Chapter 18: Gene Regulation

Question 1

What is the difference between an inducible operon and a repressible operon?

Answer 1

A repressible operon is one hat has its transcription on but can be inhibited (repressed) when a specific small molecule binds allosterically to a regulatory protein. An inducible operon is usually off but can be stimulated (induced) when a specific small molecule interacts with a regulatory protein.

Question 2

If a bacterium was in the presence of adequate glucose, the lac operon would be inactive as the bacteria prefers glucose over lactose for cellular respiration. What would happen if there as inadequate glucose, but plenty of lactose present?

Answer 2

G

Question 3

Explain how cCAMP is related to the regulation of the lac operon. How does the regulatory protein CAP act in the presence or absence of cAMP?

Answer 3

H

Question 4

How does the binding of the top core pressure and the lac inducer to their respective repressor proteins alter repressor function and transcription in each case?

Answer 4

G

Question 5

Describe the binding of RNA polymerase, repressors, and active to the lac operon when both lactose and glucose are scarce. What is the effect of these scarcities on transcription of the lac operon?

Answer 5

G

Question 6

A certain mutation in E. coli Bactria changes lac operator so that the active repressor cannot b ins, how would this affect he cells production of B-galactosidase?

Answer 6

G

Question 7

What is meant by differential gene expression? Why is it essential for cell specialization?

Answer 7

G

Question 8

Differentiate among the following terms: chromatin, heterochromatin, histone acetylation, nucleosomes.

Answer 8

I

Question 9

What is DNA methylation? What is the function of this process?

Answer 9

G

Question 10

What is epibenthic inheritance?

Answer 10

F

Question 11

What is the difference between heterochromatin and euchromatin?

Answer 11

H

Question 12

What do the nucleosomes do to DNA?

Answer 12

Had

Question 13

What’s must be done to histone tails to allow gene activation?

Answer 13

E

Question 14

What are Barr Bodies and how is this related to DNA methylation?

Answer 14

H

Question 15

What is genomic imprinting in mammals?

Answer 15

H

Question 16

Describe a transcription initiation complex and what it does.

Answer 16

H

Question 17

What are control elements with reference to control of transcription?

Answer 17

J

Question 18

Explain the difference between general transcription factors and specific transcription factors.

Answer 18

J

Question 19

What is he difference between proximal and distal control elements?

Answer 19

G

Question 20

Explain how bending of DNA by proteins enables enhancers.

Answer 20

H

Question 21

Once mRNA encoding a particular protein reaches the cytoplasm, what are four mechanisms that can regulate the amount of protein that is active in the cell?

Answer 21

G

Question 22

Examine figure 18.11 and suggest a mechanism by which the yellow activator protein comes to be present in the liver cell but not in the lens cells.

Answer 22

G