Genes are accessed and read by the cell in small segments at a time, similar to how information is read from a cassette tape.

“For the children at home, a cassette tape is a plastic cassette, with a reel, on either side, of magnetic tape. But the important thing here for this analogy, is that if you turn it on its side, that tape includes a lot of information, but only a little bit is readable at any given time.”