Polymerase Chain Reaction or PCR is a temperature-based enzymatic process conducted in vitro. This process is also known as “molecular photocopying”. Developed by Kary Mullis in 1983, the principle behind PCR is the enzymatic replication of DNA used to amplify DNA or RNA.

How Does PCR Work?

In PCR, a short segment of template DNA is amplified using a primer.

Once primers bind to the target sequence, DNA polymerase extends the new DNA strands by adding nucleotides in the 5’ to 3’ direction. This cycle of denaturation, annealing, and extension is repeated multiple times, usually 25-35 cycles. Each cycle produces multiple sets of target sequences.

This process helps researchers detect and analyze genetic material even if it is available in very low amounts. So, it is widely used in multiple applications. In this guide, we will discuss the application of PCR test kits.

Quick Question! What Are Primers?

Primers are short, single-stranded sequences of nucleotides that are complementary to the target DNA sequence. These primers act as a starting point for DNA synthesis.

Applications of PCR Test Kits

The following are the areas where PCR test kits are used heavily:

Research

a. Gene Expression Studies

Researchers use reverse transcription PCR (RT-PCR) to study how genes are turned on or off in different cells or under different conditions. In RT-PCR, the RNA is converted into complementary DNA (cDNA), and then the cDNA is amplified to quantify the expression levels of specific genes. This process is essential for cancer research, drug discovery, and developmental biology.

b. Cloning and Genetic Engineering

Scientists use PCR to amplify DNA fragments that they wish to insert into plasmids or other vectors for cloning. These vectors can then be introduced into bacterial or eukaryotic cells for the expression of proteins, gene therapy research, or genome editing using tools like CRISPR. Without PCR, such high-precision manipulations of genetic material would be far more laborious and less efficient.

c. Detection of Mutations and SNPs

The genetic variations can influence disease susceptibility, drug response, and inheritance patterns. So, PCR allows researchers to isolate and analyze these regions of interest with great accuracy. This makes PCR crucial for genetic mapping and population genetics studies.

d. Microbial Identification and Metagenomics

PCR test kits are also used in metagenomics and microbial ecology to amplify ribosomal RNA genes from environmental samples. This specific research helps researchers identify and classify microorganisms in complex ecosystems, like soil, ocean water, or the human gut.

Forensics

a. Fingerprinting

Since fingerprints are different for each person, they can be used to identify suspects, exonerate the innocent, or establish familial relationships. However, at certain times, fingerprints are hard to analyze because of injury or damage.

This is where PCR test kits help forensic experts. PCR can amplify regions of the genome containing short tandem repeats (STRs), which are present in fingerprints, making fingerprint analysis easier.

b. Disaster Victim Identification

Similar to how PCR helps with fingerprints, it is particularly helpful in situations where DNA is present but in very small quantities, such as hair, skin cells, or saliva left at a crime scene.

Due to PCR’s ability to detect even the smallest traces of DNA, it assists forensic experts in identifying victims by comparing recovered DNA to that of relatives or stored medical samples.

Medical and Clinical Diagnostics

a. Infectious Disease Diagnosis

Since PCR can detect the presence of a virus or bacterium by identifying its unique genetic signature, even at very low levels, it is the preferred choice of test kit in infection diagnostics.

Did you know PCR test kits have been widely used during the COVID-19 pandemic to detect SARS-CoV-2 RNA in nasal swabs?

Thanks to their high sensitivity, these are also used to diagnose other viral infections, like HIV, hepatitis B and C, human papillomavirus (HPV), and influenza.

b. Tumor Diagnostics

Another area where the diagnostic abilities of PCR test kits excel is in tumor and cancer diagnostics. This is because PCR can analyze tumor DNA for specific mutations or fusion genes.

This helps researchers not only confirm the presence of cancer but also assess prognosis and create personalized treatment plans accordingly, reducing unnecessary patient exposure to toxic drugs.

c. Genetic Disease Screening

PCR is also used in identifying inherited genetic disorders. Conditions such as cystic fibrosis, sickle cell anemia, and Duchenne muscular dystrophy can be diagnosed early through PCR-based genetic testing. In prenatal diagnostics, PCR allows for the detection of chromosomal abnormalities and genetic mutations in fetal DNA, often obtained through amniocentesis or maternal blood samples.

d. Pharmacogenomics

PCR is also used in pharmacogenomics to identify genetic variations that influence how individuals metabolize medications. By understanding a patient’s genetic profile, healthcare providers can prescribe drugs that are more effective and less likely to cause adverse reactions.

The Bottom Line

PCR test kits have revolutionized the fields of research, diagnostics, and forensic science. Their ability to amplify minute amounts of genetic material with accuracy and speed makes them indispensable tools in modern laboratories.

From gene expression studies and cloning to diagnosing infectious diseases and identifying crime victims, PCR applications span across disciplines. As molecular biology continues to evolve, PCR will remain a cornerstone technology, opening new frontiers in personalized medicine, biotechnology, and environmental science.

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