The emergence and development of modern cell biology and molecular biology has been greatly accelerated by the development of methods by which organelles and macromolecules of cells have been separated from each other, isolated in pure form. With the help of separation methods, it became possible to study the chemical composition of living matter, the function of cellular organelles, create cell-free systems, and analyze biochemical processes. In this chapter, we briefly discuss the separation methods most commonly used in molecular cell biology, centrifugation, chromatography, and electrophoretic methods.
Centrifugation In cell organelle suspension or macromolecule solutions exposed to multiples of gravity acceleration (g), the dispersed particles settle to varying degrees depending on their size, shape and density. In centrifuges, this is achieved by rotating a metal rotor with a high-performance motor, in which the centrifuge tubes rotate in a fixed position (angular rotor) or assuming a horizontal position during centrifugation (swing-glass rotor). Acceleration of 600,000 × g is also possible in the most powerful ultracentrifuges. Different types of centrifugation can be used for biological purposes.
Types of centrifuges
Differential centrifugation