Finding wheels

        When I was a sophomore taking Biochemistry, one particular event stands out in my memory, perhaps because it was such an odd thing. Our Professor, Dr. X, knew his material very well. Our classroom had nine blackboards stacked in groups of three. As he wrote on one, Professor x would flip a switch and blackboard A would advance upward, then B, then C, following some pattern that only he knew, until at the end of class, having dragged us all through metabolism, he would neatly draw an arrow connecting blackboard I’s reaction with the one on the starting blackboard. He always left me staring at my notes in despair of connecting them.

            But that’s not what I remember about him the best. One day we were having a discussion about the marvelous things that were being found in biology. It was only a decade since the genetic code had been cracked, and the first DNA and the first protein had been sequenced. These were remarkable achievements. The development of the tools that made genetic engineering possible was happening at MIT there and then. I didn’t really realize how momentous it all was. But one thing Dr X said stuck in my brain. He said, “We will find marvelous things in biology because nature is very inventive. But one thing we will never find is a wheel.” Maybe he thought that the wheel was a man-made machine, smooth, round, and designed. Biology was made of bumpy lumpy proteins and was most emphatically not designed. But I speculate. He never gave his reasoning

Let us have a moment of silence to reflect on the dangers of hubris.

Now let me count the ways “unintelligent” nature has made circles, rotors, wheels and gears:

Porins : These proteins are pores in the membrane, holes to let compounds into or out of the cell. Not quite a wheel, they would be an uneven ride. The protein is shown here in three different ways: one showing every chemical bond (stick), one showing a cartoon of the protein’s secondary structure (the way the amino acids associate with one another), and one showing what the surface of the protein would look like to another protein, or a molecule trying to squeeze through its hole. Bacteria and mitochondria both have porins but not apparently of common origin.

ATP synthase : This molecular machine is 98% efficient at using a flow of protons across the inner mitochondrial membrane to change ADP back to ATP. Part of its essential inner structure is the c-ring rotor, shown in yellow. Its ring structure can best be seen in panel B. As protons pass through the inner channel, the ring begins to spin, acting as a rotor. The rotor contacts other proteins in blue on the “stator,” shown on the left in A. This causes a conformational change in the stator, which allows the ADP to ATP reaction to take place. (For a general description of the whole process see this DI video link here) The technical paper describing the structure, and from which this figure is borrowed is

Flagellum: Not just a wheel, but a water-cooled, acid-fueled, rotary motor, capable of up to 17,000 rpm that can reverse directions in one quarter turn. Very much analogous to human motors, it has parts that function as a drive shaft, stator, bushings, gaskets, and the motor itself.

Diatoms:  Well, maybe he didn’t mean whole organisms. But anyway:

A micrograph of the diatom Actinoptychus maculatus

Leaf hopper’s gears: My professor didn’t mention gears, which are even more stupendous. But see for yourself.

Truthfully, no one in the early 1970s had any idea the wonders there were still to discover in biology. And I think it’s safe to say, no one now should think we are ready to declare the riddle of life solved. We can’t even say that we are close to solving it, because we don’t know how much more there is to learn. Let’s let biology show us her wonders. Hubris has a bad name for a reason.

Adapted from a post originally published at Evolution News,


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