The promoter is the site on DNA where RNA polymerase binds in order to initiate transcription. coli has three genes that encode for enzymes that enable it to split and metabolize lactose (a sugar in milk). Example of Inducible Transcription: The bacterium E.There is also a regulator gene, which codes for the synthesis of a repressor molecule hat binds to the operator The operator gene is the sequence of non-transcribable DNA that is the repressor binding site. The regulator gene codes for synthesis of a repressor molecule that binds to the operator and blocks RNA polymerase from transcribing the structural genes.The operator gene is also non-coding it is just a DNA sequence that is the binding site for the repressor.The promoter gene doesn't encode anything it is simply a DNA sequence that is initial binding site for RNA polymerase.Regulation of protein production is largely achieved by modulating access of RNA polymerase to the structural gene being transcribed. The structural genes contain the code for the proteins products that are to be produced.These researchers proposed that production of the enzyme is controlled by an "operon," which consists a series of related genes on the chromosome consisting of an operator, a promoter, a regulator gene, and structural genes. occurs through regulation of transcription, which can be either induced or repressed. In 1965 Francois Jacob, Jacques Monod, and Andre Lwoff shared the Nobel prize in medicine for their work supporting the idea that control of enzyme levels in cells is regulated by transcription of DNA. Gene expression is primarily controlled at the level of transcription, largely as a result of binding of proteins to specific sites on DNA. By gene expression we mean the transcription of a gene into mRNA and its subsequent translation into protein.
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