Contact us :customer@cti-eu.com
Views: 9 Author: vivi Publish Time: 2025-07-01 Origin: Site
In recent years, questions related to PCR (Polymerase Chain Reaction) technology have frequently appeared in the biology section of China's Gaokao (college entrance exam). These questions may ask students to explain the principles of PCR or analyze its role in specific application scenarios. Such questions assess not only students’ understanding of fundamental biological concepts but also their awareness of real-world technological applications.
By exploring these topics, students gain deeper insights into how PCR enables scientists to rapidly amplify specific DNA fragments—revolutionizing fields such as genetics, medical diagnostics, and forensic science. In this post, we’ll provide a brief overview of the fundamentals of PCR technology.
PCR (Polymerase Chain Reaction) is a widely used technique in genomics, molecular biology, and medical research. Invented by American biologist Kary Mullis in 1983, it allows for the rapid amplification of specific DNA sequences under laboratory conditions. PCR has become an essential tool in genetic and genomic research and plays a critical role in forensic identification, disease diagnosis, genetic screening, and research on genetically modified organisms (GMOs).
The core principle of PCR (Polymerase Chain Reaction) is to use a heat-stable DNA polymerase to synthesize large quantities of a specific DNA fragment under carefully controlled temperature conditions. This process relies on the use of primers (short DNA sequences) and template DNA, and it proceeds through a series of temperature-regulated steps: denaturation, annealing, and extension.
PCR essentially mimics the natural process of DNA replication in vitro. To perform a successful PCR reaction, the system must contain the fundamental components required for DNA synthesis:
Template DNA: Contains the target DNA segment to be amplified.
Primers: A pair of short DNA sequences that define the start and end points of the target region.
DNA Polymerase: A heat-resistant enzyme that synthesizes the new DNA strands (e.g., Taq polymerase).
dNTPs (Deoxynucleotide Triphosphates): The building blocks used to assemble the new DNA strands.
Buffer: Provides the optimal chemical environment for the DNA polymerase to function effectively.
01. Denaturation: The first step of PCR involves heating the DNA sample to approximately 94–98°C, which causes the hydrogen bonds between the double-stranded DNA to break. As a result, the DNA unwinds into two single strands. This denaturation process exposes the template strands, making them accessible for primer binding.
02. Annealing：The temperature is then lowered to 55–70°C, allowing the short, single-stranded DNA primers to bind (anneal) to their complementary sequences on the template strands. Primers are specifically designed to match regions flanking the target DNA segment, ensuring the specificity of the PCR reaction.
03. Extension：At around 72°C, the optimal temperature for thermostable DNA polymerase (such as Taq polymerase), the enzyme begins to synthesize new DNA strands. It adds free dNTPs (deoxynucleotide triphosphates) to the primers, extending them along the template strands to create new complementary DNA copies.
By repeating these three steps in cycles—typically 20 to 40 times—the amount of target DNA doubles with each cycle. In a short period, even trace amounts of DNA can be amplified into millions of copies, making it suitable for downstream applications and analysis.
PCR technology has a wide range of applications across various fields, including:
Genetic Diagnosis: Detecting disease-related gene mutations, early screening of hereditary disorders, and identifying viral infections through viral DNA/RNA detection (e.g., HIV, HPV, coronavirus, etc.).
Forensic Identification: Analyzing DNA samples for identity verification, criminal investigations, and paternity testing.
Environmental Monitoring: Detecting microbial DNA in environmental samples to monitor and assess pollution or contamination levels.
Scientific Research: Widely used in gene cloning, gene expression analysis, mutation detection, and other areas of molecular biology and biotechnology.
Mini Centrifuge(MLX-204)
Mini Centrifuge(MLX-200F)
Mini Centrifuge(VM-03U)
