexes I and II to Complex IV
- Complexes
- Each contains multiple redox centers
consisting of Flavin mononucleotide
(FMN) or Flavin Adenine Dinucleotide
(FAD)
- Initial electron acceptors for Complex I and II
- Can carry two electrons by transferring at a time
- Initial electron acceptors for Complex I and II
- Cytochromes a, b, or c
- Iron-sulfur cluster
- Complex I
- NADH-CoQ Oxidoreductase
- Electron transfer from NADH to Q
- Electron Path: NADH --> FMN --> FeS --> Q --> FeS --> Q
- Electron Path: NADH --> FMN --> FeS --> Q --> FeS --> Q
- 4 H+ transported out per 2 e-
- NADH-CoQ Oxidoreductase
- Coenzyme Q (Ubiquinone)
- Lipid soluble conjugated dicarbonyl
- Accepts two electrons, picks up
two protons to give an alcohol
ubiquinol
- Ubiquinol can freely diffuse in the
membrane, carrying electrons with
protons from one side to the other
- Lipid soluble conjugated dicarbonyl
- Iron Sulfur Clusters
- One electron carriers
- Coordinated by cysteines in protein
- Contain equal number of Fe and S atoms
- One electron carriers
- Complex II
- Aka: Succinate-CoQ
Oxidoreductase, succinate
dehydrogenase,
flavoprotein 2
- Three types of FeS clusters (4Fe-4S, 3Fe-4S, 2Fe-2S)
- Electron Path: succinate --> FAD --> Fe3+ --> Q
- Aka: Succinate-CoQ
Oxidoreductase, succinate
dehydrogenase,
flavoprotein 2
- Complex III
- CoQ-Cytochrome c Oxidoreductase
- CoQ passes electrons to
cyt c and pumps H+ in a
redox cycle known as the
Q cycle
- The main transmembrane protein in
Complex III is the by cytochrome
- Cytochromes are one-electron transfer units
- CoQ-Cytochrome c Oxidoreductase
- Complex IV
- Electrons crom cyt c are used in a four electron reduction of O2 to form H2O
- Oxygen is the terminal electron
acceptor in the electron transport
chain
- Electrons crom cyt c are used in a four electron reduction of O2 to form H2O
- Each contains multiple redox centers
consisting of Flavin mononucleotide
(FMN) or Flavin Adenine Dinucleotide
(FAD)
- Four protein complexes in the inner mitochondrial membrane
- Oxidative Phosphorylation
- Proton gradient is established
across the cristae membrane
in mitochondria
- ATP Synthase
- Made of two complexes, F1(matrix) and
F0 (inner membrane), both of which have subunits
- Alternating alpha and beta subunits in F1
- Conformation of beta subunit
changes between three different
conformations, open, loose (ADP + Pi)
and tight (ATP)
- Takes a lot of energy to release ATP from tight binding
- Takes a lot of energy to release ATP from tight binding
- Conformation of beta subunit
changes between three different
conformations, open, loose (ADP + Pi)
and tight (ATP)
- Gamma structure rotates
- Made of two complexes, F1(matrix) and
F0 (inner membrane), both of which have subunits
- Inhibition
- Rotenone inhibits Complex I,
cyanide, azide, and CO inhibit
complex IV, and oligomycin and
DCCD inhibit ATP synthase
- Rotenone inhibits Complex I,
cyanide, azide, and CO inhibit
complex IV, and oligomycin and
DCCD inhibit ATP synthase
- Uncouplers
- Disrupt tight coupling
between ETC and OP by
dissipating proton
gradient
- Hydrophoobic
molecules with a
dissociable proton
that shuttle across
the membrane
carrying protons
- Disrupt tight coupling
between ETC and OP by
dissipating proton
gradient
- ATP-ADP Translocase
- Moves ATP out of
the of the
mitochondria at
the cost of 1 H+
each
- Moves ATP out of
the of the
mitochondria at
the cost of 1 H+
each
- Regulation
- Lack of work means lack of demand for ATP
- Oxidative phosphorylation is
driven not by supply of fuel
but by demand for energy
- Lack of work means lack of demand for ATP
- P/O Ratio
- 2.5 for NADH electrons
- 1.5 for FADH2 electrons
- 2.5 for NADH electrons
- Proton gradient is established
across the cristae membrane
in mitochondria
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