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Diet to Die for CWK

Last updated about 5 years ago

3 questions

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Question 1

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CQ#4: You incubate isolated intact mitochondria in a buffered solution with succinate (an oxidizable substrate) and ADP plus Pi. You add oligomycin (the ATP synthase inhibitor), then the compound DNP (2,4-dinitrophenol), and examine the effect on oxygen consumption and the production of ATP. What do you predict? Hint: What happened when people took this as a weight-loss drug?

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Question 2

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CQ#5: You have created some artificial membrane vesicles (spherical lipid-bilayer enclosed droplets) that have a higher pH inside than the aqueous solution outside.  To sample 1 of these vesicles you add a little HCl, and to the other (sample 2) you add some DNP (with equivalent acidity) and then measure the internal pH of the vesicles. What do you predict will happen to the pH for each sample?

Question 3

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CQ#6. You isolate intact mitochondria and equilibrate them in a buffered solution at pH 9, containing 0.1 M KCl and ADP plus Pi, but without succinate. You collect them by centrifugation, and quickly resuspend them in a new buffer at pH 7, without KCl , but with valinomycin (a K+ ionophore). Note: the K+ rushing out will create a huge positive charge differential. What do you predict will be the result on oxygen consumption and the production of ATP?