The Transcription Process

Transcription is the process of converting stored DNA information into complementary mRNA with the help of the enzyme RNA polymerase.  Prokaryotes contain only 1 polymerase as compared to eukaryotic cells, which contain 3; RNA polymerase I, II, and III.  The polymerase II is found to be responsible for the transcription of all protein-coding genes6.  This is composed of 12 subunits, each interacting differently with the DNA and various other transcription factors (TFIIA, TFIIB…) creating the transcriptional complex.  Transcription goes through three distinct steps; initiation, elongation, and termination.  Initiation involves promoters and mediators that bind the complex to DNA and allow interaction of the transcriptional factors with the DNA to begin transcription5.  Elongation is the process in which a segment of the strand is unwound, exposing a single stranded DNA template.  During elongation, a phosphodiester bond will form between the correct ribonucleoside triphosphates forming a RNA chain.  Termination will then occur through downstream elements and various termination signals.  The pre-mRNA will undergo specific splicing and modifications of both ends before deemed mRNA.       

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Overview of the Transcription process

Comparison of Prokaryotic and Eukaryotic Transcription

Eukaryotic Transcription

Effects of Amanitin

Stem Cell Research

Artificial Transcription Factors

References

Above: Roger Kornberg

Below: RNA polymerase II-Source

Click to view transcription in Motion