. >> i'm terry gaasterland, and i'm a professor of computational biology at university of california-san diego. i am in the marine biology department, and i have collaborators in new york and i have collaborators here in oregon. you can think of dna in many different ways. if you're a computer scientist, you can think of it as ones and zeroes or you can think of it as four letters: a, c, g, and t. if you're a biologist, you think of dna as a long, complex molecule that is made of each of the compounds that a, c, g, and t represent. a genome is the specific bundle of dna that's in a particular cell. so we can think of dna as being paragraphs, words, sentences, where a genome would be the specific book that is you. dna sequencing is the process of trying to read the letters that are in the book. so sequencing is the process of fragmenting that dna into little tiny pieces and reading a little bit of each of the fragments. and now you've got all these 500-, 700-letter words and you need to fit them all back together. early on, when people started trying to sequence genomes, people came up with the