| 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? |
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| What happens to activity in the lac operon in AA plus lactose? |
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| What happens to activity in the lac operon in AA, plus lactose, plus glucose? |
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| What happens to activity in the lac operon when mutation inactivates the repressor? |
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| What happens to activity in the lac operon when mutation allows repressor to bind to DNA but lose affinity for allolactose? |
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| What happens to activity in the lac operon when mutation lies in the operator such that the repressor no longer binds to it? |
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| What happens to activity in the lac operon when mutation inactivates the CRP protein? |
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| What happens to activity in the lac operon when mutation interferes with synthesis of cAMP |
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