Diffusion Through a Membrane Lab

Topics: Glucose, Starch, Carbohydrate Pages: 4 (937 words) Published: November 2, 2010
Diffusion through a Membrane

Molecules are constantly moving. They move in straight lines unless they are deflected by other molecules or obstacles in their environment. Diffusion is the process by which the collisions between molecules cause them to continually spread apart from each other. Their movement can be described as movement from an area of greater concentration to an area of lower concentration. Diffusion continues until the molecules are equally distributed, that is their concentration is equal throughout the area that contains them. At this point, the molecules continue to move and collide, but their concentration remains the same throughout the area of containment. When certain molecules encounter artificial membranes with pores, they may be able to pass through. If the molecules are small enough to pass through the pores, their movements eventually will cause the concentration of these molecules inside and outside of the membrane to equalize. Living cells are surrounded by a membrane that acts as a selective barrier between the contents of the cell and its environment. The membrane is selectively permeable; it allows some molecules and other particles to enter and exit while blocking others. Even small molecules that could ordinarily pass through may be blocked. There permeability of the membrane can change depending on changes in the internal or external environment of the cell. In this lab, molecules were being tested due to temperature and being combined with others. For one part there were different substances poured into water starch and glucose. During the lab, we created diffusion in the membrane when the molecules were heated they were diffused by spreading farther and farther apart from each other. Molecules are always moving

Materials and Methods
Dialysis tubing
Starch solution
Un-waxed dental floss
Paper towels
Glucose indicator solution
Test tube rack
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