What are the 5 key basic reagents used in PCR?

PCR (Polymerase Chain Reaction) is an amplification technique that is widely used to generate large amounts of a specific DNA segment using a small amount of starting material, which could be a DNA template or target sequence). There are 5 key basic reagent required to complete a PCR reaction:

DNA/RNA template

A DNA or RNA template is the first reagent required to complete a PCR reaction. Different PCR techniques require different templates. Conventional PCR uses DNA templates while RNA templates are used for performing RT-qPCR. A DNA template for replication can be of any DNA source including complementary DNA (cDNA), genomic DNA (gDNA) or plasmid DNA.

Using sufficient quantities of high quality DNA or RNA templates are critical to optimizing the efficiency of PCR.

DNA polymerase

DNA polymerases are essential for replicating the target DNA and is another reagent used in all PCR reactions. The DNA polymerases used in PCR must be able to work under high temperatures of about 70 °C. This is because the first phase of the reaction involves separating DNA strands, which is done at a high temperature of about 90 °C.

Taq polymerase is the most commonly used DNA polymerase for PCR because of its relatively high thermostability. 

Primers

PCR primers serve as a DNA synthesis starting point for DNA/RNA polymerase. These primers are short strands of nucleotides – either DNA or RNA - of approximately 15–30 bases. PCR primers are complementary to the template DNA and bind to sequences that flank the region of interest in the template DNA.

Deoxynucleotide triphosphates (dNTPs)

Deoxynucleotide triphosphates (dNTPs) are the building blocks of nucleic acids. They consist of four basic nucleotides - dATP, dCTP, dGTP, and dTTP. DNA polymerases need a sufficient supply of dNTPs to synthesize DNA. DNA synthesis cannot proceed with dNTPs.

PCR buffers

PCR buffers provide a suitable chemical environment for DNA polymerase to perform efficiently. They help maintain a stable pH during PCR and ensure that the reaction is conducted under optimal conditions.