1) Artificial, but functional, electron transfer systems can be made in the lab by building artificial membrane-bound vesicles. This is done by combining detergent-solubilized, purified respiratory complexes and membrane lipids. When the mixture is dialyzed to remove the detergent, liposomes spontaneously form that contain the protein complexes integrated into the "membrane." The central cavity of the liposome can be made to contain certain molecules in aqueous solution; the surrounding medium can also be manipulated. Using this protocol, you create the following electron transfer systems in liposomes, containing the listed set of components (not necessarily in their functioning order) along with the specified initial electron donors. Place the components in their correct functional sequence and indicate the final electron acceptor in each case.

(a) NADH as initial electron donor; Q and Complexes I, III, and IV in the liposomes; oxygen is present.

(b) NADH as initial electron donor; Complexes I, II, and IV in the liposomes; oxygen is present.

(c) Succinate as initial electron donor; Q, cytochrome c, and Complexes II, III, and IV in the liposomes; oxygen is present.

2. (a) If the orientation of the mitochondrial ATP synthase were reversed so that the F1 unit were on the opposite side of the inner mitochondrial membrane, and assuming that nothing else is changed in the cell, what would be the consequences to the cell? Explain.

(b) What would be the consequences if just the Fo complex were flipped within its membranous surroundings, so that its normally matrixfacing surface faced the intermembrane space? Assume the F1 complex is still on the matrix side.

pur-new-sol

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