" The DNA molecule is shaped like a twisted ladder, and the rungs of the ladder—the nucleotides—can hold vast amounts of information, the code of life. A gene is a short stretch of DNA, typically about a thousand letters long, that holds the recipe for a protein or a group of related proteins. The total assemblage of an organism’s genetic code—its full complement of DNA, comprising all its genes—is the organism’s genome. "

― Richard Preston , The Demon in the Freezer