Gene Cycle

Essay by EssaySwap ContributorHigh School, 10th grade February 2008

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A gene goes through two processes while it is inside the nucleus of a eukaryotic cell. It goes through transcription then RNA processing. Both of these processes are have many steps within them.

First, a gene goes through transcription. Transcription is three steps long, initiation, then elongation, and termination. The initiation stage is when the RNA polymerase binds to the gene at the promoter region of it. The polymerase moves down the gene, which is a DNA double helix, and unwinds it, exposing the coding strand of it. In the elongation period in the coding sequence region, the RNA polymerase makes an mRNA strand that is supplementary to the DNA coding strand. As it moves down the helix, it lets the mRNA trail off behind it not attached to the gene. When the RNA polymerase reaches the terminator region, it receives a signal to release from the gene and let the new mRNA strand go.

So the end result is a new mRNA strand supplementary to the gene's coding strand.

RNA processing is a process in which modifications happen to the gene. A strand of mRNA is made up of 2 things, exons and introns. The first step is called intron splicing, as in the introns are cut out of the mRNA. The next step is when a methyl cap (MGcap) is added to the beginning of the mRNA strand. The last step is when a Poly-A tail is added to the end of the mRNA strand. The tail is made of up multiple adenines linked together. There are three theories as to why RNA processing occurs, the first is that it signals the mRNA and tells it its time to leave the nucleus. The second is that the MGcap and the Poly-A tail protect the mRNA strand...