The synthesis principle of PCR, what is the principle of PCR technology

Denaturation of template DNA: After the template DNA is heated to about 94 after a certain polymerase chain reaction, the template DNA double-stranded or double-stranded DNA formed by PCR amplification is dissociated and made into a single strand, so that it can bind to the primers and prepare for the next round of reaction; Annealing (refolding) of template DNA and primers: After the template DNA is heated and denatured into a single strand, the temperature drops to about 40 60, and the primers bind to the complementary sequences of the template DNA single strand; Extension of primers:

Under the action of DNA polymerase, the DNA template-primer conjugate synthesizes a new semi-retained replication strand complementary to the template DNA strand according to the principle of base pairing and semi-retained replication, and repeats the three processes of cyclic denaturation-annealing-extension of the DNA strand to obtain more "semi-retained replication strands", and this new strand can become the template for the next cycle. It takes 2 to 4 minutes to complete each cycle, and 2 to 3 hours amplify the gene to be amplified by millions of times.

To put it simply, it's DNA replication, and you need a detailed process.

Fundamentals of PCR Technique:

This technique relies on the enzymatic synthesis of DNA polymerases in the presence of template DNA, primers, and four deoxyribonucleotides. DNA polymerases use single-stranded DNA as a template to initiate synthesis with the help of a small piece of double-stranded DNA, which is partially double-stranded by combining one or two synthetic oligonucleotide primers with a complementary sequence in the single-stranded DNA template.

At a suitable temperature and environment, DNA polymerase adds deoxymononucleotide to the 3-OH end of primer, which is used as a starting point to extend along the template5 3 direction to synthesize a new DNA complementary strand.

Application of PCR technology:

The first clinical application of PCR technology began with the detection of genetic mutations in sickle cell and thalassemia.

The most valuable application area of PCR in medical laboratory science is the diagnosis of infectious diseases. Theoretically, PCR can detect as long as one pathogen is present in the sample.

PCR technology can not only effectively detect gene mutations, but also accurately detect the expression of oncogenes, which can be used for early diagnosis, typing, staging and prognosis of tumors.

There is a sentence in the textbook: PCR uses the "principle of thermal denaturation of DNA" to control the depolymerization and binding of double strands by controlling the temperature.

PCR, also known as polymerase chain reaction, has an amplification step consisting of three sequential steps. (1) Denaturation: It is the use of DNA denaturation at high temperature in vitro, and the dissociation of double-strands into single-strands; (2) Annealing:

At low temperatures, primers and single strands are combined according to the principle of base complementary pairing; (3) Extension: The process of readjusting the temperature to the optimal reaction temperature of DNA polymerase (about 72 °C), and DNA polymerase synthesizes complementary strands along the direction of phosphoric acid to five-carbon sugar (5'-3'). Repeat ("loop") these three steps 25-35 times to obtain an exact copy of the target DNA exponentially.