Is This Any Way To Run A City?

The Mystery of Energy Metabolism

The Hidden City Continued

Biologists argue about which came first, metabolism or replication, or in other words, enzymes or DNA. Other biologists try to square the circle by saying, “We can have both at the same time with RNA.” But there is something missing from all three scenarios, without which they won’t get far. Both metabolism and replication require a means to store and transfer energy.

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The structure of AMP, adenosine monophosphate. From Concepts of Biology – 1st Canadian Edition, Chapter 9 Figure 1 Creative Commons

Modern day cells use a molecule called ATP for this process: adenosine triphosphate. It is related structurally to one of DNA’s building blocks: adenine. Compare their structures. Adenine is a base (double ring structure in orange). Add a sugar to it and it becomes adenosine. Add a phosphate to that and you have a nucleotide. Add two more phosphates, and you have ATP. Adenosine triphosphate.

Ho hum you say. What is so interesting about that?

Think of in this way. You have a computer system that stores its information in codes of four instead of two. Not 0s and 1s, but As, Cs, Ts, and Gs. Adenine is the A. One part of the code. Now imagine you take your computer hardware that does the encoding for A, whatever it is, stick a sticky bit on it, and a rechargeable battery, and suddenly you can light campfires and suck the power from light bulbs.