MBB 222 Study Guide - Final Guide: Ammonium Sulfate, Affinity Chromatography, Differential Centrifugation

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Fractionation describes the process of separating proteins into different. Fractions based on a particular property including size or charge. Cell homogenate is the product of lysing the cell (includes the membrane and organelles) Centrifugation is a fractionation process that first forms a homogenate by disrupting the cell membrane, causing a dense pellet of heavy material to form at the bottom of the centrifuge tube, with a lighter supernatant above. This process yields several fractions of decreasing density, each still containing 100s of proteins. Each fraction is then assayed/tested for presence of desired protein. In general the smaller the subcellular components, the greater the centrifugal force is required to sediment it. Supernatants are less dense and are usually located above the more dense pellet, which resides on the bottom. Done to obtain a cell fraction enriched in the protein of interest (such as the cytoplasm or membrane fraction)