"No, no. That’s good. It’s inaccurate, but you’re on the right track. We
think of DNA as a code. A code with four letters. The letters are based on the 
four nitrogenous bases that are in the DNA: A for adenine, G for guanine, C for 
cytosine, and T for thymine. The four letters are arranged in different 
combinations and different lengths to make up a gene. There might be tens of 
thousands, or hundreds of thousands, or even millions of these letters defining 
a single gene. It goes like this: GCATGTATCCTGTA and so on."