During the Membrane Transport laboratory exercise, the glucose solution did not

Question

During the Membrane Transport laboratory exercise, the glucose solution did not cause the red blood cells to lyse (burst) while the urea solution did. What was the reason for this result? A. Both glucose and urea solutions were 300 mM, but the intracellular concentrations of glucose and urea were different. The glucose concentration inside a red blood cell is 300 mM while the urea concentration inside a red blood cell is much less (0-2 mM). Even though both glucose and urea could cross the cell membrane, glucose was at equilibrium and had no concentration gradient pushing it into the cell, while urea did have a concentration force pushing it into the cell. Consequently, there was no net movement of glucose but urea entered the cells, pulling water with it because it is osmotically active, causing the cells to swell and burst. B. The glucose solution was iso-osmotic while the urea solution was hypo-osmotic. Because there were less urea particles outside the cell than there were urea particles inside the cell, water moved into the cell and caused the cell to swell and eventually burst. C. Even though both solution were iso-osmotic, glucose is not an osmotically active molecule like urea. Therefore, even though both glucose and urea diffused across the membrane into the cells, urea pulled water with it causing cells to swell and burst while glucose did not. D. Even though both the glucose and urea solutions were iso-osmotic, the urea solution had a higher concentration than the glucose solution. This higher concentration allowed urea to have a concentration gradient pushing it into the cell. When urea passed into the cell, water to move into the cell with it because urea is osmotically active. Because outside of the cell glucose had a lower concentration than urea, glucose didn't diffuse into the cell E. Even though both the glucose and urea solutions were iso-osmotic, but they had different effects on the red blood cells because of their properties. The concentrations of both glucose and urea outside of the cells were 300 mM, while inside there was very little (if any) glucose or urea, resulting in concentration gradients for both molecules. However, glucose was a big molecule and could not cross the cell membrane, while urea was small molecule that could easily pass into the cell. As urea crossed the membrane into the cell, water followed it because it is osmotically active, causing the cell to swell and burst.

Explanation / Answer

when an RBC is placed in an iso-osmolar solution, usually it should have no effect.

however, an iso-osmolar solution can act as hypotonic, if the solute is able to enter the cell. RBC when placed in an iso-osmotic solution of urea, the urea solution behaves as hypotonic. since, urea that travels down its concentration gradient, pulls water into the cell causing it to burst.

option C.

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