Imagine that the genome is a book. There are twenty-three chapters, called CHROMOSOMES. Each chapter contains several thousand stories, called GENES. Each story is made up of paragraphs, called EXONS, which are interrupted by advertisements called INTRONS. Each paragraph is made up of words, called CODONS. Each word is written in letters called BASES. (Location 138)
genomes are written entirely in three-letter words, using only four letters: A, C, G and T (which stand for adenine, cytosine, guanine and thymine). And instead of being written on fiat pages, they are written on long chains of sugar and phosphate called DNA molecules to which the bases are attached as side rungs. Each chromosome is one pair of (very) long DNA molecules. (Location 157)
Life is a slippery thing to define, but it consists of two very different skills: the ability to replicate, and the ability to create order. (Location 214)