DNA amplification is the production of multiple copies of a piece of DNA thereby increasing a gene or chromosomal region frequency. Amplification can occur naturally or artificially. Polymerase chain reaction (PCR) is a biochemical method commonly used for artificial DNA amplification. Artificial amplification makes it possible to generate vast amounts of DNA from a single strand, allowing analysis of extremely small samples.
Selective amplification of nucleic acid, such as DNA or RNA. Repeated thermal cycling is used to generate millions of copies of DNA using heating and cooling cycles to denature the template, anneal the primers to the template and then extension of extend the sequence by the polymerase enzyme. Nucleotides complementary to the template are coupled to the primer, making a double stranded DNA molecule as the enzyme moves along the DNA strand.
An amplification method where multiple copies of a single circular template are generated at isothermal temperature by the highly processive Phi 29 polymerase.
Common causes of gene amplifications include retrotransposition event, aneupoidy, replication slippage, polyploidy and ectopic recomination.
In the presence of free nucleotides and primers, DNA amplification is achieved by denaturing (separating) the double stranded DNA into single strands, using high temperature or enzymatically (e.g. using strand displacement polymerase like Phi 29). At the right annealing temperatures, the primers attach to the complementry single strand DNA template, forming a double strand. Then the polymerase attaches to this double stranded region and moves along the single stranded DNA segment, reading its code and assembling a copy by matching each of the four nitrogen bases: Adenine (A), Thymine (T), Guanine (G) and Cytosine (C) to the original structure. This process makes an identical double stranded DNA molecule as it extends along.
Multiple displacement amplification (MDA) is an isothermal, enzymatic process where phi29 polymerase is used in a strand-displacing amplification to amplify both either linear or circular DNA templates from as few as fentogram concentration, directly from biological samples or as purified DNA.