Transcription is the process through which DNA is transcribed by an enzyme known as RNA Polymerase II (Pol II) into mRNA. The process of transcription proceeds in the 3’ to 5’ direction. There are three stages to the process of transcription initiation, elongation and termination. The process takes place in the nucleus of a cell. Transcription is started by the loose binding of Pol II to the DNA double helix. Pol II slides along the DNA helix in search of a core promoter sequence. The sequence contains binding sites for Pol II and other promoter elements that aid in the binding and initiation of transcription. Once the promoter has been found Pol II binds tightly to the DNA strand. Pol II then melts about 17 bp of the DNA being transcribed (stryer). This localized melting of the DNA creates a template (sense) and a non- template (anti-sense) strand. The template strand will be used for base pairing with the newly forming mRNA. Elongation of the new RNA strand can now begin. Elongation begins with the formation of the first phosphodiester bond (stryer). A transcription bubble is formed upon melting of the DNA and binding of ribonucleoside triphosphate. Inside the transcription bubble RNA-DNA hybrids about 8 bps long forms. Elongation of the mRNA strand proceeds at about 170 angstrom per second in the transcription bubble (stryer). The RNA-DNA hybrid rotates inside the transcription bubble to allow the 3’-OH end of the mRNA in the active site.as the hybrid is about to exit Pol II the hybrid is forced to separate before exiting Pol II. The DNA rewinds with its compliment and the RNA exits as a single strand. The DNA strand is unwound and rewound at about the same rate during transcription. Termination is the last step in the transcription process. Termination is brought about when Pol II encounters a stop codon. After the stop codon has been transcribed Pol II pauses for a moment. This pause allows either rho to catch the transcription complex and causes a dissociation of the RNA from the Pol II or a series of weak bonds is broken and the RNA is released and Pol II releases the DNA which has reformed its double helix motif. Thr newly formed RNA is then modified to excise introns and a cap and tail are added to the mRNA to prevent degradation during export to the cytoplasm.