BCHM-3050 Lecture Notes - Lecture 14: Succinic Acid, Q Cycle, Oxidoreductase
26 Jun 2018
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Chapter 14: Electron Transport
Overview
Relatively little ATP is generated in stage 1 and stage 2.
Stages 1 & 2 = product a total of 10 moles of NADH and 2 moles of FADH2 per mole of glucose.
Reoxidatiob of NADH to NAD+ and FADH to FAD in stage 3 is known as cellular respiration provides
most of the energy used for ATP synthesis.
Mitochondria Compartments
Site of the ETC
oInner Membrane
Electron Transport
Oxidative Phosphorylation
Oxidative Phosphorylation
Takes place on the inner mitochondrial membrane
Complex I, III, and IV pump protons into the intermembrane space creating an energy/proton gradient.
Complex V (ATP synthase) uses the energy stored in this gradient to drive ATP synthesis.
Reduction Potential and Free Energy
The standard free energy change for a redox reaction is directly related to the difference in reduction
potentials.
The redox reaction is FAVORABLE (negative delta G) when the change in the standard reduction
potentials is positive (E acceptor > E donor)
Electron Carriers
Respiratory chain stimulates the flow of electrons from low/negative reduction potential carrier to
high/positive reduction potential carriers and is EXERGONIC
Uses a variety of electron carriers:
oComplex I: contains FMN
oComplex II: contains FAD and are called flavoproteins
Both are bound to the protein
oComplexes I, II, and III contain non-heme iron-sulfur clusters such as FeS and Fe4S4 and are
called iron-sulfure proteins.
Conenzyme Q shuttles 2 electrons from complex I to III and II to III.
Complexes II and III are cytochromes and contain hemes
Structures of Iron-Sulfur Clusters
Reduction potentials of iron-sulfur clusters can vary greatly depending on the type of cluster and the
protein environment
Cluster “types” include:
o2Fe-2S
o3Fe-4S
o4Fe-4S
(can also include non-Fe metals and are involved in single electron carriers)
Coenzyme Q
Lipophilic electron carrier:
oExists WITHIN the hydrophobic core of the mitochondrial inner membrane.
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Relatively little atp is generated in stage 1 and stage 2. Stages 1 & 2 = product a total of 10 moles of nadh and 2 moles of fadh2 per mole of glucose. Reoxidatiob of nadh to nad+ and fadh to fad in stage 3 is known as cellular respiration provides most of the energy used for atp synthesis. Site of the etc: inner membrane. Takes place on the inner mitochondrial membrane. Complex i, iii, and iv pump protons into the intermembrane space creating an energy/proton gradient. Complex v (atp synthase) uses the energy stored in this gradient to drive atp synthesis. The standard free energy change for a redox reaction is directly related to the difference in reduction potentials. The redox reaction is favorable (negative delta g) when the change in the standard reduction potentials is positive (e acceptor > e donor)
