Thermal cycler

PCR Machine

Baby Blue - a prototype polymerase chain reaction (PCR), c 1986. (9663810586)

Primitive PCR machine for scrap

A Multi Bay PCR Machine

Thermal cycler

A thermal cycler, also known as a PCR machine or DNA amplifier, is a laboratory apparatus most commonly used to amplify segments of DNA via the polymerase chain reaction (PCR). The device has a thermal block with holes where tubes holding the PCR reaction mixtures can be inserted. The cycler then raises and lowers the temperature of the block in discrete, pre-programmed steps.

History

The development of the thermal cycler was a significant advancement in the field of molecular biology. The invention of the polymerase chain reaction (PCR) by Kary Mullis in 1983 necessitated the creation of a machine that could precisely control the temperature changes required for the reaction. Early thermal cyclers were manually operated, but modern devices are fully automated and programmable.

Components

A typical thermal cycler consists of several key components:

• Thermal block: This is the part of the machine that holds the PCR tubes and changes temperature.
• Peltier element: This component allows rapid heating and cooling of the thermal block.
• Control panel: Used to program the temperature cycles.
• Lid: Often heated to prevent condensation on the tube caps.

Function

The primary function of a thermal cycler is to facilitate the polymerase chain reaction (PCR). The PCR process involves repeated cycles of heating and cooling to denature the DNA, anneal primers, and extend the DNA strands. The typical steps in a PCR cycle are:

• Denaturation: Heating the reaction mixture to around 94-98°C to separate the DNA strands.
• Annealing: Cooling the mixture to 50-65°C to allow primers to bind to the DNA template.
• Extension: Raising the temperature to around 72°C to allow the DNA polymerase to synthesize the new DNA strand.

Applications

Thermal cyclers are used in a variety of applications, including:

• Genetic research: Amplifying DNA for sequencing and cloning.
• Medical diagnostics: Detecting genetic mutations and pathogens.
• Forensic science: Amplifying DNA from crime scene samples.
• Agricultural biotechnology: Genotyping plants and animals.

Advancements

Modern thermal cyclers have advanced features such as gradient blocks, which allow for the optimization of annealing temperatures, and real-time PCR capabilities, which enable the quantification of DNA in real-time.

Related Pages

• Polymerase chain reaction
• DNA polymerase
• Kary Mullis
• Molecular biology
• Genetic research
• Medical diagnostics
• Forensic science
• Agricultural biotechnology