L32 Mitochondrial Electron Transport Chain Flashcards
What is the METC
final common pathway in aerobic cells by which electrons derived from various compounds are transferred to O2 to form H20
How does energy production occur in ETC
1-electron transport between diff complexes (oxidation)
2-proton pumping in to inter membrane space
3-synthesis of ATP from ADP and Pi(phosphorylation)
Describe Complex I
Ubiquinone oxidoreductase Formed of: .many polypeptides .FMN co enzyme .7 FeS centers .Es are transferred from NADH to FMN to diff FeS Centers then UQ to be reduced to UQH2
4 protons pumped
Describe complex II
Succinate: ubiquinone oxidoreductase Formed of: Succinate dehydrogenase FAD coenzyme Two FeS centers Catalyzes transfer of e’s from FADH2(released by oxidation of succinate) to UQ To form UQH2
No protons pumped
Describe complex III
Ubiquinone:(ferri cytochrome C oxidoreductase)
Formed of
ONE FeS center
Cytochrome b
Cytochrome c1
Transfers electrons from UQH2 to cytochrome C
3 protons pumped
Describe Complex IV
Ferro cytochromeC: oxygen oxidoreductase
Two cytochromes (a and a3) Two atoms of Cu
Transfers two e’s from cytochrome C to oxygen which combines with 2 H+ to form h2O
4 protons pumped
What do cytochromes contain
Heme group made of a porphyrin ring containing and atom of iron
Iron atom is reversibly converted from Fe 2+to Fe3+
Describe cytochrome and its function
Mobile element of ETC
in inter membrane space loosely associated with outer face of inner membrane
Electrons passed along the chain from cytochrome bc1(complex III) to cytochrome c and then cytochrome a+a3(complex IV)
How are electrons insured to flow from beginning to end of ETC
Components of ETC are arranged according to their oxidation reduction potential
What are the coupling sites at which proton pumping occurs
Coupling site I: in between FMN(in complex I) and CO Q
Coupling site II: between cytochrome b and c1 (in complex III)
Coupling site III: at cytochrome a and a3 (in complex IV)
Describe ubiquinone and its function
Made from an intermediate of cholesterol synthesis
Links flavoprotein dehydrogenases to cytochromes
Whats a drawback of the ETC
Potential leakage of electrons outside of mitochondria and formation of reactive oxygen species which have deleterious effects on all body molecules and can cause cancer
How many protons does one ATP molecule need to be formed
4 protons
How is respiratory chain controlled
By inhibitors
A) inhibitors of respiratory chain proper
B) inhibitors of oxidative phosphorylation
C) uncouplers of oxidative phosphorylation
Explain how inhibitors of respiratory chain proper work
Inhibit ETC and thus proton pumping examples: Barbiturates:sleeping medicine Piercidin A: antibiotic Rotenone: rat poison Antimycin :anti fungal Hydrogen sulfide gas carbon monoxide Cyanide (poison)