Discussion and Conclusion:
During Lab 1A, the data suggests what molecules can and cannot diffuse across a selectively permeable membrane. The coloration showed that the Iodine Potassium Iodide was small enough to pass through the pores of the membrane because the color of this indicator moved from within the beaker to in the bag. Water and glucose moved out because water is small enough to pass through the membrane and the glucose tested positive with the Testape inside the beaker. The glucose at the beginning was only in the bag, so it obviously moved out.
When animal cells are placed in sugar solutions things may be rather different because animal cells do not have cell walls. In very dilute solutions, animal cells swell up and burst: they do not become turgid because there is no cell wall to support the cell membrane. In concentrated solutions, water is sucked out of the cell by osmosis and the cell shrinks. In either case there is a problem. So animal cells must always be bathed in a solution having the same osmotic strength as their cytoplasm. This is one of the reasons why we have kidneys. The exact amount of water and salt removed from our blood by our kidneys is under the control of a part of the brain called the hypothalamus. The process of regulating the amounts of water and mineral salts in the blood is called osmoregulation. My insulin page will tell you more about other homeostatic mechanisms.
The percentage of red blood cells that hemolyze in hypotonic fluids depends on the degree of hypotonicity of the fluid. A plot of % red blood cells hemolyzed (% hemolysis) vs. % NaCl solution is shown below. The data generates a reverse sigmoidal (s-shaped) curve. The plot shows that a very low percentage of normal mammalian red blood cells hemolyze in mildly hypotonic solutions above % NaCl. Significant hemolysis doesn't occur until cells are bathed in stronger hypotonic solutions below %, with % hemolysis rising sharply between and % NaCl to nearly 100%.