National Geographic

The Code of Life: My New Feature for Nautilus Magazine

One of the strangest episodes in the history of biology occurred in 1953. A physicist named George Gamow, who is best known for his work on the Big Bang, sat down and read a new paper by two biologists named James Watson and Francis Crick. They reported that DNA is arranged as a double helix. Gamow then wondered how DNA encodes proteins. DNA used four “letters” in its genes, while proteins are built from a chemical alphabet of twenty amino acids. He realized that the question turned life into a problem in cryptography. Gamow came up with an explanation for life’s code that turned out to be wildly wrong. But it prompted other researchers to crack the code.

In the new issue of Nautilus (a new magazine about science and philosophy), I’ve written a feature about the history and future of the genetic code. There’s still a lot we don’t understand very well about the genetic code–for example, why all living things use the same one. But at the same time, scientists are learning how to alter the code, to generate forms of life fundamentally different from anything that came before. Check it out.

There are 2 Comments. Add Yours.

  1. Marcoli
    October 28, 2013

    Very interesting. There is a strong case that natural selection has driven evolution of the genetic code so that it tolerates many mutations and errors in protein translation. The correspondence between codons and the amino acids they specify is not random, which is what would more likely occur if it was entirely established in a ‘frozen accident’. First, the code shows a tendency to specify chemically similar amino acids with similar codons. This is especially true for the hydrophobic amino acids. There is therefore an increased chance that a mutation or translation error that substitutes an amino acid will use a chemically similar amino acid, and this may allow the protein to still work. Second, there is a strong correlation between how frequently amino acids are used and how many codons specify that amino acid. For example, methionine is not used very often and it uses only one codon. Serine and Leucine are among the most frequently used amino acids, and they have each commandeered six codons. There are other features of the code that imply it was evolved from a simpler code that used fewer tRNA molecules and fewer amino acids. Maybe it also has features of a frozen accident, but the characteristics described above do not seem random.

  2. pam spermia
    October 31, 2013

    “nature is in fact, across all scales and all levels of phenomena, a unity. It’s not a coincidence that electrons spinning around an atomic nucleus and planets going around a star, and star clusters orbiting around the gravitational centre of a galaxy … it’s no coincidence that these systems exhibit the same kind of order on different scales. And yet science would say that is a coincidence. You know, P.W.Bridgeman, who was a philosopher of science, defined a coincidence as what you have left over when you apply a bad theory! It means, you know, that you’ve overlooked something, and what jumps out at you as a coincidence is actually a set of relationships whose casuistry — whose relationships to each other, are simply hidden from you.”
    life is astonshing and I foresee an age in the not so distant future of more and more of our worlds population are becoming interested in discovering what things our universe has in storage for us.

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