The Transcription of Prokaryotic Cells and Eukaryota Cells

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The formation of RNA from DNA is termed as transcription. This process is very essential because it is this RNA which then codes for amino acids and hence proteins. The process of transcription is accomplished by an enzyme known as RNA polymerase. The strand of the DNA that is transcribed is in the 3’ to 5’ direction. Hence the transcript that is formed in the opposite direction that is 5’ to 3’ direction. This is because the RNA polymerase functions in the 3’ to 5’ direction on the DNA creating a complementary strand on RNA in which the Adenine always pairs with Uracil whereas the guanine always pairs with the cytosine. Prokaryotic cells contain only one type of RNA polymerase. This RNA polymerase only is responsible for the formation of all the different types of RNA in the prokaryotes which includes the mRNA, rRNA, and tRNA. RNA polymerase has a distinguishing quality that it can initiate the process of transcription by itself. There are particular sequences on the DNA strand where this enzyme binds to carry out the process of transcription. Promoters and enhancers are these sequences which are located on the DNA strand. Promoters are near to the point where transcription starts whereas enhances are many nucleotides away and their primary role is to alter the number of times transcription takes place. The structure of the enzyme RNA polymerase in prokaryotes can be understood by considering an organism of this kingdom which is known as E. coli. In E. coli the RNA polymerase has 2 alpha subunits, one beta subunit, one beta prime subunit, and a sigma factor. It is this sigma factor which helps in the binding of the RNA polymerase to the DNA strand. The region to the left of the start point of transcription is known as 5’ flanking region.