virus known as the "phage" is perhaps the worlds
most simple biological entity capable of directing its own duplication.
The phage is little more than a strand of DNA contained within a
protein coat. This simplicity was attractive to early researchers
trying to determine whether the molecules of inheritance were proteins
or DNA. In a famous "blender" experiment at Cold Spring
Harbor Laboratory, Alfred Hershey and Margaret Chase allowed phages
tagged with radioactive ions to infect a cell, and confirmed that
DNA was indeed the hereditary molecule. For more details, see a
diagram of the famous blender experiment on the Access Excellence
the phage bacterial virus as one of the original model organisms
"The phage was discovered around 1915 and [it was
thought] that maybe because they multiply and kill bacteria they
would be effective antibiotics. So they were studied largely initially
to cure disease, but that didnt seem to work out, and twenty
years later a few scientists said, Well maybe since they contain
DNA they would be good model systems for studying the gene.'
was that you could do experiments overnight; if you were breeding
corn, you could only have one cross per year. If you went down to
Florida, maybe youd have two crosses per year. With phages
you can get a cross every day."
Watson, Co-discoverer of the DNA double helix and president
of Cold Spring Harbor Laboratory
viruses and the way genes are organized:
"They dont have very much DNA at all, they
sometimes will code three different proteins with the same DNA by
just shifting how theyre doing it. Theres nothing simple
and elegant and neat about the way genes are laid out. Life uses
every trick in the book to get a little bit of an advantage. Not
tidy, but very effective."
Lander, Director, Whitehead Institute's Center for Genome Research