Module 6 - Regulation of Gene Expression

Question 1

Term used to describe genes that are always active and expressed; are necessary for metabolism and/or production of proteins?

Answer 1

Constitutive Expression

Question 2

Term used to describe genes expression that can be turned on or off as needed?

Answer 2

Inducible Expression

Question 3

What controls the initiation of transcription?

Answer 3

Binding of RNA polymerase to the promoter

Question 4

How do organisms regulate the activity of enzymes?

Answer 4

By altering their structure and therefore their binding properties

Question 5

What method is used to shut down a pathway?

Answer 5

Allosteric Inhibition

Question 6

What method is used to regulate enzyme action by adding a chemical entity (Ex: phosphorylation, methylation)

Answer 6

Covalent Modification

Question 7

What are two ways that enzymes can be quickly deactivated when a rapid response is necessary?

Answer 7

• Allosteric Inhibition

- Covalent Modification

Question 8

Compared to quickly deactivating enzymes, what is the more efficient way to control metabolic pathways?

Answer 8

Regulate transcription of the genes that encode these enzymes

Question 9

What two factors does regulating the transcription of genes help save?

Answer 9

• Energy

- Resources

Question 10

What does the production of an enzyme begin with?

Answer 10

Gene transcription

Question 11

What occurs as a result of gene transcription?

Answer 11

mRNA is translated subsequently to protein

Question 12

Regulatory molecules and DNA-binding proteins affect the ability of what?

Answer 12

RNA polymerase to bind to the promoter on DNA

Question 13

What does the binding of RNA polymerase to the promoter on DNA affect?

Answer 13

The amount of transcription that occurs

Question 14

What two things are not produced when transcription is prevented?

Answer 14

mRNA and proteins

Question 15

Is gene expression controlled only at a select level or several levels?

Answer 15

Several

• Control of transcription
• Control of translation
• Activation/inhibition of final gene product

Question 16

What is another term for the start of a gene in which RNA polymerase binds to DNA?

Answer 16

Promoter

Question 17

Will RNA polymerase bind more well or less well to weak promoters?

Answer 17

Less well

Question 18

Term used to describe those with sequences that differ from the optimal sequence, resulting in a low basal level of activity?

Answer 18

Weak promoters

Question 19

What protein can increase the binding of RNA polymerase to weak promoters?

Answer 19

Activator proteins

Question 20

What protein can obstruct the binding of RNA polymerase to promoters?

Answer 20

Repressor proteins

Question 21

What is a transcriptional unit also called?

Answer 21

Operons

Question 22

What two things does an operon need to consist of?

Answer 22

• Consecutive series of structural genes that code for polypeptides, transcribed from a single promoter
• Regulatory DNA elements that affect their transcription

Question 23

Polycistronic operons encode for how many polypeptides?

Answer 23

More than one

Question 24

How many polypeptides does mRNA transcript code for in eukarya?

Answer 24

1

Question 25

What are the three structural genes that make up a lac operon? In addition to what other factor?

Answer 25

- lacZ - lacY - lacA - Operator

Question 26

What is the term for the DNA sequence to which regulatory proteins can bind?

Answer 26

Operator

Question 27

What is the product and function of lacZ gene?

Answer 27

- Permease | - Facilitates the uptake of lactose

Question 28

What is the product and function of lacY gene?

Answer 28

- B-galactosidase | - Facilitates enzymatic breakdown

Question 29

What is the product and function of lacA gene?

Answer 29

- B-galactoside transacetylase | - Unknown role

Question 30

What controls the initiation of transcription in an operon?

Answer 30

Single promoter

Question 31

What binds to the operator along with associated effector molecules and modulate the ability of RNA polymerase to bind to the promoter and initiate transcription?

Answer 31

Regulatory proteins

Question 32

What is it called when regulatory proteins can inhibit operon transcription?

Answer 32

Negative control

Question 33

What is it called when regulatory proteins can facilitate operon transcription?

Answer 33

Positive control

Question 34

What two things do higher rates of transcription result in?

Answer 34

- Higher levels of mRNA transcript | - Protein production

Question 35

What type of control involves regulatory mechanisms that involve a repressor?

Answer 35

Negative control

Question 36

What action inhibits the binding of RNA polymerase to the promoter in negative control?

Answer 36

Repressor binding to the operator

Question 37

Molecules that are intermediates of the related metabolic pathways are called?

Answer 37

Effectors

Question 38

Effectors interact with repressor proteins and modulate their ability to bind to the operator. This is known as what kind of regulation?

Answer 38

Allosteric regulation

Question 39

What are two kinds of effector molecules?

Answer 39

- Inducers | - Compressors

Question 40

Effector molecule that inhibits the binding of the repressor protein to the operator?

Answer 40

Inducers

Question 41

Effector molecule that enhances binding of the repressor to the operator?

Answer 41

Corepressors

Question 42

Does a presence or absence of lactose block the promoter site when the repressor binds to the operator?

Answer 42

Absence

Question 43

Presence or absence of lactose? Allolactase (metabolite of lactose) binds to the repressor, preventing binding to operator.

Answer 43

Presence