{"id":347,"date":"2023-04-14T01:00:48","date_gmt":"2023-04-14T01:00:48","guid":{"rendered":"https:\/\/sites.wp.odu.edu\/thetienvo\/?p=347"},"modified":"2023-04-14T01:02:33","modified_gmt":"2023-04-14T01:02:33","slug":"lac-operon-assignment","status":"publish","type":"post","link":"https:\/\/sites.wp.odu.edu\/thetienvo\/2023\/04\/14\/lac-operon-assignment\/","title":{"rendered":"Lac Operon Assignment"},"content":{"rendered":"\n

Lac Operon Assignment\u00a0<\/strong><\/p>\n\n\n\n

Draw and describe the regulation of the Escherichia coli lac operon in the following situations:<\/p>\n\n\n\n


1. In the absence of lactose (disregard presence or absence of glucose).<\/strong><\/p>\n\n\n

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There is a repression of the structural genes when there is no lactose in the cell. With no lactose in the cell, there is no inducer. In the absence of lactose, the repressor protein is going to be made and is going to be able to bind to the operator. Once it binds to the operator, it is going to be impossible for the RNA polymerase to bind to the promoter and move down to the operator and transcribe the structural genes. Thus, with the absence of lactose, transcription cannot occur.<\/p>\n\n\n\n

2. In the presence of lactose (disregard presence or absence of glucose).<\/strong><\/p>\n\n\n

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In the presence of lactose, induction occurs. The inducer, lactose, binds to the repressor protein and that is going to change the shape of the repressor protein. Once the repressor changes it shape, it will no longer be able to bind to the operator. When the repressor protein cannot bind to the operator, the RNA polymerase will bind to both the promoter and operator which will allow it to go through and transcribe the structural genes, and thus, allowing those genes to be further translated.<\/p>\n\n\n\n


3. In the absence of glucose (disregard the presence or absence of lactose<\/strong>).<\/p>\n\n\n

\n
\"\"<\/a><\/figure><\/div>\n\n\n

In the absence of glucose, the cAMP-CRP complex binds to the promoter. If glucose is not present, then there is going to be a higher amount of adenyl cyclase. Having more adenyl cyclase will cause it to be involved in the conversion of ATP to cAMP. The cAMP will then combine with CRP monomers which will then bind to the promoter. This combination will then encourage the RNA polymerase to bind to the promoter, allowing it to go through and transcribe the structural genes.<\/p>\n\n\n\n


4. In the absence of glucose AND the presence of lactose.<\/strong><\/p>\n\n\n

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In the absence of glucose and the presence of lactose, the cAMP-CRP complex will bind to the promoter due to glucose not being present and the repressor will be released by the inducer because lactose is present. Having lactose also means that there is an inducer present. Since there is an inducer, it is not possible for the repressor protein to be active. Having the inducer bound to the repressor protein does not inhibit the expression of the structural genes. However, having high-level expression activates positive regulation with CRP and cAMP combined. Therefore, the cAMP-CRP complex will bind to the promoter allowing the RNA polymerase to bind to the promoter as well. Once the RNA polymerase binds to the promoter, it will be able to go through and transcribe the structural genes.<\/p>\n\n\n\n


Finally, describe where in the process of gene expression (transcription, post-transcription, translation, post-translation) this regulation takes place.<\/strong><\/p>\n\n\n\n

The regulation of the Escherichia coli lac operon takes place in the transcription portion of gene expression. Positive regulators, such as the CRP-cAMP complex, allow there to be physical contact with RNA polymerase and the promoter, which enhances the ability to initiate transcription. With lactose present, the inducer can bind to the repressor protein and change its shape. RNA polymerase will then bind to both the promoter and operator, allowing it to transcribe the structural genes.<\/p>\n","protected":false},"excerpt":{"rendered":"

Lac Operon Assignment\u00a0 Draw and describe the regulation of the Escherichia coli lac operon in the following situations: 1. In the absence of lactose (disregard presence or absence of glucose). There is a repression of the structural genes when there is no lactose in the cell. With no lactose in the cell, there is no… <\/p>\n

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