Direction and Concentration Gradients

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Direction and concentration gradients
Bradley Benton
ABSTRACT
In this experiment, we will investigate the effect of solute concentration on osmosis. A semi‐permeable membrane (dialysis tubing) and sucrose will create an osmotic environment similar to that of a cell. Using different concentrations of sucrose (which is unable to cross the membrane) will allow us to examine the net movement of water across the membrane. INTRODUCTION

A major determinant of diffusion in a biological system is membrane permeability. Small, uncharged molecules pass through cellular membranes easily, while most and/or charged molecules cannot pass through the membrane. The movement of water across a selectively permeable membrane, like the plasma membrane of the cell, is called osmosis. Osmosis occurs when a membrane separates solutions of different concentrations. The membrane allows the solvent to pass through, but not the solutes. Ultimately, membrane selectivity and the movement of water in and out of the cell regulate the concentration of intracellular material. Remember, a solution contains two or more substances (solutes) that have been dissolved by a solvent. In the context of a cell, the intracellular and extracellular fluids are the solvents which contain dissolved material (solutes). As solute concentration increases, solvent concentration decreases. MATERIALS AND METHODS

In this experiment, we will investigate the effect of solute concentration on osmosis. A semi‐permeable membrane (dialysis tubing) and sucrose will create an osmotic environment similar to that of a cell. Using different concentrations of sucrose (which is unable to cross the membrane) will allow us to examine the net movement of water across the membrane. In this experiment, we will investigate the effect of solute concentration on osmosis. A semi‐permeable membrane (dialysis tubing) and sucrose will create an osmotic environment similar to that of a cell. Using different concentrations of sucrose...
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