1. Compare and contrast class I and class II CRP-binding sites in promoters 11. True or False?

1.     Compare and contrast class I and class II CRP-binding sites in promoters

11. True or False? Auto regulation of r-protein expression is a result of the fact that an r-protein can bind to its own mRNA. Ans: True 12. True or False? The trp repressor protein regulates expression of both the trp structural genes and its own gene. Ans: True 13. True or False? The lac repressor has low affinity for nonspecific DNA; when not bound to the lac operator, it diffuses through the cytoplasm. Ans: False 14. True or False? After the removal of the inducer, lac mRNA levels rapidly decrease because the mRNA is unstable. Ans: True 15. True or False? Different mutations in the lacI gene can cause either constitutive expression of the lac structural genes, or their complete repression under all conditions.

15. Transcriptional control in which a repressor protein prevents a gene from being expressed is ___________ control. Ans: negative 16. Mutations in the lac operator generally result in _____________ expression of the lac structural genes. Ans: constitutive 17. Binding of the inducer to the lac repressor protein changes its structure so that it has lower affinity for the operator. This is an example of ____________ control. Ans: allosteric 18. A ____________________ regulatory circuit involves an inactive activator that is activated by an inducer.