t a resolution of 35 angstroms, the 3-D images identify critical components of these "transcriptional factor" or TF proteins, including TFIID, TFIIA and TFIIB. A model reconstructed from the images shows TFIID as a horseshoe-shaped structure surrounding a central cavity inside of which recognition and binding to dna takes place. TFIIA and TFIIB are shown to bind to the TFIID in a way that affects the size and shape of the cavity.

The production of proteins—or protein synthesis—begins when the electronic bonds that zip up dna’s double helix are undone and the two spiraling strands of bases are unwound. This leaves the genetic code contained on each strand of dna exposed and ready to be transcribed.