Related topics: dna

Quick and sensitive identification of multidrug-resistant germs

Researchers from the University of Basel have developed a sensitive testing system that allows the rapid and reliable detection of resistance in bacteria. The system is based on tiny, functionalized cantilevers that bend ...

Sorting out viruses with machine learning

The ongoing global pandemic has created an urgent need for rapid tests that can diagnose the presence of the SARS-CoV-2 virus, the pathogen that causes COVID-19, and distinguish it from other respiratory viruses. Now, researchers ...

Researchers identify new Rickettsia species in dogs

Researchers at North Carolina State University have identified a new species of Rickettsia bacteria that may cause significant disease in dogs and humans. This new yet unnamed species, initially identified in three dogs, ...

Researchers extract DNA from insects embedded in resin

For the first time, Senckenberg scientist Mónica Solórzano-Kraemer, together with lead authors David Peris and Kathrin Janssen of the University of Bonn and additional colleagues from Spain and Norway, successfully extracted ...

Promising new method for producing tiny liquid capsules

Microcapsules for the storage and delivery of substances are tiny versions of the type of capsule used for fish oil or other liquid supplements, such as vitamin D. A new method for synthesizing microcapsules, reported in ...

Universal virus detection platform to expedite viral diagnosis

The quick, accurate detection of a virus on a wide scale is the key to combating infectious diseases such as COVID-19. A new viral diagnostic strategy using reactive polymer-grafted, double-stranded RNAs will serve as a pre-screening ...

New technology can detect antivirus antibody in 20 minutes

Researchers have succeeded in detecting anti-avian influenza virus antibody in blood serum within 20 minutes, using a portable analyzer they have developed to conduct rapid on-site bio tests. If a suitable reagent is developed, ...

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Polymerase chain reaction

In molecular biology, the polymerase chain reaction (PCR) is a technique to amplify a single or few copies of a piece of DNA across several orders of magnitude, generating millions or more copies of a particular DNA sequence. The method relies on thermal cycling, consisting of cycles of repeated heating and cooling of the reaction for DNA melting and enzymatic replication of the DNA. Primers (short DNA fragments) containing sequences complementary to the target region along with a DNA polymerase (after which the method is named) are key components to enable selective and repeated amplification. As PCR progresses, the DNA generated is itself used as a template for replication, setting in motion a chain reaction in which the DNA template is exponentially amplified. PCR can be extensively modified to perform a wide array of genetic manipulations.

Almost all PCR applications employ a heat-stable DNA polymerase, such as Taq polymerase, an enzyme originally isolated from the bacterium Thermus aquaticus. This DNA polymerase enzymatically assembles a new DNA strand from DNA building blocks, the nucleotides, by using single-stranded DNA as a template and DNA oligonucleotides (also called DNA primers), which are required for initiation of DNA synthesis. The vast majority of PCR methods use thermal cycling, i.e., alternately heating and cooling the PCR sample to a defined series of temperature steps. These thermal cycling steps are necessary to physically separate the strands (at high temperatures) in a DNA double helix (DNA melting) used as the template during DNA synthesis (at lower temperatures) by the DNA polymerase to selectively amplify the target DNA. The selectivity of PCR results from the use of primers that are complementary to the DNA region targeted for amplification under specific thermal cycling conditions.

Developed in 1984 by Kary Mullis, PCR is now a common and often indispensable technique used in medical and biological research labs for a variety of applications. These include DNA cloning for sequencing, DNA-based phylogeny, or functional analysis of genes; the diagnosis of hereditary diseases; the identification of genetic fingerprints (used in forensic sciences and paternity testing); and the detection and diagnosis of infectious diseases. In 1993 Mullis was awarded the Nobel Prize in Chemistry for his work on PCR.

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