In classic experiments that helped convince investigators that the chemiosmotic

Question

In classic experiments that helped convince investigators that the chemiosmotic hypothesis is true, artificial membrane vesicles were reconstituted with purified bacteriorhodopsin (which is a light-driven H+ pump from a photosynthetic bacterium) and purified ATP synthase from ox heart mitochondria. In these vesicles the membrane complexes are oriented so that protons are pumped into the vesicle and ATP synthesis occurs on the outer surface. When ADP and Pi were added to the medium surrounding the vesicles and the vesicles were illuminated with appropriate light, the interior of the vesicles became acidic and ATP was produced.

A. If, instead, the ATP synthase molecules were randomly oriented so that about half faced the outside of the vesicle and half faced the inside, would you expect ATP to be synthesized?

B. If the bacteriorhodopsin molecules were randomly oriented, would you expect ATP to be synthesized?

Explanation / Answer

A. If, instead, the ATP synthase molecules were randomly oriented so that about half faced the outside of the vesicle and half faced the inside, would you expect ATP to be synthesized?
yes
you can expect ATP at half the rate.
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If bacteriorhodopsin were randomly oriented, you would expect much
less ATP to be synthesized.

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