Summary

This chapter summarizes several facts about the human genome in a bullet-point format as follows. There are over 3 billion letters of DNA which all consist of just four letters. It is divided into 23 pairs of chromosomes and encodes over 20,000 genes. It is inventive, dynamic, and beautiful. Ninety-eight percent of the genome is dedicated to something other than genes. It is "encrusted with history," has repeated elements, and enormous "gene families" (323-324). It contains inactivated genes and accommodates both variation and similarity. The first gene encodes the sense of smell and the last gene encodes the immune system. The ends of chromosomes have "telomeres" which prevent them from fraying and degenerating (325). Though we understand the genetic code, we know very little about the genomic code. It imprints on itself in response to alterations in the environment. It...