The Na+/Glucose symport is present on the apical surface of absorptive epithelial cells in our intestinal lining. When glucose concentrations inside the lumen of our intestine are low, the symport will [Select] [Select] This transport is driven by [Select] export glucose out of the cells of our intestinal lining. be unable to transport glucose. import glucose into the cells of our intestinal lining.
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Step 1: The Na+/Glucose symport is a secondary active transport system that uses the electrochemical gradient of sodium ions (Na+) to drive the transport of glucose across the cell membrane. Show more…
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On the apical membrane of enterocytes, glucose moves up its concentration gradient as it enters the cell from the intestinal lumen. If the chemical ouabain, which shuts down sodium-potassium pumps, is present, glucose is no longer absorbed across the apical membrane. Therefore, glucose is moving across the apical membrane of enterocytes by secondary active transport.
Dominador T.
The Na+/glucose symport transports glucose from the lumen of the small intestine into cells lining the lumen. Transport of 1 glucose molecule is directly coupled to the transport of 1 Na+ ion into the cell. 1 Na+out + 1 glucoseout → 1 Na+in + 1 glucosein Assume the following conditions at 37 °C: [Na+]in = 12 mM, [Na+]out = 145 mM, [glucose]out = 28 μM, and Δψ = -72 mV (inside negative). (a) What is ΔG for transport of Na+ from outside to inside under these conditions? (b) What is the upper limit for [glucose]in under these conditions? (c) Which of the two hypothetical symports shown below (A or B) would achieve the highest concentration of [glucose]in under the conditions described above? Briefly explain your choice. A: 1 Na+out + 2 glucoseout → 1 Na+in + 2 glucosein B: 2 Na+out + 1 glucoseout → 2 Na+in + 1 glucosein
Madhur L.
Describe the symport process by which cells lining the small intestine import glucose. What ion is responsible for the transport, and what two particular, features facilitate the energetically favored movement of this ion across the plasma membrane?
Sri K.
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