What is involved in going from genomic DNA to messenger RNA (mRNA)? The transciption process involves the concerted action of several proteins called transcription factors which process the DNA in a multi-step process into mRNA.
During transcription a single-stranded piece of RNA is made from a double-stranded piece of DNA. In eukaryotes a gene usually contains coding sequences or exons, interspersed with non-coding sequences or introns. After transcription, the non-coding sequences are removed to form message RNA (mRNA), which is then transferred to the cytoplasm for translation into proteins. A gene also contains specific sequences before and after the transcribed region that are involved in the regulation of transcription. Introns and exons along with these regulatory sequences make up the structure of a gene. The transcription process involves numerous proteins that act in a concerted fashion to allow RNA polymerase to work. These proteins are all subject to regulation and are points of control in the transcription of a gene.
Three different RNA polymerases (pol I, II, III) synthesize different types of RNA from a DNA template. Pol I, II, and III transcribe ribosomal RNA (rRNA), message RNA (mRNA), and transfer RNA (tRNA), respectively. The Pol II basal machinery binds to a region called the promoter, which is upstream of the DNA transcriptional start site. The promoter region is an important sequence as the strength of binding of the basal machinery to this region determines how frequently a gene will be transcribed. The frequency of gene transcription, as will be discussed further, is dependent on transcription factors and their control. The ...
In 750 to 1000 words describe the process of transcription in eukaryotes.