Recently Roger D. Kornberg was given the Nobel Prize for uncovering the cellular apparatus responsible for reading the blueprint of life in Eukaryotic cells.  Kornberg and colleagues discovered that not only is RNA polymerase required for reading the blueprint of life, but the most interesting thing may be RNA polymerases’ function at the right place and time.  Furthermore, Kornberg did most of his research on yeast transcription, which happened to be almost exactly the same as how transcription occurs in humans.  This is quite fascinating considering humans are very complex compared to a simple yeast cell, yet we share the same way of expressing our genes.  Although the basic process of transcription described below has been known for some time, Kornberg has now deciphered how it may occur at the atomic level and this detail is discussed in my detailed transcription page.

            There are three basic steps of transcription: initiation, elongation, and termination.  Transcription begins with the binding of RNA polymerase to the promoter on the DNA.  This is facilitated by 5 general transcription factors and mediator, but I will not go into these yet.  By binding to the promoter region the RNA polymerase is now in its proper orientation to begin transcription.  Binding of RNA polymerase causes the double-stranded DNA to unwind creating a transcription bubble.  With the initiation complex now ready to go, the RNA polymerase can move into the elongation phase of transcription by separating from the general transcription factors and mediator allowing RNA polymerase promoter clearance.  To obtain promoter clearance, nucleotide triphosphates must be added until the RNA-DNA hybrid complexed with RNA polymerase can be self sustaining.  After promoter clearance elongation continues by the addition of nucleotides to their correct base-pair on the template DNA that is being unwound and rewound as polymerase moves along.  The nucleotides are then linked together on the growing RNA strand by phosphodiester bonds.  The elongation process continues along the DNA strand moving extremely fast and accurately until the polymerase reaches a terminator region on the DNA which signals that the gene has been transcribed.  RNA polymerase will then dissociate from the DNA strand causing the DNA to become double stranded again and also releasing the newly created messenger RNA which is free to be processed and translated by the cell to make the protein that the gene was coding for.