Sedeer el-Showk The Language of DNA February 01, 2016
Four letters make up the genetic alphabet: A, T, G, and C. In one sense, a gene is nothing more than a sequence of those letters, like TTGAAGCATA…, which has a certain biological meaning or function. But what makes a series of letters have meaning, what gives it a function? In the most straightforward case, it happens because a gene is translated into a protein, a tiny molecular machine. Proteins are made of amino acids, and each gene lists the amino acids that make up a specific protein. Since there are only four genetic letters but 20 different amino acids, the information in a gene is organized into three-letter words called codons; there are only 16 ways of combining four letters into two-letter words, but bumping up the length by a single letter creates 64 possible three-letter words — more than enough to have one for each amino acid. The molecular machinery of the cell assembles a protein by reading through the appropriate gene on a strand of DNA, and stringing together the amino acids that match the codons.
What is the DNA code?
The DNA code is really the “language of life.” It contains the instructions for making a living thing. The DNA code is made up of a simple alphabet consisting of only four “letters” and 64 three-letter “words” called codons. It may be hard to believe that most of the wonderful diversity of life is based on a “language” simpler than English—but it’s true.
This code isn’t literally made up of letters and words. Instead, the four letters represent four individual molecules called nucleotides: thymine (T), adenine (A), cytosine (C), and guanine (G). The order or sequence of these bases creates a unique genetic code.
These codon “words” in the genetic code are each three nucleotides long—and there are 64 of them. If you do the math, this is as many three-letter combinations words as you can get with just four letters. ATG and CCC are a couple of examples of codons.