T4 rII experimental system
... that the T4 rII experimental system enabled biologist Seymour Benzer to map a gene down to the level of one or two base pairs before the invention of DNA sequencing?
... that the <b id="mwDgo"><a href="./T4_rII_system" id="mwDgs" rel="mw:WikiLink" title="T4 rII system">T4 <i id="mwDgw">rII</i> experimental system</a></b> enabled <a href="./Biologist" id="mwDg0" rel="mw:WikiLink" title="Biologist">biologist</a> <a href="./Seymour_Benzer" id="mwDg4" rel="mw:WikiLink" title="Seymour Benzer">Seymour Benzer</a> to map a <a href="./Gene" id="mwDg8" rel="mw:WikiLink" title="Gene">gene</a> down to the level of one or two <a href="./Base_pair" id="mwDhA" rel="mw:WikiLink" title="Base pair">base pairs</a> before the invention of <a href="./DNA_sequencing" id="mwDhE" rel="mw:WikiLink" title="DNA sequencing">DNA sequencing</a>?