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L32: Reg Gene Expr
USCSOM: Biochemistry: L32 Regulation of Gene Expression
Question | Answer |
---|---|
Describe lactose. | galactose linked Beta-1-4 glucose |
What two ways does lactose enter E. coli? | lactose permease and hydrolytic enzyme that splits lactose into galactose and glucose |
What does coordinate regulation mean? | The activity of both genes are coupled to each other |
Explain catabolite repression in the lac E. coli pathway | activity of lactose enzyme is decreased when glucose is also added |
What is the order of the polycistronic messenger for lactose metabolism in E. coli? | Promoter - lacZ - lacY |
What does lacZ gene promote? | Beta-galactosidase |
What does the lacY gene promote? | lactose permease |
What is an operon? | a set of genes that are under control of a single operator |
What happens when an inducer binds to a repressor? | repressor loses its affinity and opens up promotor for RNA polymerase |
What is CRP/CAP? | cAMP regulator protein/ cAMP activator protein; binds upstream of promotor |
What two things are necessary to get good expression of the lac operon? | inducer present; CRP bound |
What increases CRP's affinity to bind to DNA? | cAMP |
How to cAMP levels vary with respect to the growth rate in E. coli? | inverse |
Catabolic pathways are controlled by induction or repression? | induction by substrate |
Anabolic pathways are controlled by induction or repression? | repression by products |
What happens to activity in the lac operon in AAs only? | |
What happens to activity in the lac operon in AA plus lactose? | |
What happens to activity in the lac operon in AA, plus lactose, plus glucose? | |
What happens to activity in the lac operon when mutation inactivates the repressor? | |
What happens to activity in the lac operon when mutation allows repressor to bind to DNA but lose affinity for allolactose? | |
What happens to activity in the lac operon when mutation lies in the operator such that the repressor no longer binds to it? | |
What happens to activity in the lac operon when mutation inactivates the CRP protein? | |
What happens to activity in the lac operon when mutation interferes with synthesis of cAMP |