Have you ever tried pulling computer cords out of a box, only to become frustrated by the tangled mess? Cells face the same problem every time they replicate our DNA. When DNA strands are duplicated, the unreplicated portion becomes twisted and “supercoiled” — threatening to terminate replication before it’s complete. How do our cells solve this knotty dilemma? The answer is the family of enzymes known as topoisomerases.
Thank You to Topoisomerases
Basically, if you’re alive, you can thank topoisomerases. They are the subject of the fifth molecular machine animation produced by Discovery Institute. It joins our other animations showcasing key cellular operations such as ATP synthase (energy production), kinesin (intracellular transport), the bacterial flagellum (cell motility), and protein synthesis (featured in Journey Inside the Cell). The video premiered at our Insiders Briefing last August, but wasn’t shown in its entirety. Now you can see the full video here:
Let’s briefly explore one of these crucial enzymes, topoisomerase II, which is the video’s specific focus. The topoisomerase II enzyme is designed to untangle knots and supercoils in DNA strands which arise during replication and transcription. It does this by grabbing two tangled DNA segments, holding one steady while it breaks the other segment in two, and then passing the first segment through the break. The second segment is then reconnected, and the two DNA segments are released, having been successfully untangled. Without topoisomerases, chromosomes would become an impossible mess, making DNA replication, transcription, and cell duplication impossible.
Not by Accident
The carefully orchestrated untangling activity of topoisomerase II doesn’t happen by accident. This enzyme is a molecular machine that only works because its amino acid sequence is highly specified to provide a special shape and structure necessary for its function. In other words, topoisomerase enzymes contain high levels of complex and specified information — a hallmark of intelligent design.