I amplify DNA. Yes, I really do.

by Lorien E. Menhennett

“I trust you.”

That was about the greatest thing my research supervisor, Olga, could have said to me. She was referencing my skills at setting up PCR (polymerase chain reactions). And it’s quite helpful that she trusts me with these reactions, because the work in our lab involves doing quite a bit of PCR.

Not only am I precise and accurate with these reactions, I am also building up my speed. I was setting up 24 tubes of PCR last Thursday, for example. Olga came in to check on me and asked how I was doing. “I’m done,” I told her. “You’re done?” she asked, brows raised in surprise. “Pretty soon you’re going to be a machine!” Another high compliment from a highly intelligent woman with a PhD who can pipette with lightning speed. Compared with my snail’s pace from last summer – when I came in not knowing what a pipette was, and certainly not knowing how to use one – I’ve come a long way.

While those of you familiar with lab protocol likely know what PCR is, most people don’t. I certainly didn’t until last summer, when Olga expertly and succintly explained it to me. It’s quite marvelous, really, how it works. I thought I would take a blog post to explain it, since it’s been such a big part of my lab work lately.

The goal of PCR is to amplify a specific region of DNA. There are three steps in PCR: denaturing, annealing, and elongation. These are fancy, scientific words for breaking apart the entire strand of DNA, using what is called “primers” to bind to the broken-apart DNA, and then employing a special enzyme called taq polymerase to synthesize a copy of the specific DNA region you want. You do this through cycles of heating and cooling to promote these different steps. This yields an exponential amount of the region of DNA you want. Pretty cool, eh?

Here is a visual representation of the process*

The technique was developed in the 1980s, and in the 1990s, its inventors were awarded a Nobel Prize. It’s amazing to me that less than 30 years ago, we did not even have this technology. Science has come such a long way, and I am thrilled to be a part of it.

*This image was downloaded from the online edition of: Molecular Cell Biology. 4th edition. Lodish H, Berk A, Zipursky SL, et al. New York: W. H. Freeman; 2000.
Available on the NCBI bookshelf: Molecular Cell Biology