Diffusion Lab Report

Topics: Diffusion, Osmosis, Semipermeable membrane Pages: 8 (2635 words) Published: October 23, 2010
The importance of this computerized simulation study was to gain an understanding of the processes that account for the movement of substances across the plasma membrane, and to indicate the driving force for each. This may also be applied to the study of transport mechanisms in living membrane-bounded cells. Also, understanding of which way substances will move passively through a deferentially permeable membrane depending on the concentration differences. We used PhysioEx software to examine diffusion. In these experiments we used different sized membranes as well as NaCl, urea, glucose, albumin, powdered charcoal, and KCl. The step by step process was used by the software so that we could see the different kinds of reactions. According to the data found, we found that with high molecular weight compounds are too large to penetrate the molecular weight cut off pores and no simple diffusion can occur. So it seemed like the easiest way for a solute to pass through a semipermeable membrane was, if it either was small enough to pass or had some sort of carrier protein that helped it along. We expected to see continuous results that do not have much difference in the five experiments that are to be performed. Experiments were conducted in order to gain a better understanding of a cell’s selectively permeable membrane and the passive processes of simple and facilitated diffusion. The purpose of this experiment was to make observations based on the computerized simulation providing information on the passage of water and solutes through semipermeable membranes, which may be applied to the study of transport mechanisms in living membrane-bounded cells. We hypothesized that when the sucrose concentration will change, the mass will also change.

A molecular composition of a plasma membrane is selective about what can passes through it. There are two methods of transport which can occur through the plasma membrane. To be discussed first, the method of transportation is called active transport which uses ATP (glucose) or energy to move substances through the membrane. Secondly, the method of a passive transport does not require the use of ATP (glucose) or energy. During passive transport (or gradient), molecules are moved through the membrane of the cell by the imbalance of molecules and or pressure between the inside and outside of the cell. Simple diffusion, facilitated diffusion, osmosis, and filtration are all types of passive transports. In a living human body the cells use diffusion as the important transport process through its selectively permeable membrane. Diffusion is defined as the movement of particles from an area of higher concentration to an area of lower concentration, which results because of the random movement of particles. Osmosis is the diffusion of water into and out of a selectively permeable membrane. Because of the selectively permeable membrane, nothing but water and other very small particles can be diffused through osmosis. Molecules use their kinetic energy as the motivating force in diffusion. Facilitated diffusion occurs when molecules are too large to pass through a membrane or are unable to be dissolved into the lipid bi-liar. The process or act is when the carrier protein molecule located in the membrane combine with solute and transports them down the concentration gradient. Established gradients are due to the pressure of molecules on each side of the membrane’s wall. Also the membrane’s pore size and amount of pores depends on the amount of molecules and fluids in the filtrate. Another type of passive transport that is not a selective process is called filtration. Furthermore, the process filtration is when the water and solutes pass through a membrane (such as a dialysis membrane) from an area of higher hydrostatic (fluid) pressure into an area of lower hydrostatic pressure; which means that water and solutes would pass through a selectively permeable...
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