Theme 3- Module 1 (Modulating Transcription)

Question 1

What are the two requirements needed for prokaryotic development?

Answer 1

1) Nutrient-rich environment (w/ amino acids and carbs)

2) Favourable temp

Question 2

What are housekeeping genes?

Answer 2

Genes that are required all of the time for normal functions; they are always being transcribed and translated

Maintain general cellular activities while the cell responds to changes in the environ

Question 3

What are regulated genes?

Answer 3

Genes that can be turned on and off on an as-needed basis

Question 4

Examples of housekeeping genes?

Answer 4

Genes that are important for:

• structural proteins of the cell
• RNA and DNA polymerases
• ribosomal proteins

Question 5

What is the preferred energy source of E.coli?

Answer 5

Glucose

Question 6

If we grow E.coli cells in an environment that contains both glucose and lactose, what will the bacteria metabolize first?

Answer 6

All of the glucose

Question 7

What activates the switch between glucose and lactose use?

Answer 7

The products of glucose metabolism

Question 8

True or false: as soon as all of the glucose is consumed, bacteria start metabolizing lactose

Answer 8

False

There is a short period of time after all of the glucose is consumed where there is no bacterial growth

Question 9

What two monosaccharides make up the disaccharide, lactose?

Answer 9

Glucose + galactose

Question 10

________ is the enzyme that can metabolize lactose to produce glucose and galactose

Answer 10

B-galactosidase

Question 11

What did Francois Jacob and Jacques Monod investigate?

Answer 11

How E.coli are able to produce the B-galactosidase that is needed for lactose metabolism

Question 12

Describe Jacob and Monod’s experiment

Answer 12

Grew E.coli in a lactose-free medium, added lactose to the medium, and then removed it again. At the same time they measured the amount of B- galactosidase enzyme produced in the cultured cells.

Question 13

What were the results of Jacob and Monod’s experiment?

Answer 13

Found that the amount of B- galactosidase protein produced began to steadily increase in response to the addition of lactose to the growth media and ceased once the lactose was removed.

Question 14

What is meant when you say a gene is “expressed”?

Answer 14

Means that the functional product of the gene is made, modified and activated

(Transcription, translation, and protein modification are complete)

Question 15

What are the three different levels that regulation occurs at?

Answer 15

Transcriptional control

Translational control

Post-translational control (modifications and activation of produced proteins)

Question 16

What does transcriptional regulation control?

Answer 16

The amount of messenger RNA that is produced in the cell

Question 17

How does transcriptional regulation work?

Answer 17

By controlling the binding of proteins (initiation complexes) to the promoter, the cell can either activate or inhibit transcription

Question 18

What affects how much protein is produced in translational regulation?

Answer 18

1) The rate at which translation occurs

2) The stability of the mRNA (if the mRNA is quickly degraded)

Question 19

True or false: the primary sequence of the polypeptide is not an active protein

Answer 19

True

Question 20

What are some mechanisms of post-translational regulation?

Answer 20

• driving the assembly into complexes
• the binding of substrates
• the unmasking of enzymatic domains

These mechanisms allow the polypeptide chain to be folded into a functional three-dimensional structure

Question 21

Which control mechanism is the fastest? Why?

Answer 21

Post-translational regulation

Allows cell to have a stockpile of inactive proteins. A simple modification can turn on all of the inactive proteins very quickly

Question 22

Which control mechanism is the slowest? Why?

Answer 22

Transcriptional regulation

The cell is starting from scratch.

Question 23

In what instances would a cell use transcriptional regulation?

Answer 23

More drastic environmental changes

(i.e. bacterial cells transcriptionally regulate and increase the levels of B- galactosidase gene —> delayed response after glucose depletion)

Question 24

Which control mechanism is the most efficient? Why?

Answer 24

Transcriptional regulation

The cell does not waste any energy or resources making a mRNA or polypeptide unless it really needs to

Question 25

In prokaryotic development, what do you need to put in the “nutrient-rich” environ?

Answer 25

Amino acids
Nucleotides
Carbs
Vitamins

Question 26

Is the regulation of beta-galactosidase due transcriptional, translational, or post-translational modifications?

Answer 26

Transcriptional