The plasma or cell membrane exhibits ability for the cell to discriminate in its chemical exchanges with its environment and this makes cell membrane fundamental to life. This property can only be possible because of the cell membrane’s selective permeability (Campbell and Reece, 2002). The structure of the membrane can be best illustrated by the fluid mosaic model where the membrane is said to be a fluid structure with various proteins embedded in or attached to a bilayer of phospholipids (Campbell and Reece, 2002). Molecules can be transported through the membrane by means of passive and active transport. Passive transport is just the diffusion of a substance across the membrane while active transport is the movement of substance across the membrane against its concentration or potential gradient with the help of energy input and specific transport proteins (Campbell and Reece, 2002). For the analysis of cell membrane permeability and the mechanism of controlling water, human red blood cell is a convenient specimen through hemolysis experiments ^^^^^. The human RBC osmotic content is about 0.9% NaCl. In hypotonic solutions, the cells swell because of water influx and eventually they hemolyze where cell contents including hemoglobin are released into the medium. This can be indicated by the change from opaque red cell suspension into transparent pink solution. Placing the cells in a medium containing permeating solute particles increases osmotic concentration and results to observable changes. Therefore the purpose of this experiment is to determine the relative permeation rates of different solute particles using hemolysis rates as basis.
Campbell N, and Reece J. 2002. Biology. Pearson Education, Inc., San Francisco, CA, USA.