2730312-dt-content-rid-20530634 1/courses/B2740-1552/F09Exam2pdf assonline.net L

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2730312-dt-content-rid-20530634 1/courses/B2740-1552/F09Exam2pdf assonline.net Lab section page 6 of 7 6. You are testing the rate of glucose transport into vesicles using a Na-glucose pump. This transporter protein transports Na" and ghucose in the same direction, and is a coupled transporter such that binding of either Na" or glucose increases the affinity of the transporter to bind the other solute. In experiment 1, you create artificial vesicles that have the Na-glucose pump in the membrane. These vesicles have glucose but no Na" ions inside. rah forprin You place these vesicles into a series of tubes containing the same glucose concentration as the inside of the vesicle. These tubes vary in their Na" concentration, with 0, 1, 2, 3, or 10 mM Na. Your results from your measurements of the initial rates of glucose transport into the vesicles with the varying concentrations of Na' are on the graph (see experiment 1) ) Explain why glucose is not being transported when there is no Na* in the external solution. 3 points) n) Explain why the initial rate of glucose transport into the vesicle plateaus as the concentration of Na increases. (5 points) bp

Explanation / Answer

i). Since the Na+-glucose pump is the symporter so it will transport glucose from outside to inside of cell only when Na+ ion is present in extracellular space if there is no Na+ ion in extracellular space then no more Na+ ion available to bind to the pump. In result of that Na-glucose pump will be nonfunctional.

ii). Initially when the conc. of the sodium is low, at that time rate of glucose transport will increase with the increase of Na ion conc. and behaves as the first order reaction.  

After sometime when the all the pump reached to the saturation point because of continuous increase of Na+ion , at that time no more extra glucose can be bound to the pump and at this point pump will work maximally so this will form the plateau.

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