Ch 18.5

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Ch 18.5
2014-12-02 05:08:54
Test four
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  1. ·         __ facilitate exchange across the inner membrane
    ·         One function of the chain is to __
    o   NADH cannot simply __because the inner mitochondrial membrane is impermeable to NADH an NAD+. The solution is that __
    • Transport proteins
    • regenerate NAD+ for use in glycolysis
    • pass into mitochondria for oxidation by the respiratory chain 
    • electrons from NADH, rather than NADH itself, are carried across the mitochondrial membrane
  2. §  One of several means of introducing electrons from NADH into the ETC is the __
    ·         The first step in this shuttle is the __ on the outer surface of the inner mitochondrial membrane by a __
    o   An __is transferred to an __ in this enzyme to form __
    §  This reaction also regenerates __
    • G3P shuttle
    • transfer of a pair of electrons from NADH to dihydroxyacetone phospahate
    • membrane-bound isozyme of G3P dehydrogenase
    • electron pair from G3P 
    • FAD prosthetic group
    • FADH2
    • dihydroxyacetone phosphate
  3. ·         The reduced flavin transfers its electrons to the __, which then enters the respiratory chain as __.
    o   When cytoplasmic NADH transported by the __ is oxidized by the respitaroy chain, __ rather than __ are forme
    §  The yield is lower because __
    • electron carrier Q
    • QH2
    • G3P shuttle
    • 1.5 rather than 2.5 molecules of ATP
    • FAD rather than NAD+ is the electron acceptor in mitochondrial glycerol 3-phosphate dehydrogenase
  4. o   The use of FAD enables electrons from cytoplasmic NADH to be __
    §  The price of this transport is __
    ·         This G3P shuttle is prominent in muscle and enables it to sustain a very high rate of __
    • transported into mitochondria against an NADH concentration gradient
    • one molecule of ATP per two electrons
    • oxidative phosphorylation
  5. ·         In the heart and liver, electrons form cytoplasmic NADH are brought into mitochondria by the __, which is mediated by __ and __
    o   Electrons are transferred from NADH in the cytoplasm to __, forming __, which traverse the inner mitochondrial membrane in exchange for __ and is then reoxidized by __ in the matrix to form __in a reaction catalyzed by the __
    • malate-aspartate shuttle
    • two membrane carriers and four enzymes
    • oxaloacetate
    • malate
    • alpha-ketoglutarate
    • NAD+
    • NADH 
    • CAC enzyme malate dehydrogenase
  6. §  The resulting oxaloacetate does not do what and so a __reaction is needed to form __, which can be transported to the cytoplasmic side in exchange for __, which donates an __ to __, forming __ and __. 
    • readily cross the inner mitochonodrial membrane
    • transamination 
    • aspartate
    • glutamate
    • amino group
    • oxaloacetate
    • aspartate and alpha-ketoglutarate
  7. ·         In the cytoplasm, aspartate is __to form __and the cycle is restarted
    ·         The major function of oxidative phosphorylation is to generate ATP from ADP
    o   ATP and ADP do not diffuse freely across the __
    §  __ enabels the molecules to transverse this permeability barrier
    • deaminated 
    • oxaloacetate 
    • inner mitochondrial membrane
    • ATP-ADP translocase
  8. ·         The flows of ATP and ADP are coupled
    o   explain
    §  The process is carried out by the __, an __
    • ADP enters the matrix only if ATP exits, and vice versa
    • translocase
    • antiporter
  9. ·         __ is highly abundant, constituting about 15% of the protein in the inner mitochondrial membrane
    o   The abundance is a manifestation of the fact that human beings exchange the equivalent of their weight in ATP each day
    §  The 30-kd translocase contains a __ that alternately faces the matrix and the cytopaslmic side of the membrane
    • ATP-ADP translocase
    • single nucleotide-binding site
  10. ·         ATP and ADP bind to the __without __, and ATp has one more __ than that of ADP
    o   Thus, in an actively respiring mitochondrion with a positive membrane potential, __ and __ are favored
    §  This __ is energetically expensive; about a quarter of the energy yield from electron transfer by the respiratory chain is consumed to do what?
    ·         This inhibition of this process leads to the subsequent inhibition of cell resp
    • translocase 
    • Mg2+
    • negative charge
    • ATP transport out of the mitochondrial matrix and ADP transport into the matrix
    • ATP-ADP exchange
    • regenerate the membrane potential that is tapped by this exchange process
  11. ·         ATP-ADP translocase has __ of a 100-amino-acid module, each of which appears to have __
    o   The transmembrane helices form a tepeelike structure with the __ (marked by a bound inhibitor) lying in the center
    §  Each of the three repeats adopts a similar structure
    • three repeats
    • two transmembrane segments
    • nucleotide-binding site
  12. ·         __ is but one of many mitochondrial transporters for ions and charged metabolites

    o   The __ mediates the electroneutral exchange of __ for __
    §  The combined action of these two transporters leads to the __(owing to the transport of one OH- out of the matrix)
    ·         These two transporters, which provide ATP synthase with its substrates, are associated with the synthase to form a large complex called the __
    • ATP-ADP translocase
    • phosphate carrier
    • H2PO4- for OH-
    • exchange of cytoplasmic ADP and Pi for matrix ATP at the cost of the influx of one H+ 
    • ATP synthasome
  13. ·         Other homologous carriers also are present in the inner mitochondrial membrane
    o   The __ enables malate, succinate, and fumarate to be exported from the matrix in exchange for Pi
    §  The __ exchanges citrate and H+ for malate
    ·         Pyruvate in the cytoplasm enters the mitochondrial membrane in echange for OH- by means of the __
    • dicarboxylate carrier
    • tricarboxylate carrier
    • pyruvate carrier

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