The lactose (lac) operon in E. coli is an example of a gene that is repressed when lactose is not available in a cell. In 3-5 sentences, explain what this means, using correct terminology. (4 points)
The lactose operon in E. coli refers to a cluster of genes involved in lactose metabolism. When lactose is not present in a cell, a repressor protein called LacI binds to a specific region on the DNA called the operator site. This blocks the promoter site, preventing RNA polymerase from initiating transcription of the genes involved in lactose metabolism. Therefore, the lac operon is repressed (switched off) in the absence of lactose, ensuring that the cell conserves energy by not producing unnecessary lactose-metabolizing proteins.
The lactose (lac) operon in E. coli is a cluster of genes involved in lactose metabolism. When lactose is not available in the cell, the lac operon is repressed, meaning that the transcription of the genes in the operon is inhibited. This repression is mainly controlled by a regulatory protein called the lac repressor. In the absence of lactose, the lac repressor binds to the operator region of the operon, preventing RNA polymerase from binding to the promoter and initiating transcription. Therefore, without lactose, the genes involved in lactose metabolism are not expressed.
The lactose (lac) operon in E. coli is a cluster of genes that are involved in the metabolism of lactose. When lactose is not available in a cell, the genes of the lac operon are repressed, meaning that their expression is inhibited. The repression occurs through the interaction of a repressor protein with the operator region of the operon's promoter. In the absence of lactose, the repressor protein binds to the operator, preventing RNA polymerase from binding to the promoter and initiating transcription. This repression mechanism helps conserve energy by preventing the synthesis of enzymes required for lactose metabolism when lactose is not present.
