706_F06pset4 - 7.06 Fall 2006 Problem Set #4 1. How is...

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7.06 Spring 2006 PS4 – revised 1 of 3 7.06 Fall 2006 Problem Set #4 1. How is glucose transported from the lumen of the intestine across the intestinal epithelium into the blood? Explain the proteins and concentration gradients involved. 2. Cholera toxin, produced by Vibrio cholerae , a pathogenic intestinal bacterium, causes an indirect reduction in the activity of the Na + /K + ATPase in intestinal epithelial cells. This results in reduced uptake of small sugars and amino acids from the intestine. Why does this reduction in uptake result from impaired Na + /K + function? 3. When present in the culture medium, a drug called ouabain inhibits the Na + /K + ATPase in cultured cells, but when the drug is microinjected into cells, it exerts no inhibitory effect. Although ouabain itself possesses no negative charge, ouabain treatment causes the alpha subunits of the Na + /K + ATPase to become more negatively charged but does not alter the charge properties of the beta subunits. a. On which side of the plasma membrane is the ouabain- and ATP-binding sites of the ATPase located?
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This note was uploaded on 01/23/2012 for the course BIOLOGY lsm1301 taught by Professor Seow during the Spring '11 term at National University of Singapore.

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706_F06pset4 - 7.06 Fall 2006 Problem Set #4 1. How is...

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