PCR stands for polymerase chain Reaction. It will amplify the specific segment of the DNA that makes a million copies of DNA molecule. This technique is widely employed in the areas of molecular biology, research and diagnostic.

It has three following steps: This process is carried in a thermocycler, which is a machine that can rapidly heat and cool samples.

Denaturation:

The DNA sample is heated up to (95 deg Celsius), which causes the double stranded DNA separated into single strands.

Annealing:

Primers must be added to the complementary sequence of the targeted DNA fragment. primers are short pieces of single-stranded DNA that are specific for the sequence we want to amplify. In this step, the temperature must be lowered into (50-60 deg C). It allows the primers to anneal or bind to the complementary sequence of the DNA.

Extension:

DNA polymerase enzyme should be added to the DNA fragment so that it will extends the primers, synthesizing a new DNA strand complementary to the target DNA fragment. The temperature is raised into around 72 deg C.

These steps (1-3) are repeated for the many cycles to get the increased amount of the amplified target DNA fragment.

Applications:

DNA cloning:  

PCR can be used to create copies of genes or DNA that can be inserted into plasmid or vector for future manipulation.

Genetic testing:

PCR can be used to detect mutations in genes, which can be helpful in diagnosing genetic diseases.

DNA sequencing:

PCR is often used to amplify DNA fragments before they are sequenced.

Forensic science:

PCR can be used to analyze DNA evidence from crime scenes.

COVID-19 testing:

RT-PCR is the most common type of test used to diagnose COVID-19. It detects the presence of viral RNA in a patient’s respiratory sample.