A variety of compounds including sugars and amino acids pass through the plasma membrane and into the cell at a much higher rate than would be expected on the basis of their size, charge, distribution coefficient, or magnitude of the concentration gradient. The increased rate of transport through the membrane is believed to be facilitated by specific membrane carrier substances [...]
Before we consider several mechanisms responsible for bulk movement of materials into and out of cells, it is important that, what is meant by "inside the cell'' and "outside the cell". The plasma membrane as a more or less continuous smooth sheet en- dosing the cell. In reality, this is an oversimplification, for in most cells the plasma membrane exhibits [...]
Any discussion of the uses of radioisotopes as tracers in cell biology would be incomplete without at least a brief description of autoradiography. The materials and equipment used in this technique differ significantly from those employed in the methods previously described. In autoradiography, the biological sample containing the radioisotope is placed in close contact with a sheet or film of [...]