PCR(Polymerase Chain Reaction): The Fascinating Technique of DNA amplification

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PCR stands for Polymerase Chain Reaction. It is a widely used molecular biology technique that allows scientists to amplify or make millions of copies of a specific segment of DNA. This process enables the detection and analysis of even tiny amounts of DNA.

On this page

1. Discovery of PCR
2. Advancements and Development
3. Commercialization and Application
4. Real-Time PCR (qPCR)
5. Digital PCR
6. Advancements in Enzymes and Techniques
7. Prerequisites of Polymerase Chain Reaction
8. Working Principle of Polymerase Chain Reaction
9. How to perform a PCR?
10. Types of PCR
11. 10 Applications of PCR
12. 9 Uses of PCR in disease diagnosis

Discovery of PCR

In 1983, while working at the Cetus Corporation, a biotechnology company, Mullis made a significant breakthrough that would change the landscape of DNA analysis. The idea for PCR struck him during a late-night drive from his laboratory in California to his home in Mendocino. Mullis realized that he could repeatedly amplify a specific segment of DNA using a simple, repetitive process involving heating and cooling.

The key to his innovation was the use of synthetic DNA primers – short, single-stranded DNA sequences that are complementary to the sequences flanking the target DNA region. These primers act as starting points for DNA synthesis and are crucial for the PCR process.

Advancements and Development

The initial discovery of PCR was groundbreaking, but it was not without challenges. One significant obstacle was the heat stability of the DNA polymerase enzyme, which was necessary for the denaturation and extension steps of the PCR process. Traditional DNA polymerases were easily denatured at the high temperatures required for denaturation (around 94-98°C).

To address this issue, scientists searched for naturally occurring DNA polymerases with high-temperature resistance. They found Thermus aquaticus, a bacterium living in hot springs, which had a DNA polymerase enzyme (Taq polymerase) that could withstand the repeated heating and cooling cycles of PCR. The discovery of Taq polymerase was a crucial breakthrough that made PCR a practical and widely used technique.

Commercialization and Application

The commercialization of PCR technology began in the mid-1980s. In 1985, Cetus Corporation filed a patent for PCR, which sparked legal battles over the ownership of the technology. Eventually, the patent rights were sold to Hoffman-La Roche, a pharmaceutical company, further fueling the widespread adoption and development of PCR technology.

The early 1990s saw the expansion of PCR applications, including DNA sequencing, genetic testing, forensic analysis, and the study of infectious diseases. The technique’s versatility and efficiency made it an indispensable tool in molecular biology laboratories worldwide.

Real-Time PCR (qPCR)

Another significant advancement came with the development of real-time PCR (quantitative PCR or qPCR). Traditional PCR methods required the analysis of the amplified DNA after the amplification process was complete, which could be time-consuming and labor-intensive. Real-time PCR, on the other hand, allows scientists to monitor the DNA amplification in real-time as it happens, providing valuable quantitative data about the initial amount of DNA in the sample.

Digital PCR

In the early 2000s, digital PCR (dPCR) improved over traditional PCR and qPCR methods. Digital PCR partitions the DNA sample into thousands of tiny reactions, each with either zero or one DNA target molecule. By counting the positive reactions, researchers can determine the absolute quantity of the target DNA in the original sample with higher precision and sensitivity.

Advancements in Enzymes and Techniques

Over the years, researchers have continued to improve PCR technology by developing more robust DNA polymerases and fine-tuning temperature cycling protocols. Additionally, new variations of PCR have been introduced, such as nested PCR, multiplex PCR, reverse transcription PCR (RT-PCR), and quantitative reverse transcription PCR (qRT-PCR), each with specific applications.

Today, PCR has become an indispensable tool in various scientific fields, including genetics, biotechnology, medicine, forensics, and environmental science. The ongoing advancements and innovations in PCR techniques have made it an essential part of modern research and have facilitated significant breakthroughs in our understanding of genetics and the molecular basis of various diseases.

Prerequisites of Polymerase Chain Reaction

Performing a Polymerase Chain Reaction (PCR) requires several prerequisites to ensure accurate and successful results. These prerequisites include:

1. DNA Sample: A DNA sample containing the target region of interest is the primary requirement for PCR. This DNA can be extracted from various sources, such as blood, tissues, cells, or purified DNA from previous experiments.

2. Primers: Specific DNA primers are short, single-stranded DNA sequences that are complementary to the sequences flanking the target DNA region. These primers are essential for initiating DNA synthesis during the PCR process. Designing appropriate primers is crucial for the success of PCR.

3. DNA Polymerase: A heat-stable DNA polymerase enzyme is required for extending the primers and synthesizing new DNA strands during PCR. The most commonly used DNA polymerase for PCR is Taq polymerase, derived from the bacterium Thermus aquaticus.

4. Nucleotides (dNTPs): Deoxyribonucleotide triphosphates (dNTPs) are the building blocks of DNA. They are the individual units that are added to the growing DNA strands during PCR.

5. Buffer Solution: PCR is typically carried out in a buffer solution that provides the optimal conditions for the DNA polymerase to function efficiently. The buffer also contains salts that help stabilize the DNA and maintain the appropriate pH level.

6. Thermal Cycler: A thermal cycler, also known as a PCR machine, is a specialized instrument that can rapidly change temperatures. The thermal cycler is essential for cycling through the different temperature stages of PCR, including denaturation, annealing, and extension.

7. Thermocycling Program: A well-defined thermocycling program specifies the time and temperature for each step of the PCR process. The program typically consists of cycles of denaturation, annealing, and extension, and the number of cycles depends on the target DNA and the desired level of amplification.

8. Positive and Negative Controls: Including positive and negative controls in the PCR experiment is crucial for validating the results. A positive control contains a known sample with the target DNA, ensuring that the PCR process is functioning correctly. A negative control lacks the target DNA and helps detect any potential contamination or false-positive results.

9. PCR Tubes/Plates: The DNA sample and PCR reagents are mixed in PCR tubes or plates placed in the thermal cycler during the PCR process.

10. Pipettes and Tips: Accurate and precise pipetting equipment, such as micropipettes and tips, are essential for measuring and transferring small volumes of reagents during the PCR setup.

11. Contamination Prevention Measures: To avoid contamination, it is crucial to work in a clean and dedicated PCR workspace. Using separate sets of pipettes and avoiding direct contact with DNA samples are some measures to prevent contamination.

12. Knowledge of PCR Protocol: Familiarity with the specific PCR protocol, including primer sequences, annealing temperatures, and cycle numbers, is essential for setting up the PCR reaction correctly.

By ensuring these prerequisites are met, researchers can perform PCR reliably and achieve accurate and reproducible results for various applications, ranging from basic research to diagnostic testing.

Working Principle of Polymerase Chain Reaction

1. Denaturation

Denaturation is the first step in the Polymerase Chain Reaction (PCR) process. It involves heating the DNA sample to a high temperature to separate the double-stranded DNA into two single strands. This is a crucial step in PCR, as it prepares the DNA template for the subsequent steps of amplification.

Role of Denaturation

The purpose of denaturation is to break the hydrogen bonds between the complementary base pairs (adenine-thymine and cytosine-guanine) that hold the two strands of the DNA double helix together. By disrupting these bonds, the double-stranded DNA unwinds and separates into two individual single-stranded DNA molecules.

Temperature for Denaturation

Denaturation is typically carried out at a high temperature between 94 to 98 degrees Celsius (°C). This high temperature is necessary to ensure complete separation of the DNA strands, as the hydrogen bonds require significant energy to break.

Enzymes and Chemicals

The main components involved in denaturation are:

1. DNA Template: The DNA sample that contains the target region to be amplified serves as the template for the PCR reaction. This DNA can be extracted from various sources, such as blood, tissues, cells, or purified DNA from previous experiments.

2. DNA Polymerase: Although the DNA polymerase enzyme is essential for the subsequent steps of PCR, it is not directly involved in the denaturation step. The most commonly used DNA polymerase for PCR is Taq polymerase, which is derived from the bacterium Thermus aquaticus. Taq polymerase is heat-stable and can withstand high denaturation temperatures without denaturing itself.

3. Buffer Solution: The PCR reaction is carried out in a buffer solution that provides the optimal conditions for the DNA polymerase to function efficiently. The buffer also contains salts that help stabilize the DNA and maintain the appropriate pH level.

Denaturation Process

During the denaturation step, the PCR reaction mixture is heated to the specified denaturation temperature. At this high temperature, typically around 94 to 98°C, the hydrogen bonds between the base pairs of the DNA double helix are broken, causing the double-stranded DNA to unwind and separate into two single strands.

Once denaturation is complete, the DNA template is in a single-stranded state, and it is ready for the next step of PCR, which is annealing. During annealing, specific DNA primers bind to the complementary sequences on the single-stranded DNA, setting the stage for the subsequent amplification of the target DNA region.

In summary, denaturation is the first step in PCR, involving the heating of the DNA sample to separate the double-stranded DNA into two single strands. This prepares the DNA template for the subsequent steps of the PCR process, enabling the amplification of the target DNA region.

2. Annealing

Annealing is the second step in the Polymerase Chain Reaction (PCR) process, following denaturation. During annealing, the temperature of the PCR reaction is lowered, allowing specific DNA primers to bind to the complementary sequences on the single-stranded DNA template. This step is essential for initiating DNA synthesis during PCR and is a crucial part of the amplification process.

Role of Primers:

DNA primers are short, single-stranded DNA sequences that are designed to be complementary to the sequences flanking the target DNA region. In the annealing step, the PCR reaction mixture contains an excess of these primers, allowing them to find and bind to their specific target sites on the single-stranded DNA.

Temperature for Annealing

The temperature for the annealing step typically ranges between 50 to 65 degrees Celsius (°C), depending on the melting temperature (Tm) of the DNA primers. The Tm is the temperature at which half of the primer molecules are bound to the DNA template, and it is calculated based on the primer’s length and nucleotide composition.

Enzymes and Chemicals

During annealing, two main components are critical:

1. DNA Primers: As mentioned earlier, DNA primers are short, single-stranded DNA sequences that are complementary to the target DNA region. They act as starting points for DNA synthesis during PCR.

2. DNA Polymerase: The DNA polymerase enzyme is responsible for extending the DNA primers and synthesizing new DNA strands during PCR. The most commonly used DNA polymerase for PCR is Taq polymerase, which is derived from the bacterium Thermus aquaticus. Taq polymerase is heat-stable and can withstand the high temperatures required for denaturation and still function efficiently during the annealing and extension steps.

Chemicals and Buffer Solution

The PCR reaction mixture also contains deoxyribonucleotide triphosphates (dNTPs), which are the building blocks of DNA. These nucleotides are required for the DNA polymerase to add to the growing DNA strands.

The PCR reaction is carried out in a buffer solution that provides the optimal conditions for the DNA polymerase to function efficiently. The buffer also contains salts that help stabilize the DNA and maintain the appropriate pH level.

Annealing Process

During the annealing step, the PCR reaction mixture is briefly cooled to the specified annealing temperature. At this temperature, the DNA primers anneal to the complementary target sequences on the single-stranded DNA template.

Once the primers are bound to their target sites, the DNA polymerase extends the primers by adding nucleotides to the 3′ end of each primer. This process results in the synthesis of new DNA strands, complementary to the single-stranded DNA template.

After the annealing step is complete, the PCR reaction progresses to the next stage, which is the extension (elongation) step. During extension, the temperature is raised to the optimal range for the DNA polymerase, allowing it to synthesize new DNA strands using the annealed primers as templates. This leads to the amplification of the target DNA region, resulting in millions of copies of the original DNA sequence.

3. Elongation

Elongation, also known as extension, is the third step in the Polymerase Chain Reaction (PCR) process, following denaturation and annealing. During elongation, the temperature of the PCR reaction is raised to the optimal range for the DNA polymerase enzyme, allowing it to synthesize new DNA strands complementary to the single-stranded DNA template. This step is crucial for amplifying the target DNA region and generating multiple copies of the original DNA sequence.

Role of Elongation

In the elongation step, the DNA polymerase uses the annealed DNA primers as starting points to initiate DNA synthesis. It extends the primers by adding nucleotides to the 3′ end of each primer, generating new DNA strands that are complementary to the single-stranded DNA template.

Temperature for Elongation

The temperature for the elongation step typically ranges between 68 to 72 degrees Celsius (°C), depending on the optimal temperature for the specific DNA polymerase being used. This temperature range ensures that the DNA polymerase functions efficiently to add nucleotides to the growing DNA strands.

Enzymes and Chemicals

The main components involved in elongation are:

1. DNA Polymerase: The DNA polymerase enzyme is the key player in the elongation step. The most commonly used DNA polymerase for PCR is Taq polymerase, which is derived from the bacterium Thermus aquaticus. Taq polymerase is heat-stable and can withstand the denaturation step’s high temperatures. During elongation, it efficiently synthesizes new DNA strands using the annealed DNA primers as templates.

2. Nucleotides (dNTPs): Deoxyribonucleotide triphosphates (dNTPs) are the building blocks of DNA. They are the individual units (adenine, thymine, cytosine, and guanine) that the DNA polymerase adds to the growing DNA strands during elongation.

3. Buffer Solution: The PCR reaction is carried out in a buffer solution that provides the optimal conditions for the DNA polymerase to function efficiently. The buffer also contains salts that help stabilize the DNA and maintain the appropriate pH level.

Elongation Process

During the elongation step, the PCR reaction mixture is heated to the specified elongation temperature (typically between 68 to 72°C). At this temperature, the DNA polymerase extends the DNA primers by adding complementary nucleotides to the 3′ end of each primer.

The elongation process results in the synthesis of new DNA strands that are complementary to the single-stranded DNA template. As the elongation step progresses through multiple cycles of denaturation, annealing, and elongation, the target DNA region is amplified exponentially, resulting in millions of copies of the original DNA sequence.

Once the elongation step is complete, the PCR reaction is typically subjected to additional cycles of denaturation, annealing, and elongation, depending on the desired level of amplification. The number of cycles may vary based on the starting amount of DNA, the application of the PCR, and the sensitivity of the detection method used to analyze the PCR products.

In summary, elongation is the third step in PCR, involving the addition of nucleotides by the DNA polymerase to extend the DNA primers and synthesize new DNA strands during the amplification process. It plays a crucial role in generating multiple copies of the target DNA region, making PCR an essential tool in various scientific applications, including genetic research, diagnostics, and forensic analysis.

How to perform a PCR?

Performing PCR requires careful preparation and adherence to specific steps to ensure accurate and successful results. Here’s a step-by-step guide for students on how to perform PCR:

Step 1: Gather Materials:
Collect all the necessary materials and reagents for PCR, including:

• PCR machine (thermal cycler)
• PCR tubes or plates
• DNA sample containing the target region to be amplified
• Forward and reverse DNA primers specific to the target region
• DNA polymerase (e.g., Taq polymerase)
• Deoxyribonucleotide triphosphates (dNTPs)
• Buffer solution for PCR
• Sterile, nuclease-free water
• Micropipettes and tips
• Thermal cycler protocol or program

Step 2: Set Up the PCR Reaction:
Calculate the required volumes of each component for the number of PCR reactions you plan to perform and prepare the PCR reaction mixture in a sterile environment. A typical PCR reaction mixture consists of:

• DNA template (e.g., genomic DNA or cDNA)
• Forward and reverse primers (usually at a final concentration of 0.1 to 1.0 μM each)
• DNA polymerase (as recommended by the manufacturer)
• dNTPs (concentration usually around 200 μM each)
• Buffer solution for PCR (provided with the DNA polymerase)
• Sterile water to bring the total reaction volume to the desired amount (e.g., 25 μL)

Step 3: Add PCR Reaction Mixture to PCR Tubes:
Carefully transfer the PCR reaction mixture to the PCR tubes or plates using sterile micropipettes and tips. Be mindful of avoiding cross-contamination between samples.

Step 4: Close the PCR Tubes or Seal the PCR Plate:
Ensure the PCR tubes are securely capped, or the PCR plate is properly sealed with an adhesive film or plate sealer to prevent evaporation during PCR.

Step 5: Place PCR Tubes or Plates in the Thermal Cycler:
Open the thermal cycler and place the PCR tubes or plate into the designated wells or slots of the thermal cycler block.

Step 6: Run the PCR Program:
Set up the thermal cycler program based on the specific PCR requirements, including the denaturation temperature, annealing temperature, extension temperature, and the number of cycles. Start the PCR program and let the thermal cycler perform the denaturation, annealing, and extension steps for the specified number of cycles.

Step 7: Analyze PCR Products:
After the PCR is complete, you can analyze the PCR products using various methods, such as agarose gel electrophoresis, DNA sequencing, or real-time PCR, depending on the experimental objectives.

Step 8: Interpret Results:
Interpret the PCR results based on the specific objectives of your experiment. Determine whether the target DNA was successfully amplified and the number of amplified products, if applicable.

Step 9: Troubleshooting (If Necessary):
If the PCR results are unexpected, review the experimental steps, primers, and PCR conditions to identify potential issues. Adjust the PCR protocol accordingly and repeat the experiment if necessary.

Remember to always follow good laboratory practices, including proper pipetting techniques, maintaining sterile conditions, and preventing cross-contamination to ensure the accuracy and reliability of your PCR results.

Types of PCR

There are several different types of PCR (Polymerase Chain Reaction) techniques that have been developed to suit various research and diagnostic needs. Some of the most commonly used types of PCR include:

1. Conventional PCR: This is the standard PCR technique that includes three main steps: denaturation, annealing, and elongation. It is used to amplify and detect specific DNA regions in a sample and is the foundation for many other PCR variations.

2. Real-Time PCR (qPCR): Also known as quantitative PCR, real-time PCR allows the detection and quantification of the amplified DNA in real-time as the reaction progresses. It provides a measure of the starting DNA amount and is used for gene expression analysis, viral load determination, and other quantitative applications.

3. Reverse Transcription PCR (RT-PCR): RT-PCR is used to convert RNA into complementary DNA (cDNA) before proceeding with the standard PCR amplification. It is widely used for gene expression studies and for detecting RNA viruses.

4. Nested PCR: Nested PCR involves two sets of primers that target different regions of the same DNA. In the first round, one set of primers amplifies a larger DNA segment. Then, a second round of PCR using a different set of primers amplifies a smaller target within the first PCR product. Nested PCR increases specificity and sensitivity in detecting low-abundance DNA targets.

5. Multiplex PCR: This technique allows simultaneous amplification of multiple target DNA regions using multiple primer sets within a single PCR reaction. It helps analyze multiple genes or pathogens in a single sample.

6. Touchdown PCR: Touchdown PCR involves a gradual reduction of the annealing temperature during the initial cycles of PCR. This helps to enhance specificity by reducing non-specific amplification before using the standard annealing temperature for the remaining cycles.

7. Hot Start PCR: In Hot Start PCR, the reaction is initially kept at a lower temperature to prevent non-specific primer binding, which could lead to false amplification. The DNA polymerase is only activated after the initial denaturation step, enhancing specificity and reducing background noise.

8. Digital PCR (dPCR): Digital PCR partitions the DNA sample into thousands of individual reactions, each containing zero or one target DNA molecule. The number of positive reactions is then counted to determine the absolute quantity of the target DNA, providing high precision and sensitivity.

9. Asymmetric PCR: Asymmetric PCR uses an excess of one primer over the other to preferentially amplify one strand of the target DNA. It is useful for obtaining single-stranded DNA for various applications, such as DNA sequencing or probe labeling.

10. Colony PCR: Colony PCR involves directly amplifying DNA from bacterial colonies without the need for DNA extraction. It is commonly used for screening recombinant DNA clones.

Each type of PCR technique has its unique advantages and applications, making PCR an incredibly versatile tool in various fields, including genetics, medical diagnostics, biotechnology, and forensics. Researchers can choose the appropriate type of PCR based on their specific experimental requirements and desired outcomes.

10 Applications of PCR

Polymerase Chain Reaction (PCR) has revolutionized various scientific fields due to its versatility and ability to amplify specific DNA regions. Some of the key applications of PCR in different fields include:

1. Genetics and Genomics:

PCR is extensively used in genetic research and genomics to amplify and study specific genes or DNA sequences. It enables the identification of genetic mutations, genetic profiling, and gene expression analysis. PCR-based techniques like RT-PCR, qPCR, and multiplex PCR play crucial roles in understanding gene functions, genetic disorders, and genetic diversity among populations.

2. Medical Diagnostics:

PCR is a cornerstone in medical diagnostics for detecting and identifying infectious agents, including bacteria, viruses, and parasites. It is used for diagnosing diseases like HIV, hepatitis, tuberculosis, and COVID-19. Real-time PCR enables rapid and accurate detection of pathogens and has become essential for disease diagnosis and monitoring in clinical laboratories.

3. Forensics:

PCR has transformed forensic science by enabling the analysis of minute amounts of DNA evidence from crime scenes. It is used in DNA fingerprinting, paternity testing, and identifying suspects or victims in criminal investigations. The sensitivity of PCR allows forensic scientists to analyze degraded or trace DNA samples, even from old or degraded biological materials.

4. Biotechnology and Genetic Engineering:

PCR plays a vital role in various biotechnological applications. It is used in recombinant DNA technology to amplify DNA fragments for cloning into vectors, generating genetically modified organisms (GMOs), and producing recombinant proteins through PCR-based expression systems.

5. Evolutionary Biology and Phylogenetics:

PCR is employed in evolutionary studies to analyze DNA sequences and trace the evolutionary relationships between species. It helps researchers understand the genetic ancestry and evolutionary history of organisms, including humans.

6. Environmental Science:

PCR is used in environmental science to detect and quantify microorganisms in environmental samples. It helps assess microbial diversity, monitor pollution levels, and study microbial communities in various ecosystems.

7. Food Safety and Quality Control:

PCR is employed in food safety to detect foodborne pathogens, allergens, and genetically modified organisms in food products. It is also used to monitor food processing and identify sources of contamination in the food industry.

8. Paleogenetics and Archaeology:

PCR is used in paleogenetics to analyze ancient DNA from archaeological remains and fossils. It helps uncover the genetic history of extinct species, ancient humans, and historical populations, providing valuable insights into the past.

9. Veterinary Medicine:

In veterinary medicine, PCR is used to diagnose infectious diseases in animals, identify disease-causing agents, and study animal genetics.

10. Environmental DNA (eDNA) Studies:

PCR is utilized in eDNA studies to detect and analyze DNA fragments shed by organisms into their environment. It aids in monitoring species’ presence and distribution in aquatic and terrestrial ecosystems.

These applications represent only a fraction of the diverse uses of PCR in various scientific disciplines. PCR continues to evolve, with new variants and techniques continually being developed, expanding its utility and impact across different fields of research and industry.

9 Uses of PCR in disease diagnosis

PCR (Polymerase Chain Reaction) is used in various diagnostic tests to detect and identify specific DNA or RNA sequences. Its sensitivity, specificity, and ability to amplify small amounts of genetic material make it a valuable tool for diagnosing various diseases and infections. Some of the diagnostic tests where PCR is commonly used include:

1. Infectious Disease Testing:

PCR is extensively used to diagnose infectious diseases caused by bacteria, viruses, and parasites. It can detect the genetic material of pathogens in patient samples, allowing for rapid and accurate identification. PCR-based tests are widely used for diagnosing diseases like COVID-19, HIV, hepatitis, influenza, tuberculosis, malaria, and many others.

2. Genetic Disorder Testing:

PCR plays a crucial role in diagnosing genetic disorders caused by specific mutations or deletions in DNA. It is used for identifying disease-causing mutations, carrier screening, and prenatal testing for genetic conditions.

3. Cancer Testing:

PCR is employed in cancer diagnostics to detect specific genetic mutations or chromosomal rearrangements associated with certain types of cancer. It can help identify the presence of cancer cells, assess disease progression, and determine treatment strategies.

4. Paternity and Relationship Testing:

PCR-based DNA profiling is used for paternity testing and determining biological relationships between individuals. It compares specific DNA regions to establish familial relationships accurately.

5. Forensic DNA Analysis:

PCR is used extensively in forensic science for DNA profiling and identifying suspects or victims in criminal investigations. It helps analyze biological evidence collected from crime scenes and match it to potential suspects.

6. Microbial Identification:

PCR is employed in clinical microbiology to identify specific bacterial, viral, or fungal pathogens responsible for infections. It aids in guiding appropriate antimicrobial treatment.

7. Foodborne Pathogen Detection:

PCR is used in food safety testing to identify and quantify foodborne pathogens, such as Salmonella, E. coli, and Listeria, in food products.

8. Veterinary Diagnostics:

PCR is utilized in veterinary medicine to diagnose infectious diseases in animals and detect specific pathogens in veterinary samples.

9. Environmental and Water Quality Testing:

PCR is used in environmental science to detect and quantify microorganisms in environmental samples, helping assess water quality and monitor pollution levels.

PCR-based diagnostic tests have become essential tools in medical laboratories and research institutions worldwide. They offer sensitive and reliable methods for detecting a wide range of diseases and conditions, enabling early diagnosis, timely treatment, and better patient outcomes.

Disclaimer: This article is for education purposes only. It introduces the basic concepts behind a Polymerase chain reaction. To perform a PCR one must consult an expert in the field of molecular biology.