Diseases, Conditions, Syndromes

Taming COVID-19 requires urgent search for both vaccine and treatment

Bonnie Robeson, a senior lecturer at the Johns Hopkins Carey Business School, knows what it's like to take part in an urgent race to find a vaccine or treatment for a lethal malady, such as the current effort to contain the ...

Diseases, Conditions, Syndromes

One minute electro-optical coronavirus test developed

Ben-Gurion University of the Negev's Prof. Gabby Sarusi has developed a one-minute electro-optical test of nose, throat or breath samples that will identify both asymptomatic and affected carriers of the COVID-19 virus in ...

Diseases, Conditions, Syndromes

Clinical performance of SARS-COV-2 antibody tests varies

(HealthDay)—The diagnostic specificity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serologic assays varies, and sensitivity is poor during the first 14 days of symptoms, according to a study published ...

Diseases, Conditions, Syndromes

Egypt hospitals near 'critical threshold' in virus fight

Three months after Egypt reported its first novel coronavirus case, medical experts warn the strained healthcare system of the Arab world's most populous nation is nearing a "critical threshold".

Diseases, Conditions, Syndromes

Spain records lowest daily virus toll in a month

Spain recorded 367 people deaths from novel coronavirus over the past 24 hours, the lowest daily number of fatalities in four weeks, the government said on Friday.

Diseases, Conditions, Syndromes

How COVID-19 tests work, and why they're in short supply

One key to stopping the spread of COVID-19 is knowing who has it. A delay in reliable tests and COVID-19 diagnostics in the United States has painted an unreliable picture of just how many people are infected and how the ...

Diseases, Conditions, Syndromes

Artificial intelligence enables COVID-19 lung imaging analysis

For most patients who have died of COVID-19, the pandemic disease caused by a novel coronavirus, the ultimate cause of death was pneumonia, a condition in which inflammation and fluid buildup make it difficult to breathe. ...

page 1 from 12

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.

This text uses material from Wikipedia, licensed under CC BY-SA