Thermal cycler PCR

Thermal cycler PCR (Polymerase Chain Reaction) is an important experimental equipment used to amplify specific DNA fragments. It achieves rapid DNA replication and amplification by repeating the denaturation, annealing and extension steps over multiple temperature cycles. This article will introduce in detail the structure and working principle of the thermal cycler.

1. Composition and structure of thermal cycler

The structure of thermal cycler PCR mainly includes the following parts:

1. Control system

The control system is the core part of the thermal cycler. It includes a microprocessor and a series of software to set and adjust various parameters of the temperature cycle. Through the control system, researchers can accurately set the temperature and time of denaturation, annealing, and extension to ensure efficient PCR reactions.

2. Temperature module

The temperature module is a key component to achieve temperature control. It usually consists of multiple independent heating and cooling units, each unit can independently adjust the temperature. The high precision and rapid reaction capability of the temperature module are the key to ensuring the accuracy of PCR reactions.

3. Sample tank

The sample tank is where the PCR reaction tubes are placed. Modern thermal cyclers usually adopt a multi-well plate design, which can process multiple samples at the same time and improve experimental efficiency. The material of the sample tank usually has good thermal conductivity to ensure the uniformity and stability of the sample temperature.

4. Display and operation interface

The display and operation interface is used to display the current temperature, time and cycle status, and allows the user to enter and modify parameters. Most thermal cyclers are equipped with a touch screen or push-button interface, making operation easier and more intuitive.

2. Working principle of the composition structure

1. Transsexual stage

During the denaturation stage, double-stranded DNA in the sample melts at high temperatures (usually 94-98°C) to form single-stranded DNA. This step requires precise temperature control to ensure that the DNA is completely melted but not degraded.

2. Annealing stage

The annealing stage reduces the temperature to approximately 50-65°C, allowing the primers to bind to the target DNA sequence. The temperature setting at this stage is crucial, because too high a temperature will cause the primers to be unable to bind effectively, and too low a temperature may cause non-specific binding.

3. Extension stage

During the extension phase, the temperature rises to 72°C and DNA polymerase begins to extend from the 3’ end of the primer to synthesize a new DNA strand. The temperature and time of this step also need to be precisely controlled to ensure optimal activity and reaction rate of the DNA polymerase.

4. Repeat the cycle

The above three stages constitute a complete PCR cycle, which usually needs to be repeated 20-40 times. The thermal cycler's control system performs this process automatically, ensuring accurate temperatures and times for each cycle.

3. Advantages of thermal cycler PCR

Thermal cycler PCR offers many advantages in modern molecular biology research:

1. Efficiency

Thermal cyclers can amplify large amounts of DNA in a short time, greatly improving the efficiency and yield of experiments.

2. Accuracy

By precisely controlling temperature and time, the thermal cycler can ensure high specificity and sensitivity of PCR reactions and reduce the generation of non-specific products.

3. Repeatability

Modern thermal cyclers are usually highly automated and standardized, resulting in good repeatability and consistency of experimental results.

4. Conclusion

Thermal cycler PCR achieves rapid and accurate DNA amplification through precise composition and precise working principles. Its efficiency, accuracy and reproducibility make it occupy an important position in molecular biology research and medical diagnosis. With the continuous advancement of technology, the application scope of thermal cycler PCR will become more and more extensive, bringing more convenience and breakthroughs to scientific research and medical health.