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The London Institute for Contemporary Christianity

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The Wonder and the Sorrow of PCR Tests

PCR tests are a fact of life for most of us at the moment. As a biologist who was doing this procedure long before most people had heard of it, I take secret delight in people’s use of the acronym. Let me open the laboratory door and share the wonders it conceals.

The swab that you, or someone else, pokes down your throat and up your nose goes into a tube containing a little liquid. That liquid is then heated or mixed with a chemical to kill any live virus particles, then purified to get rid of every part of the virus except RNA.

The test is actually RT-PCR, the first step being Reverse Transcription by an enzyme that converts any RNA present into DNA. Multiple copies of that DNA are then made using the Polymerase Chain Reaction. Reverse transcription produced one half of a DNA helix, like one side of an unzipped zip. The enzyme DNA Polymerase is a little like the zipper, except as well as zipping up it also manufactures the other half of the zip, using DNA subunits that have been added to the tube.

This process works because a bit like a zip, the two sides of the DNA helix are mirror images of each other. If that new helix is unzipped, DNA polymerase can then make a new strand on both sides.

The beauty of PCR is in its simplicity. Multiple rounds of heating (which melts the DNA helix strands apart) and cooling (which allows the enzyme to make new DNA) produce more and more mirror-image DNA strands.

Scientists often have stories to tell about the wonders they study, or make use of, in the lab. Sadly, if this particular process works it means that there was COVID-19 in the sample and someone may be about to become quite ill.

Do you live with similar tensions in your own work? Perhaps you sell a fantastic product that most people in the world can’t afford. Maybe you love taking care of people, but your job only exists because your clients live with great physical or mental challenges.

For the Psalmists, a relationship with God was forged in the confusing space where the struggles of life mingled with praise for creation and trust in him. How can we learn from these inspired ancient writers this week, celebrating the wonders we experience in our work while also lamenting the world’s brokenness, praying for healing and justice?

Ruth Bancewicz 
Church Engagement Director at the Faraday Institute of Science and Religion



  1. A fascinating post demonstrating the contradictions so many of us face in our work. Great to hear the background to how PCRs work too. Thank you for explaining it.
    For me, as a writer, it’s the tension between being a more reflective type and yet also needing to promote my work, which seems somehow at odds with the Jesus-way.
    The Psalms are indeed a space where confusion is blended with praise. I need to read them more often. Thank you for your thoughts on this.

    By Deborah Jenkins  -  28 Jan 2022

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