Question: 3. (Chapter 14) The lac operon of E coli controls the expression of genes that code for enzymes i…


3. (Chapter 14) The lac operon of E coli controls the expression of genes that code for enzymes involved in lactose metabolism. The operon system is inducible in that it can be turned on by the presence of lactose and then turned off when lactose is no longer present. Mutations to various regions of the lac operon have been discovered which affect both the control of gene expression and the function of the gene products. These mutations include: I produces a repressor protein that can not bind to the operator region I5 produces a repressor protein that can not be removed from the operator region oC -can not bind a repressor protein P-a promoter no longer recognized by RNA polymerase z produces a defective (non-functioning) ß-galactosidase enzyme Referring to the diagram of the lac operon in your text, detail the functionality of the lac operon (or partial diploid operon system) under the following genetic and cellular conditions. Repressed Constitutive yes no)(yes/no) Inducible GENES Lactose tYes/no) no no yes yes no yes IPO ГРОЗ yes Repressed: Means turned off currently whether or not it could be turned back on. Constitutive: Means on and can never be turned off. Inducible: Means the operon can still be turned on and off as cellular conditions change.

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3. (Chapter 14) The lac operon of E coli controls the expression of genes that code for enzymes involved in lactose metabolism. The operon system is inducible in that it can be turned on' by the presence of lactose and then "turned off" when lactose is no longer present. Mutations to various regions of the lac operon have been discovered which affect both the control of gene expression and the function of the gene products. These mutations include: I produces a repressor protein that can not bind to the operator region I5 produces a repressor protein that can not be removed from the operator region oC -can not bind a repressor protein P-a promoter no longer recognized by RNA polymerase z produces a defective (non-functioning) ß-galactosidase enzyme Referring to the diagram of the lac operon in your text, detail the functionality of the lac operon (or partial diploid operon system) under the following genetic and cellular conditions. Repressed Constitutive yes no)(yes/no) Inducible GENES Lactose tYes/no) no no yes yes no yes IPO ГРОЗ yes Repressed: Means turned off currently whether or not it could be turned back on. Constitutive: Means on and can never be turned off. Inducible: Means the operon can still be turned on and off as cellular conditions change.

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