<p><font color="#000000">The <strong>phi X 174</strong> (or <strong>phi X</strong>) bacteriophage was the first organism to have its DNA-based <font color="#810081">genome</font> sequenced, by Fred Sanger and his team in 1977.<sup class="reference" id="cite_ref-0">[1]</sup> In 1962, Walter Fiers had already demonstrated the physical, covalently closed circularity of phi X 174 DNA.<sup class="reference" id="cite_ref-1">[2]</sup></font></p><p><font color="#000000">This phage has a very small amount of DNA. It has 11 genes in 5386 bases (it is single stranded) in a circular topology. Several of them expressing similar function in two groups. The GC-content is 44% and 95% of nucleotides are coding genes.</font></p>

<li id="cite_note-0"><strong>^</strong> Sanger F, Air GM, Barrell BG, Brown NL, Coulson AR, Fiddes CA, Hutchison CA, Slocombe PM, Smith M., &quot;Nucleotide sequence of bacteriophage phi X174 DNA&quot;, <em>Nature</em>. <strong>1977 </strong> Feb 24;265(5596):687-95 </li> <li id="cite_note-1"><strong>^</strong> Fiers, W., and R. L. Sinsheimer, &quot;The structure of the DNA of bacteriophage PhiX 174. III. Ultracentrifuge evidence for a ring structure&quot;, <em>J. Mol. Biol.</em> <strong>5:</strong>424-434, <strong>1962 </strong> </li> <li id="cite_note-2"><strong>^</strong> <cite style="FONT-STYLE: normal">Smith, Hamilton O.; Clyde A. Hutchison, Cynthia Pfannkoch, J. Craig Venter (2003-12-23). &quot;Generating a synthetic genome by whole genome assembly: {phi}X174 bacteriophage from synthetic oligonucleotides&quot;. <em>Proceedings of the National Academy of Sciences</em> <strong>100</strong> (26): 15440-15445. doi:<span class="neverexpand">10.1073/pnas.2237126100</span><span class="reference-accessdate">. Retrieved on <strong>2007</strong>-10-08.</span></cite><span class="reference-accessdate"><span class="Z3988" title="ctx_ver=Z39.88-2004&amp;rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&amp;rft.genre=article&amp;rft.atitle=Generating+a+synthetic+genome+by+whole+genome+assembly%3A+%7Bphi%7DX174+bacteriophage+from+synthetic+oligonucleotides&amp;rft.jtitle=Proceedings+of+the+National+Academy+of+Sciences&amp;rft.date=2003-12-23&amp;rft.volume=100&amp;rft.issue=26&amp;rft.aulast=Smith&amp;rft.aufirst=Hamilton+O.&amp;rft.pages=15440-15445&amp;rft_id=info:doi/10.1073%2Fpnas.2237126100&amp;rft_id=http%3A%2F%2Fwww.pnas.org%2Fcgi%2Fcontent%2Fabstract%2F100%2F26%2F15440"><span style="DISPLAY: none">&nbsp;</span></span></span> </li>