Water Potential and Osmosis
Introduction
Molecules are constantly in motion due to thermal energy. Therefore, the molecules will move around and bump into each other. Because of this, molecules tend to spread out evenly into available space in a process called diffusion. Diffusion is the random process of molecules moving from areas of high concentration to low concentration, thus requiring no energy. Many of the substances that enter or leave the cell do so through diffusion.
Osmosis, a type of diffusion, is the movement of water across a selectively permeable membrane. In osmosis, water diffuses across the area of lower solute concentration to that of higher solute concentration until the solute concentrations of the environment and the cell are equal. Tonicity, which is the ability of a solution to gain or lose water due to osmosis, results in an environment that is isotonic, hypertonic, or hypotonic. A hypotonic solution has a lower solute concentration than the cell so water moves into the cell causing the cell to swell. A hypertonic solution has a higher solute concentration than the cell so water moves out of the cell and into the solution causing the cell to shrink. In an isotonic solution, concentration of solutes is equal inside and outside the cell so water moves across the membrane in both directions retaining the same cell size. In all three environments, water will move until it reaches equilibrium. In this experiment, the solution in which the dialysis tube was placed in is determined by the mass in grams of the dialysis tube before put in the solution compared to the mass after. If the mass increases, the dialysis tube was in a hypotonic solution since water went in the dialysis tube. If the mass decreases, the dialysis tube was in a hypertonic solution since water left the cell. If the mass stays the same, then the dialysis tube was in an isotonic solution since water went in and out of the dialysis tube at equal rates.
The polarity of water allows water to dissolve many
Molecules are constantly in motion due to thermal energy. Therefore, the molecules will move around and bump into each other. Because of this, molecules tend to spread out evenly into available space in a process called diffusion. Diffusion is the random process of molecules moving from areas of high concentration to low concentration, thus requiring no energy. Many of the substances that enter or leave the cell do so through diffusion.
Osmosis, a type of diffusion, is the movement of water across a selectively permeable membrane. In osmosis, water diffuses across the area of lower solute concentration to that of higher solute concentration until the solute concentrations of the environment and the cell are equal. Tonicity, which is the ability of a solution to gain or lose water due to osmosis, results in an environment that is isotonic, hypertonic, or hypotonic. A hypotonic solution has a lower solute concentration than the cell so water moves into the cell causing the cell to swell. A hypertonic solution has a higher solute concentration than the cell so water moves out of the cell and into the solution causing the cell to shrink. In an isotonic solution, concentration of solutes is equal inside and outside the cell so water moves across the membrane in both directions retaining the same cell size. In all three environments, water will move until it reaches equilibrium. In this experiment, the solution in which the dialysis tube was placed in is determined by the mass in grams of the dialysis tube before put in the solution compared to the mass after. If the mass increases, the dialysis tube was in a hypotonic solution since water went in the dialysis tube. If the mass decreases, the dialysis tube was in a hypertonic solution since water left the cell. If the mass stays the same, then the dialysis tube was in an isotonic solution since water went in and out of the dialysis tube at equal rates.
The polarity of water allows water to dissolve many