What is an operon? In what type of organism would you expect to find an operon? Give an example...


What is an operon? In what type of organism would you expect to find an operon? Give an example of an inducible operon, describe the overall function of the gene(s) it encodes, and how it is regulated. How is an operon typically organized? Describe a type of mutation in any region of the operon that could, potentially, result in lost ability to induce the operon.

Gene Expression Regulation

Gene expression mainly includes two major steps, namely transcription, and translation. The regulation of gene expression includes factors that regulate these two steps so that there is firm regulation of protein synthesis which helps in the maintenance of proper cellular homeostasis.

Answer and Explanation: 1

The operon is the aggregation of structurally related genes that are under the control of the same promoter/operator so that their expression can be regulated by specific protein molecules upon signal transduction.

The operon is mainly found in prokaryotes because in prokaryotes the mRNA is polycistronic. In the eukaryotes operon system is not present because the mRNA is monocistronic in nature.

Example of an inducible operon is Lac Operon. In Lac operon, the genes required for lactose (disaccharide) metabolism like Beta-galactosidase, etc are under the control of the same promoter, operator. When monosaccharide is present in abundance in the media enzymes responsible for the metabolism of disaccharide are not needed. Then the lac operon is not activated and the repressor binds at the operator which inhibits the transcription of structural genes by RNA polymerase. But when monosaccharide is depleted in the media, then disaccharide is only available. In this condition, lactose gets converted into allolactose which binds with the repressor and inhibits the repressor binding with the operator. This along with Catabolite Activator protein activates the transcription of structural genes and result in the metabolism of disaccharide. So in presence of disaccharides lactose, the lac operon gets induced.

In an operon first, there is a promoter, then operator, followed by structural genes.

In the lac operon, if there is a mutation in the repressor so that it cannot bind with allolactose. Then in presence of lactose also the operon will be not induced.

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Operon: Definition & Sequencing


Chapter 18 / Lesson 17

Understand what an operon is. Define an operon, understand its function, and explore the sequence of a bacterial operon. Discover some examples of an operon.

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