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harpo10 harpo10
wrote...
13 years ago
I need help with the following:  Neutral Face


1. A cell, located in between extracellular fluid and the gut lumen, contains transporters that mediate passive transport. Assume glucose does not have a charge, and that the action of these transporters is not influenced by the cell's membrane potential. An event in this organism raises the glucose conc. in the extracellular fluid rapidly such that it is higher than the concentration of the glucose inside the cell or in the gut lumen. The only way glucose can move from the gut lumen to the extracellular space (and vice versa) is through the cell.

A) After glucose reaches equilibrium, what are the relative conc. of glucose in the gut lumen, inside the cell, and in the extra cellular space? Explain. (My thoughts: the net relative conc. should be equal in al three because the system is in a state of equilibrium due to the tendency of high to low diffusion)

B) Assume you can convert this transporter into a pump that transports glucose against its conc gradient using the energy of ATP. Diagram the basic steps (Neutral Face)






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Replies
wrote...
Educator
13 years ago Edited: 13 years ago, bio_man
A. I would think so too, since it is at equilibrium and that is moves passively.

B. This would be primary active transport. I drew a diagram for you to show this (below). Reply back if you need more explanation.



<a rel="nofollow" href="https://http://bcs.whfreeman.com/thelifewire/content/chp05/0502s.swf" target="_blank">https://http://bcs.whfreeman.com/thelifewire/content/chp05/0502s.swf</a>


Bio_man 8)
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harpo10 Author
wrote...
13 years ago
Okay I get what you have in the diagram, but how specifically would the steps go?
wrote...
Educator
13 years ago Edited: 13 years ago, bio_man
ATP binds to the ATP-binding site of the transmembrane protein. It is catalytically converted to ADP, where the energy converts the inactive glucose binding site to one that can freely accept glucose molecules - as you can tell, the binding site on the top illustration is triangular while the binding site on the bottom is squarish. Once the glucose binds, it is pumped into the area of higher concentration. The pumping of one glucose molecule subsequently changes the conformation to one that can no longer accept glucose, until a fresh supply of energy (ATP) is used.
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