FINAL Answers WI04 scheffler

FINAL Answers WI04 scheffler - METABOLIC BIOCHEMISTRY Immo...

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METABOLIC BIOCHEMISTRY Winter 2004 Immo E. Scheffler FINAL EXAM All answers are to be written into the Blue Book. Leave the first inside page blank for scoring. There are 18 questions. Make sure that each answer is clearly identified with the question number at the top or left side of the page. Consider the statement on the back of the Blue Book; fill it out and sign it if you want to have your exam returned in the hallway outside of 3234 Bonner Hall. *********************************************************************************
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QUESTION 1 [12 points] a) NADH is oxidized via the mitochondrial electron transport chain with the eventual formation of water from oxygen. What are the complexes and mobile carriers involved in this oxidation, and what is the sequence of electron flow? (A simple schematic diagram with labels is required) [8]. the mobile carriers are ubiquinone (Q) and cytochrome c the matrix side and intermembrane space should be labeled b) Describe two major structures/constituents that can make a protein a conductor of electrons [4] 1) the insertion of a heme group to create a cytochrome that can conduct electrons 2) the formation of non-heme iron-sulfur centers (e.g. [2Fe-2S] and [4Fe-4S] )
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QUESTION 2 [10 points] The following diagram is a schematic representation of the oxygen concentration in a chamber containing mitochondria. Various substrates, inhibitors or uncouplers are added as indicated, with the result that oxygen consumption is either stimulated or arrested. For each of the substances added, rationalize the observed result. - malate glutamate are added to stimulate NADH production inside the mitochondria, but oxidation occurs in tightly coupled mitochondria, because the ∆Ψ will quickly build up and stop electron transport, because the pumps cannot overcome the electrochemical gradient. DY is kept high when protons cannot return to the matrix through the operation of the ATP synthase - when ADP is added we provide an acceptor for ATP synthesis by complex V, and protons can return to the matrix - rotenone is an inhibitor of complex I, hence respiration from NADH oxidation will stop - succinate can act as a substrate "downstream" from complex I, i.e. it is oxidized by complex II - malonate is a competitive inhibitor of complex II, and when added at sufficiently high concentration it can block the active site of complex II
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QUESTION 3 [8 points] a) Explain briefly how one can explain the experimental observation that the P/O ratio (ATP made per 1/2 O 2 consumed) is not an integer (i.e. 3.0 or 2.0) [5] Electron transport and respiration (oxygen consumption) and ATP synthesis take place in or on proteins that are physically not connected and coupled only by the electrochemical gradient across the inner membrane. This gradient can be dissipated by protons moving across to the inside by a number of ways: non-specific leakage, antiport and symport mechanisms, and uncoupling proteins. There is no fixed stoichiometry between NADH oxidation and ATP
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This note was uploaded on 09/11/2009 for the course BIBC BIBC 102 taught by Professor Price during the Spring '08 term at UCSD.

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FINAL Answers WI04 scheffler - METABOLIC BIOCHEMISTRY Immo...

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