Inducible Operon vs Repressible Operon

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Inducible Operon vs Repressible Operon Genetic regulation is a process where certain proteins and other kinds of stimuli tend to cause a cell to express genes or not express them. The bacteria cell system is small system, but it carries out a lot of activities and must do so economically and efficiently, therefore actions of these genes must be regulated. There are two types of regulatory systems: inducible and repressible An operon is a cluster of genes that work together to form a polycistronic mRNA. It consists of structural genes, a promoter region, an operator region, and a regulatory gene. Structural genes code for the enzymes themselves. RNA polymerase transcribes all of the genes into a polycistronic mRNA. The promoter is the site where the RNA polymerase binds to the DNA prior to beginning transcription. The operator serves as the binding site for the protein called the repressor. The regulatory gene encodes the repressor protein. An inducible operon is an operon in which the presence of a key metabolic substance induces transcription of the structural genes. One example of an inducible operon is lac operon and the inducer of this operon is lactose. A repressible operon is an operon which always transcribes structural genes unless a repressor is present. One example of a repressible operon is trp operon and the co-repressor of this operon is tryptophan. Both lac operon and trp operon have similarities and differences Similarities 1. Both lac operon and trp operon have structural genes with related function are controlled by a single promoter/operator. 2. Both lac operon and trp operon have negative control regulation system controlled by repressor. There is a regulatory gene in the operon which encodes the repressor protein that attach to the operator to prevent transcription. Differences 1. In term of structure, the lac operon has three structural genes: lacZ, lacY, and lacA. Whereas the trp operon has five structural genes: trpE, trpD, trpC trpB and trpA. 2. In term of function, an inducible operon is generally involves in

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