Module 6 - Regulation of Gene Expression Flashcards

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1
Q

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

A

Constitutive Expression

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2
Q

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

A

Inducible Expression

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3
Q

What controls the initiation of transcription?

A

Binding of RNA polymerase to the promoter

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4
Q

How do organisms regulate the activity of enzymes?

A

By altering their structure and therefore their binding properties

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5
Q

What method is used to shut down a pathway?

A

Allosteric Inhibition

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6
Q

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

A

Covalent Modification

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7
Q

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

A
  • Allosteric Inhibition

- Covalent Modification

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8
Q

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

A

Regulate transcription of the genes that encode these enzymes

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9
Q

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

A
  • Energy

- Resources

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10
Q

What does the production of an enzyme begin with?

A

Gene transcription

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11
Q

What occurs as a result of gene transcription?

A

mRNA is translated subsequently to protein

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12
Q

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

A

RNA polymerase to bind to the promoter on DNA

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13
Q

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

A

The amount of transcription that occurs

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14
Q

What two things are not produced when transcription is prevented?

A

mRNA and proteins

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15
Q

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

A

Several

  • Control of transcription
  • Control of translation
  • Activation/inhibition of final gene product
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16
Q

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

A

Promoter

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17
Q

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

A

Less well

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18
Q

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

A

Weak promoters

19
Q

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

A

Activator proteins

20
Q

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

A

Repressor proteins

21
Q

What is a transcriptional unit also called?

A

Operons

22
Q

What two things does an operon need to consist of?

A
  • Consecutive series of structural genes that code for polypeptides, transcribed from a single promoter
  • Regulatory DNA elements that affect their transcription
23
Q

Polycistronic operons encode for how many polypeptides?

A

More than one

24
Q

How many polypeptides does mRNA transcript code for in eukarya?

A

1

25
Q

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

A
  • lacZ
  • lacY
  • lacA
  • Operator
26
Q

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

A

Operator

27
Q

What is the product and function of lacZ gene?

A
  • Permease

- Facilitates the uptake of lactose

28
Q

What is the product and function of lacY gene?

A
  • B-galactosidase

- Facilitates enzymatic breakdown

29
Q

What is the product and function of lacA gene?

A
  • B-galactoside transacetylase

- Unknown role

30
Q

What controls the initiation of transcription in an operon?

A

Single promoter

31
Q

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?

A

Regulatory proteins

32
Q

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

A

Negative control

33
Q

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

A

Positive control

34
Q

What two things do higher rates of transcription result in?

A
  • Higher levels of mRNA transcript

- Protein production

35
Q

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

A

Negative control

36
Q

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

A

Repressor binding to the operator

37
Q

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

A

Effectors

38
Q

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

A

Allosteric regulation

39
Q

What are two kinds of effector molecules?

A
  • Inducers

- Compressors

40
Q

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

A

Inducers

41
Q

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

A

Corepressors

42
Q

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

A

Absence

43
Q

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

A

Presence