glucose and sodium can be co-transported across a membrane through the Na+/Gluco
ID: 55706 • Letter: G
Question
glucose and sodium can be co-transported across a membrane through the Na+/Glucose Co-transporter. this transporter is used to transport glucose into the cells of the gut epithelium as depicted in the diagram to the right.
if you can accurately answer and explain the following questions (A, B, and C) it would be much appreciated, I'm struggling with this material. the rest of the question is the photo.
lomework 4-17 points (2 estra credin) Due in claxs 10/7/15 Name trampeet glucose anto cells of the gpn spibeliarm as depicted in the diagram to the rigt Remember the concestration of glucusc in the gst lumes is low relative so the intrauellular glucose concentration ia gue epithelial cells, while the soncentration of Na within the gat lmen in high relisive to the intracellalar Nai concestntions in gut epitheial celsa Aj Is the transpont of plucse into cells of the gut epithellums an exampke of active or parssive trarspont? u point B) The Na'iglooe co-tansporter is aln) uniporter sy mperter/antiparter. (cirele the comoct verm) (1 poiet) You decide to soudy the Na ilusose co-iearsporter in reconstinuted lipid vestches in which the only proteis present is the Navghuscse oo-tanspomer, In your esperimenial system the that the extracellular portion of the protein is on the outside of the vesicles, and the iniracellular portion of the protein faces the inside of the vesicles is oriented so Using these vesicles you set up an experiment in which the Nat concentration is high outside the vesicles and low inside the vesicles, and the glucose ooncentrution is low outside the vesicles and high inside. C) Uinder these experimental conditions: (ü)Which molecules will be transported and (i) in which direction will they move? Brielly explain your answer. (3 polats)Explanation / Answer
The epithelial cells lining kidney tubules, which have an architecture similar to that of intestinal epithelial cells, reabsorb glucose from the blood filtrate that is the forming urine and return it to the blood. In the first part of a kidney tubule, the epithelial cells transport glucose against a relatively small glucose concentration gradient. These cells utilize a second type of Na+/glucose symport protein — a one-Na+/one-glucose symporter, which has a high transport rate but cannot transport glucose against a steep concentration gradient. At the intracellular Na+ concentration and membrane potential depicted in Figure 15-9, this symporter can generate an intracellular glucose concentration 100 times that of the extracellular medium (here the forming urine). In the latter part of a kidney tubule, however, the epithelial cells take up the remaining glucose against a more than 100-fold glucose concentration gradient. To accomplish this, these cells contain in their apical membrane the same two-Na+/one-glucose symporter found in intestinal epithelial cells. The two types of Na+/glucose symport proteins are similar in amino acid sequence, predicted structure, and mechanism but have evolved to transport glucose under different conditions.
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