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SGU: Oxidative Phosp

Biochem: Oxidative Phosphorylation

QuestionAnswer
How are electrons transported to NAD, FAD, FMN, Q, cytochrome? hydride ions to NAD and hydrogen atoms to FAD, FMN, Q, transported as electrons to cytochromes
What is the standard reduction potential? tendency to gain electrons for a given redox pair
Negative reduction potential? tendency of the reduced partner to lose electrons increases
Positive reduction potential? tendency of the oxidized partner to lose electrons increases
With respect to reduction potential, electrons will move? from the partner with a negative reduction potential to the partner with a positive reduction potential
What is the P/O ratio? ATP formed:Oxygen atom reduced
P/O ratio for NADH? 3 ATP:1 NADH
P/O ratio for FADH2? 2 ATP:1 FADH2
Why are 2.5 ATP synthesized for each NADH instead of three? because it takes 4 protons to make an ATP and NADH oxidation only transports 10 protons
What is Mitchell's hypothesis/chemiosmotic theory? proton pumps establish a chemiosmotic gradient in which complex 1, 3 and 4 pump protons into the intermembrane space giving it a high pH and positive charge as compared to matrix. Energy generated by proton gradient drives ATP synthesis
What couples oxidation to phosphorylation? the proton gradient
The electron transport chain is stopped if the energy to move protons out of the matrix is smaller than the energy lost to heat, if energy of gradient is not dissipated
What is the Fo domain of the F1/F0 ATPase? spans the inner membrane, the proton channel
What is the F1 domain of the F1/F0 ATPase? extended out into the matrix, the catalytic subunit
How is F1 held into place? S and b2 subunits
Describe rotational catalysis when a proton is transferred the rotator stalk (gamma-epselon subunit) has a conformational change and rotates on the immobile F1 subunit, catalyzing ATP
What is the function of oligomycin? inhibits ATP synthase by binding to the F0 domain thus closing the proton channel, electron transport is halted
What is a symptom of oligomycin? lactic acidosis in the blood
What molecules uncouple electron transport from phosphorylation? uncoupling proteins:cause proton's to leak across inner mito membrane: UPC1, ionophores, 2,4-Dinitrophenol, CCCP, FCCP
What happens to energy released from electron transport that is not coupled to phosphorylation? Released as heat called nonshivering thermogenesis
Where does nonshivering thermogenesis occur and how? UCP1/thermogenin causes heat production in brown fat by making a pore in the inner mito membrane and dissipating the proton gradient
What is irreversible uncoupling or ETC block? ETC block
What is the effect of 2,4-Dinitrophenol (DNP)? used as dyes, preservatives, pesticides, dangerous diet agent, binds protons on one side and moves in to the other because it is fat soluble
Effects of CCCP and FCCP? lipid soluble weak acids which are powerful uncouplers
What uncouplers are found naturally in the body? UPC1 in brown fat, UPC2 & UPC3 found in other cells.
What is UPC2 & UPC3 used for clinically? target for weight loss but can increase risk of diabetes in pancreas beta cells
Examples of ionophores gramicidin, valinomycin, nigericin
Function of gramicidin channel forming by dimerization to form beta-helix
Function of valinomycin associtaed with carying K across bilayers, keeps ion distribution in accordance with the Nernst equation when at equilibrium
Function of Nigericin mobile carrier, H+/K+ antiporter, can move across lipid membranes b/c it's carboxyl group and a K+ makes the charged ion neutral
Function of Adenine nucleotide translocase? antitransporter of ATP and ADP, symport of Pi and H+
What is the function of Atractyloside? glycoside that binds outward faceing intermembrane space portion o fthe adenine nucleotide transporter, inhibits transporter
Function of Bongkrekic acid? binds the inward facing matrix portion of the adenine nucleotide transporter, inhibits transporter
What is the effect of inhibition of ADP/ATP transport? inhibit ATP production/stall ETC
What is the function of NSAIDS on oxidative phophorylation? can uncouple ox phos, decrease ATP synthesis, inhibit adnenine nucleotide translocase
How is cytochrome C is released from the mito during apoptosis? pore formation in the outer mito membrane
What genes are encoded by the mito genome? complex 1, 3, 4, 5
What is a major signal/symptom of ETC and ox phos disorders? lactic acidosis
What kind of inheritance is seen in ETC and oxidative phosphorylation disorders? maternal inheritance, autosomal dominant, recessive or sex-linked, mutations in one or more of the 13 proteins coded on the mito genome
What diseases are caused by mutation in mito DNA of complex 1? Leber's hereditary optic neuropathy (LHON), LHON Dystonia, mito encephalomyopathy-lactic acidosis-stroke like episodes (MELAS)
Diseases caused by mutation of mito DNA of complex 5? Leigh's Disease, myoclonic epilepsy with ragged-red fibers (MERFF), neuropathy-ataxia-and retinitis pigmentosa (NARP)
How many of the genes for oxidative phosphorylation are coded by mito DNA? 13 of 120
What affects mutation rate of mito DNA? more ATP atissue needs, the more it is affected by mito defects because mutation rate is 10x greater than nuclear DNA
What is the usual inheritance of mtDNA diseases? maternal
What is mitochondrial myopathy? abnormal proliferation of mito
What is Leber hereditary optic neuropathy? bilateral loss of central vision occurs due to neuroretinal degen
What is Leigh syndrome? Affects the brainstem and basal ganglia and is charcterised by defects in mito oxidative phosphorylation
What is rhabdomyolysis? breakdown of muscle due to injury, toxins or metabolic disease which leads to high [] of myoglobin in both plasma and urine
What is ragged red fibers? pathological hallmark of mtDNA disease characterized by subsarcolemmal accumulation of abnormal mito in the muscle fiber, which stain red with a Gomori trichrome stain
Created by: mnoronha on 2011-02-19



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