Prokaryotic Transcriptional Regulation

Question 1

As bacteria enables a metabolic shift to lactose, ___________ and ______ __________ increase

Answer 1

beta galactosidase, lactose permease proteins

Question 2

What is the function of beta galactosidase

Answer 2

cleaves lactose into glucose and galactose

Question 3

What is an operon?

Answer 3

A cluster of related genes with similar functions found in prokaryotes, controlled by an operator

Question 4

What does an operon consist of?

Answer 4

-Promoter
-Operator
-Coordinated gene cluster

Question 5

A/an _______ is a sequence near the start of the operon that can _____ or ________ transcription depending on whether it is bound to an inhibitor

Answer 5

Operator, allow, inhibit

Question 6

The lac operon regulates _______ and __________ expression in e. coli

Answer 6

Beta galactosidase, lactose permease

Question 7

The _______ binds the RNA polymerase complex in an operon

Answer 7

promoter

Question 8

What is lacO

Answer 8

operator

Question 9

What is lacY

Answer 9

lactose permease

Question 10

What is lacZ

Answer 10

beta galactosidase

Question 11

What is lacI

Answer 11

repressor protein

Question 12

___________ regulated transcription involves a repressor protein that inhibits transcription, required genes are turned off

Answer 12

Negatively

Question 13

The _____ gene is __________ expressed at low levels

Answer 13

lacI, constitutively

Question 14

Are beta galactosidase and lactose permease produced when glucose is present? Why or why not?

Answer 14

No, a repressor binds the operator

Question 15

How does the repressor protein for the lac operon work?

Answer 15

-Tetrametric protein made of 4 subunits
-Binds tightly to the operator and twists DNA into a loop
-Prevents RNA polymerase from binding when glucose is in use

Question 16

How is negative regulation allosterically inhibited when the cell switches to metabolizing lactose?

Answer 16

-Lactose binds to the repressor protein
-Lactose acts as an inducer molecule and changes the protein conformation

Question 17

_________ regulation of the lac operon promotes production of ____________ and ____________

Answer 17

Positive, beta galactosidase and lactose permease

Question 18

A decrease in glucose causes an increase in intracellular _______ levels, which contributes to _______ regulation

Answer 18

cAMP (cyclic adenosine monophosphate), positive

Question 19

When is adenyl cyclase inhibited? What does this do?

Answer 19

When glucose levels are high

Prevents the enzyme from catalyzing cAMP from ATP, resulting in low cAMP levels

Question 20

What is the cAMP receptor protein?

Answer 20

-Involved in positive regulation
-When bound by cAMP will bind to the CAP-cAMP binding site

Question 21

What is positive transcriptional regulation?

Answer 21

A transcriptional activator protein binds to an activator binding site, allowing RNA polymerase to bind