Free The Violinist's Thumb: And Other Lost Tales of Love, War, and Genius, as Written by Our Genetic Code by Sam Kean

transfer RNA with CCG will stick. And when it does stick, the ribosome unloads its amino acid cargo.
    At this point the transfer RNA leaves, the messenger RNA shifts down three spots, and the process repeats. A different triplet is exposed, and a different transfer RNA with a different amino acid docks. This puts amino acid number two in place.Eventually, after many iterations, this process creates a string of amino acids—a protein. And because each RNA triplet leads to one and only one amino acid being added, information should (should) get translated perfectly from DNA to RNA to protein. This same process runs every living thing on earth. Inject the same DNA into guinea pigs, frogs, tulips, slime molds, yeast, U.S. congressmen, whatever, and you get identical amino acid chains. No wonder that in 1958 Francis Crick elevated the DNA → RNA → protein process into the “Central Dogma” of molecular biology. *
    Still, Crick’s dogma doesn’t explain everything about protein construction. For one thing, notice that, with four DNA letters, sixty-four different triplets are possible (4 × 4 × 4 = 64). Yet all those triplets code for just twenty amino acids in our bodies. Why?
    A physicist named George Gamow founded the RNA Tie Club in 1954 in part to figure out this question. A physicist moonlighting in biology might sound odd—Gamow studied radioactivity and Big Bang theory by day—but other carpetbagging physicists like Richard Feynman joined the club as well. Not only did RNA offer an intellectual challenge, but many physicists felt appalled by their role in creating nuclear bombs. Physics seemed life destroying, biology life restoring. Overall, twenty-four physicists and biologists joined the Tie Club’s roster—one for each amino acid, plus four honorary inductees, for each DNA base. Watson and Crick joined (Watson as official club “Optimist,” Crick as “Pessimist”), and each member sported a four-dollar bespoke green wool tie with an RNA strand embroidered in gold silk, made by a haberdasher in Los Angeles. Club stationery read, “Do or die, or don’t try.”

    RNA Tie Club members sporting green wool ties with gold silk RNA embroidery. From left, Francis Crick, Alexander Rich, Leslie E. Orgel, James Watson. (Courtesy of Alexander Rich)
    Despite its collective intellectual horsepower, in one way the club ended up looking a little silly historically. Problems of perverse complexity often attract physicists, and certain physics-happy club members (including Crick, a physics Ph.D.) threw themselves into work on DNA and RNA before anyone realized how simple the DNA → RNA → proteins process was. They concentrated especially on how DNA stores its instructions, and for whatever reason they decided early on that DNA must conceal its instructions in an intricate code—a biological cryptogram. Nothing excites a boys’ club as much as coded messages, and like ten-year-olds with Cracker Jack decoder rings, Gamow, Crick, and others set out to break this cipher. They were soon scribbling away with pencil and paper at their desks, page after page piling up, their imaginations happily unfettered by doing experiments. They devised solutions clever enough to make Will Shortz smile—“diamond codes” and “triangle codes” and “comma codes” and many forgotten others. These were NSA-ready codes, codes with reversible messages, codes with error-correction mechanisms built in, codes that maximized storagedensity by using overlapping triplets. The RNA boys especially loved codes that used equivalent anagrams (so CAG = ACG = GCA, etc.). The approach was popular because when they eliminated all the combinatorial redundancies, the number of unique triplets was exactly twenty. In other words, they’d seemingly found a link between twenty and sixty-four—a reason nature just
had to
use twenty amino acids.
    In truth, this was so much numerology. Hard biochemical facts soon deflated the code breakers and proved