Biochemistry of Cells

Biochemistry is the study of the chemical constituents of cells and how they are altered during the cell's metabolic reactions. To understand how the cell works as a whole, it is important to understand each component of the cell and its function, thus comprehending its role in the biochemistry of the entire cell. While other lab exercises allow the student to isolate and study one component of the cell, the purpose of this lab is to break down the cell into several components and perform simultaneous assays to determine the constituents. This objective is achieved through the use of differential centrifugation as a separation technique. Separation of cell components using differential centrifugation depends upon differences in size, shape and density that result in different velocities of sedimentation. Organelles with a high sedimentation rate will collect on the bottom of the tube when centrifuged at low speeds. By increasing the gravitational force (g force) and spin time used to pellet cell components, students can isolate different organelles and study them individually. The centrifugation instructions given in this lab are for use with a standard clinical centrifuge, or an SS34 centrifuge rotor, as indicated. However, if you are not using one of these rotors, use the following formula to determine the angular velocity to use for your rotor: