Much of the class discussions have been about/on the structures and operations that occur within the eukaryotes. Today, however, we began a discussion on the gene regulation, whether to transcribe for a protein (gene) or not, of prokaryotic organisms. Unlike eukayotes, prokaryotes have operons. Operons are multiple structural genes that are regulated by a common operator and promoters. This helps prokaryotes to be more efficient since their surface ares is not as large as eukaryotes.
We humans do possess the E.Coli bacteria but it is only present in our intestinal tract. Furthermore, the prokaryote organism E.Coli, like most bacterias, posses a repressed gene know as the lac operon. The lac operon gene is repressed because it is not constantly used but it may be needed with is why the gene has not been completely eliminated. In the presence of glucose, the lac operon is repressed because the sugar of choice are those sugars that are common to animal like glucose.
If for whatever reason glucose is not readily available and the lactose sugar is present it then binds to the repressor molecule and it released from the regulartory site on the lac operon. It is released because the shape of the repressor molecule will change its shape and no longer will be able to bind properly at the operator site. The one RNA polymerase that bacteria have can then bind at the operator site and begin its transcription of mRNA of the lac operon. This mRNA then is then joined by ribosomes and the proteins are made that E.Coli needs in order to break down the lactose into a usable sugar needed for it metabolic functions.