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125 Cards in this Set
- Front
- Back
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what is oxidized/reduced in the cac?
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citrate oxidized
nad+ and fad reduced |
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where does the cac take place?
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mitochondrial matrix
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where does the etc take place?
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inner mitochondrial membrane
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what is oxidized/reduced in the etc?
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molecular oxygen reduced
nadh and fadh2 oxidized |
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how do carbs enter cac?
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via glucose and glycolysis
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how do proteins enter the cac?
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aa's enter as pyruvate or acetyl coa
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how do lipids enter the cac?
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fatty acids to acetyl coa via beta oxidation
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what converts pyruvate to acetyl coa
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pyruvate dehydrogenase
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can pyruvate cross the inner mito membrane?
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yea
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what are the all the substrates in the pdh reaction?
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pyruvate, nad+ and coash
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what are all the products of the pdh rxn?
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acetyl coa, co2, and nadh h+
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describe pdh...
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huge multienzyme complex consisting of at least 3 types of enzymes
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list 5 coenzymes of pdh
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coenzyme A (coash)
nad+ thiamine pyrophosphate fad lipoic acid |
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the three types of enzymes in pdh?
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e1 (pyruvate decarboxlyase) multiple copies, contains bound tpp
e2 (dihydolipoyl transacetylase) multiple copies, uses coash as substrate and contains bound lipoicacid e3 (dihydolipoyl dehydrogenase multiple copies, contains bound fad and uses nad+ as substrate |
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mammalian pdh also contains multiple copies of:
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pyruvate decarboxylase (e1) kinase
pyruvate decarbosylase (e1) phophotase |
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what does pyruvate decarboxylase (e1) kinase do?
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catalyses the transfer of P from atp to e1 and make e1 less active
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what does pyruvate decarboxylase (e1) phosphotase do?
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removes P from e1 and make e1 more active
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what are the 3 parts of coenzyme A (coash)?
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3' P adp
pantothenic acid mercapto ethylamine |
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what is the business end of coenzyme A (coash)
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the sh group of mercapto ethylamine
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what is the business end of thiamine pyrophosphate, tpp?
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the C between N and S, forms a very reactive carbanion
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what's the business end of lipoic acid?
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the two sh groups
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lipoic acid condenses with...?
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and epsilon group on e2 lysine
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the diameter of the pdh is about?
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15 nm
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non allosteric effectors of pdh?
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acetyl coa and nadh
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non allosteric effect of acetyl coa on pdh?
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competitive inhibitor of E2, competes with coash
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non allosteric effect of nadh on pdh?
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competitive inhibitor of e3, competes with nad+
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allosteric effectors of pdh?
effect? |
acetyl coa and nadh
both inhibit |
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effect of phosphorylation on pdh?
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makes e1 less active
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effect of dephosphorylation on pdh?
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makes e1 more active
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effect of nadh on e1 phosphatase?
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inhibit
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effect of ca+2 on e1 phosphatase?
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stimulate+
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effect of insulin on e1 phosphatase?
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+stimulate
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effect of acetyl coa on e1 kinase?
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+stimulate
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what does e1 phosphotase do to the serine of e1?
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hydrolysis, remove P to make t more active
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what does e1 kinase do to the serine of e1?
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phosphorylates it to make it less active
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effect of nadh on e1 kinase?
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+
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effect of atp on e1 kinase?
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+
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effect of adp on e1 kinase?
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-
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effect of nad+ on e1 kinase?
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-
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effect of coash on e1 kinase?
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-
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effect of pyruvate on e1 kinase?
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-
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effect of ca+2 on e1 kinase?
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-
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which enzyme of cac is bound to the inner surface of the inner membrane of the mito?
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succinate dehydrogenase
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net in's of the cac?
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acetyl coa
3 nad+ 1 fad 1 gdp 1 pi |
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net out's of the cac?
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coash
2 co2 3 nadh 1 fadh2 1 gtp |
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some isoforms of succinyl coa sythetase catalyze the phosphorylation of
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adp instead of gdp
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oxidation of each nadh by o2 in the etc makes a max of how many atp?
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2.5
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oxidation of each fadh2 by o2 in the etc makes a max of how many atp?
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1.5
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what is the max net number of atp generated from oxidation of one molecule of glucose to give 6 co2's?
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32 atp's
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3 most exergonic and highly regulated enzymes of cac?
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citrate synthase, iso citrate dehydrogenase, and alpha ket0glutarate dehydrogenase
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citrate on citrate synthase?
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competitive product inhibition
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succinyl coa on citrate synthase?
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competitive feedback inhibition
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nadh on citrate synthase?
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allosteric feedback inhibition
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atp on citrate synthase?
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allosteric feedback inhibition
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adp on citrate synthase?
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allosteric activator
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nadh on isocitrate dehydrogenase?
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competitive product inhibition
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atp isocitrate dehydrogenase?
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allosteric inhibition
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adp isocitrate dehydrogenase?
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allosteric activation
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ca+2 isocitrate dehydrogenase?
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allosteric activation
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succinyl coa on alpha ketoglutarate dehydrogenase?
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competiive product inhibition
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nadh on alpha ketoglutarate?
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competitive product inhibition
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atp on alpha ketoglutarate dehydrogenase?
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allosteric inhibition
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ca+2 on alpha ketoglutarate dehydrogenase?
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allosteric activation
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what 3 variable affect flux through the citric acid cycle?
why? |
[Pi], po2, adp/atp
they affect the availability of nad+ and fadh2 |
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the inner mito membrane is how permeable?
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freely permeable only to h20, co2, 02
other molecule are tightly regulated |
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how permeable is the out mito membrane?
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freely permeable to most small molecules
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functions of the elctron transport chain?
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oxidize nadh and fadh2 to produce nad+ and fad needed for pathways suc as gylcolysis, the citric acid cycle and the beta oxidation of fatty acids
2. convert the energy released during the oxidation of nadh fadh2 into a form which can be used to drive the sythesis of atp form adp and pi |
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standard reduction potential
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the affinity of a molecule for electrons may be expressed as its standard reduction potential
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conditions of standard reduction potential
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25 degrees Celsius
1 atm 1M concentrations except h20 |
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biological standard reduction potential
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the pH in the test cell is 7
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best oxidizing agents have low/high affinity for e-?
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high
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best reducing agents have a low/high affinity for e-?
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low
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relationship between the change in G'o and change in E'o is given by the equation:
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change G'o = -nFchangeE'o
f is 96.48 KJ/volt mol n is the number of electrons exchanged |
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change in G'o from oxidation by o2 = ?
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-220 kj/mol
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change G'o released by atp?
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30.5 kj/moll
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theoretical oxidation of 1 nadh could synthesize how many atp's
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7.2
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actual oxidation of nadh yields how many atp?
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2.5
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factors that make E different that Eo'
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temperature (increase in temp decreases affinit for e-)
ratio ox form to red form (greater than one makes actual E more positive) |
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how energy from nadh oxidation used to make atp?
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chemiosmotic theory: energy used to make an H+ gradient across the inner membrane. free energy released when proton gradient is dissipated directly drives ATP synthesis
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observed ph of the matrix
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7.5
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observed ph of the intermembrane space
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6.75
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what is an uncoupler?
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chemical agent that dissipates the proton gradient without inhibiting electron transport
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key features of uncouplers?
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lipid soluble, can cross membrane
ionizable group |
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cytochromse?
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contain protein and heme group
may be classified on the basis of small variations in the type of heme constituents that is present donate/accept a single electron |
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iron sulfur clusters interact most often with what side chain?
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cys
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rieske FeS proteins coordinate with which side chains
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cys and his
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coenzyme Q
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ubiquinone
donate/accept 1/2 e- associated with an H+ hydrophobic, lipophyllic |
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complex 1 e- transfer
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from nadh to CoQ
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complex 1 H+ translocation
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4 H+
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complex 1 composition
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42 polypeptides
1FMN 6 or 7 Fe-S clusters each with a different (increasingly positive) Eo' |
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complex 1 components order
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nadh-fmn-FeS-CoQ
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complex II components
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4 polypeptides
1 fad 3 FeS clusters |
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complex II proton translocation?
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none
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complex II transfers e- from succinate to?
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CoQ
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complex III accepts electrons from ?
transfers electrons to? |
CoQH2
Cyt c |
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complex III is dimeric, each polymer consisting of?
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11 polypeptides
2cytochromes 1 rieske FeS protein |
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Complex IV accepts electrons from?
transfers electrons to? |
Cyt c
O2 |
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Complex IV is dimeric, consisting of
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13 polypeptides
2 cytochromes 3 copper atoms |
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complex III translocates how many H+?
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4
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complex IV translocates how many H+?
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2
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what are 2 mechanisms by which protons may be moved across the mito inner membrane
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redox loop model
proton pump model |
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what is the redox loop model
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protons are ferried across teh membrane by a membrane souble proton carrier that is reduced on one side aof the membrane and oxidized on the other (probably III with coq as H+ carrier, possibly I with fmn as the H+ carrier)
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what is the proton pump model?
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reduction of a transmembrane protein causes a conformational change that transllocates one or more protons form one side of the membrane to the other (probably the mechanism by which complex IV traslocates H+'s)
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change G out to in =
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RT*ln ([in]/[out])
or change U out to in*FZ (z=charge on substance being translocated. |
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change U out to in =
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-0.15 volts
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the synthesis of 1 atp in the matrix requires a total influx of how many protons?
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4
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how many KJ/mol does it to make 1 atp?
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45
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one H+ influx results in how many kj/mol?
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19
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what is the FO pore of atp synthase made of ?
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10 to 12 c protiens, 1 a protein, and 2 b proteins
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what does f1 of atp synthase do?
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catalyses atp synthesis
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f1 is made of
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3 alpha beta protomers
y, gamma protein (alpha and beta around it) |
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what holds alpha and beta's stationary relative to gamma?
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delta protein with the 2 b and 1 a protein
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what is the epsilon protein's role?
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links the gamma protein to the pore
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how does the atp synthase work?
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see page 24
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how many protons are required to drive the atp sythase?
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3
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how many protons does it take to import pi and adp and export 1 atp/
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1
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1 nadh may export how many protons?
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10
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1 fadh2 exports how many protons?
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6
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how do nadh produced in the cytosol enter the etc?
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malate aspartate shuttle and glycerol P shuttle
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how many atp are produces per cytosolic nadh?
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2.25
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how many protons are exported by the oxidation of 1 cytosolic nadh?
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9
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how does the malate-aspartate shuttle work?
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see page 29
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how does the glycerol P shuttle work?
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see page 29
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advantages of malate/aspartate shuttle? disadvantages?
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2.25 atp/ cytosolic atp
inhibited by high matrix nadh |
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advantages of glycerol shuttle? disadvantages?
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independent of matrix nadh
1.5 atp/cytosolic nadh |
