Polymerase Chain Reaction Biotech Basics Series Topic 1

Added: 2026-05-17

[00:00:00]Let me ask you, what if you have a very little sample, but you want to perform many experiments on that? How will you do that?

[00:00:08]So, let me give you a very good answer.

[00:00:10]It is possible because a very famous scientist, Kary Mullis, invented and discovered a process called PCR in 1983, for later which he got awarded Nobel Prize in Chemistry after 10 years in 1993.

[00:00:26]And you may ask, what is this process?

[00:00:28]So, the full form is polymerase chain reaction, in which you basically extend your sample of DNA, so that you can perform many experiments on that. And this process is mainly consisted of three steps. First is denaturation, in which the temperature usually stays around 94 to 95°C, and in this step basically we break the bonds between double-stranded DNA and make it two single strands.

[00:00:54]Next step is annealing, in which the temperature is cooled down a little bit, and in that the temperature stays usually between 50 to 65°C.

[00:01:04]And you may ask, what is this process?

[00:01:05]So, in this process we add forward and reverse primer on the DNA template.

[00:01:10]That's it. The next and last step is elongation, basically also called extension. In this, we add an enzyme called DNA Taq polymerase, which is a thermostable enzyme, because after so much so much heat changes, you might need a thermostable thing to maintain your DNA, do not break it. So, that is what it does. And it is acquired from Thermus aquaticus bacteria, which is such a good thing. Okay?

[00:01:36]This step basically elongates the DNA.

[00:01:40]In the annealing step, we added the primer, and that just helps to extend the DNA template. So, you could have many more samples. And this step usually you can run it for 25 to 35 times, and it takes around 2 to 4 hours. And this is done by a machine called thermal cycler which made all the work very easy.

[00:02:00]And you may ask where do we apply PCR?

[00:02:02]In many, many, many types of different things in forensic science, agriculture, genetic research, and many more.

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