ch18 bio

ch18 bio - Anna Lee Period 5 1/5/2010 CONCEPT CHECK Chapter...

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Anna Lee Period 5 1/5/2010 CONCEPT CHECK Chapter 18 18.1 1. The lac inducer stops the lac repressor making the lac operon. This makes the transcription of the lac operon. The trp corepressoer turns on the trp repressor and unlike the lac the trp corepressor turns off the trp peron. 2. If the active repressor cannot bind to the lac operator the B-galactosidase would never stop being made. Even if lactose isn’t there it would make the enzyme so the cell would run out of material 3. When lactose is scarce, the RNA polymerase, repressors, and activators to the lac operon the repressor would not go away from the operator. This makes the RNA polymerase not bind to the promoter. But when glucose is scarce, the cAMP and the CAP would bind to the promoter. The RNA polymerase now is ok to work because of the cAMP and the CAP. If sugar were present, the transcription of other genes outside the lac operon would be regulated regularly and the transcription of these genes would be allowed. 18.2 1. Histone acetylation and DNA methylation has opposite effects on gene expression. DNA methylation is the opposite of histone acetylation because acetylation helps the
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ch18 bio - Anna Lee Period 5 1/5/2010 CONCEPT CHECK Chapter...

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