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Centrifugation is the first step in most fractionations. Through low-speed centrifugation, cell debris may be removed, leaving a supernatant preserving the contents of the cell. Repeated centrifugation at progressively higher speeds will fractionate homogenates of cells into their components.
The first isolation of deoxyribonucleic acid (DNA) was done in 1869 by Friedrich Miescher. [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 ...
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 ...
The pure solid crystals are then separated from the remaining liquor by filtration or centrifugation. Recrystallization : In analytical and synthetic chemistry work, purchased reagents of doubtful purity may be recrystallised, e.g. dissolved in a very pure solvent, and then crystallized, and the crystals recovered, in order to improve and/or ...
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 ...
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.
DNA preparation is another common application for pharmacogenetics and clinical diagnosis. DNA samples are purified and the DNA is prepped for separation by adding buffers and then centrifuging it for a certain amount of time. The blood waste is then removed and another buffer is added and spun inside the centrifuge again.
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.