PCR full form in biology

PCR full form in biology:

  • PCR stands for “Polymerase Chain Reaction.
  • It is a widely used molecular biology technique that allows the rapid amplification of specific DNA segments.

 

Year of Discovery  Inventor name       Why called as PCR
1983 ·        Polymerase Chain Reaction (PCR) was invented by Kary Mullis.

·        He was a biochemist working at Cetus Corporation, a biotechnology company.

·        The name Polymerase Chain Reaction was given to this technique because it reflects the key process in this technique, where DNA polymerase enzyme is used to amplify specific DNA sequences.

 

Biography of Kary Mullis

 

Year         

 

                               Event
December 28, 1944

 

         

·        Kary Banks Mullis was born in Lenoir, North Carolina, USA.
1979   

 

  

·        He joined Cetus Corporation (later acquired by Hoffmann-La Roche) as a DNA chemist.
1983   

 

 

·        Invented the Polymerase Chain Reaction (PCR) technique, which is a revolutionary DNA amplification method.
1986  

 

 

·        His PCR invention was recognized and published in the scientific journal “Science.”
1993  

 

 

·        Awarded with the Nobel Prize in Chemistry for his invention of PCR.
1998  

 

·        Mullis published his autobiography “Dancing Naked in the Mind Field,” where he shared insights into his life and scientific journey
2019   

 

 

·        Kary Mullis passed away on August 7, 2019, in Newport Beach, California, USA, at the age of 74.

 

Steps involve in PCR

Steps

 

Description
Step1.     Denaturation ·        Heating of the DNA sample to around 94-98°C.

·        This step separates the two strands of the double-stranded DNA, breaking the hydrogen bonds between them.

·        The DNA becomes single-stranded.

Step2.

Annealing

·        Cool the sample to around 50-65°C.

·        DNA primers (short, single-stranded DNA sequences) bind to complementary sequences on each DNA strand.

·        Primers act as starting points for DNA synthesis in the next step.

Step 3.

Extension

·        Raise the temperature to around 72°C.

·        A heat-stable DNA polymerase (e.g., Taq polymerase) synthesizes new DNA strands starting from the primers.

·        The polymerase adds nucleotides to the 3′ end of the primers, extending the DNA strands in the 5′ to 3′ direction.

Step 4.

Cycling

·        Steps 1 to 3 are repeated for multiple cycles (typically 20-40 cycles).

·        Each cycle doubles the amount of target DNA, resulting in exponential amplification of the desired DNA segment.

Step 5.

Final Extension

·        After the last cycle, the reaction is typically held at 72°C for a short period to ensure completion of any remaining DNA synthesis.

·        This step helps to ensure that all the DNA strands are fully extended.

Step 6.

Cooling

The reaction is cooled to a low temperature (e.g., 4°C) for storage or further analysis.

The final PCR product, which is a large number of copies of the target DNA, is ready to use.

 

Applications of  PCR

 

Applications

 

Description
DNA Amplification

 

 

·        PCR allows the rapid and exponential amplification of a specific DNA segment, generating a large number of copies.

·        It offers excellent specificity, as it amplifies only the targeted DNA sequence with the use of specific primers.

 

 

Forensic Analysis ·        PCR is crucial in forensic analysis,

·        It helps in the identification of individuals through DNA profiling and evidence examination.

 

Non-Invasive Diagnostics ·        In some cases, PCR can diagnose diseases using non-invasive samples like saliva, urine, or blood.

 

Mutation Analysis and Detection ·        PCR is used to analyze genetic mutations and screen for specific mutations associated with genetic disorders.

 

Sensitivity and Specificity ·        PCR is highly sensitive, capable of detecting minute amounts of target DNA in a complex mixture.

 

Rapid Results ·        PCR provides quick results, allowing researchers to obtain DNA amplification within a few hours.

 

Versatility ·        PCR has versatile applications, including DNA cloning, gene expression analysis, genetic testing, and diagnostics.

 

Minimal Sample Requirement ·        PCR requires only a small amount of DNA as a template, conserving precious or limited samples for further analysis.
Identification of Infectious Agents ·        PCR aids in identifying infectious agents, such as bacteria and viruses thus helps in the diagnosis of infectious diseases.

 

Monitoring Disease Progression ·        PCR allows researchers to track disease progression and treatment response based on changes in target DNA levels.