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Centrifugation is a mechanical process which involves the use of the centrifugal force to separate particles from a solution according to their size, shape, density, medium viscosity and rotor speed. [1]
DNA extraction is the process of isolating DNA from the cells of an organism isolated from a sample, typically a biological sample such as blood, saliva, or tissue. It involves breaking open the cells, removing proteins and other contaminants, and purifying the DNA so that it is free of other cellular components.
A centrifuge is a device that uses centrifugal force to subject a specimen to a specified constant force - for example, to separate various components of a fluid. This is achieved by spinning the fluid at high speed within a container, thereby separating fluids of different densities (e.g. cream from milk) or liquids from solids.
Differential centrifugation, on the other hand, does not utilize a density gradient, and the centrifugation is taken in increasing speeds. The different centrifugation speeds often create separation into not more than two fractions, so the supernatant can be separated further in additional centrifugation steps.
This mixture is then centrifuged. Because the phenol:chloroform mixture is immiscible with water, the centrifuge will cause two distinct phases to form: an upper aqueous phase, and a lower organic phase. The aqueous phase rises to the top because it is less dense than the organic phase containing the phenol:chloroform.
Human blood after separation by centrifugation. Plasma (upper layer), buffy coat (middle, white-colored layer) and erythrocyte (red blood cell) layer (bottom) can be seen. The buffy coat is commonly used for DNA extraction, [4] with leukocytes providing approximately 10 times more concentrated sources of nucleated cells. [5]
Buoyant density of the majority of DNA is 1.7g/cm 3 [3] which is equal to the density of 6M CsCl solution. [citation needed] Buoyant density of DNA changes with its GC content. The term "satellite DNA" refers to small bands of repetitive DNA sequences with distinct base composition floating above (A+T rich) or below (G+C rich) the main ...
DNA sequencing; Expression cloning; Fluorescence in situ hybridization; Lab-on-a-chip; Comparison of nucleic acid simulation software; Northern blot; Nuclear run-on assay; Radioactivity in the life sciences; Southern blot; Differential centrifugation (sucrose gradient) Toeprinting assay; Several bioinformatics methods, as seen in list of RNA ...