Now that the human genome has been sequenced it is time to return to simpler questions, like what is a gene?

• In the early 1900s, a gene was as an abstract concept to explain the hereditary basis of traits. 
  
• In the 1930s, Beadle introduced the concept of "one gene, one enzyme," which later became "one gene, one polypeptide."
  
• Today, a gene is defined in molecular terms as "a complete chromosomal segment responsible for making a functional product."  For more detail, see this week's Science.

Sequencing the genome is just the first step in a much larger project Human Biology Project.  As Eric Lander of the Whitehead Institute reminds us, "starting today, the real serious analysis of things can begin."

Powered by faster gene chips the cost of genetic analysis continues to plummet. At the beginning of the project "it cost $10 to definitively identify a single base pair... and a highly trained technician could scan perhaps 10,000 base pairs in a day. Now the equivalent cost is 5 cents and lightning-fast robotic sequencers routinely process 10,000 base pairs a second."   Now that's progress.  Next step, sequencing the proteome.