ANTA01H3 Chapter 4: Chapter 4 Notes
Document Summary
The entire human genome has been sequenced as of spring 2003. We still need to discover how the dna builds an organism. Most of the genome is not composed of genes, possibly 98% of doesn"t code for proteins. Used to be referred to as junk dna . Some of it marks the beginnings and ends of coding sequences. Some serves to regulate gene function and activity level. Some jumps around carrying other dna with it, allowing the genetic code to reshuffle its elements. This provides a partial explanation for why a small number of genes can produce such a huge variety of proteins. Some noncoding dna is made up of repetitive sequences that may do nothing. Some of our dna may be very ancient, and some may have been transferred from microbes. The coding sequences are not lined up neatly together but are scattered and interrupted by noncoding sequences.