Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Microbio 3220 > Exam 3 - Lecture 15 > Flashcards

Exam 3 - Lecture 15 Flashcards

1
Q

what are the two approaches to protein regulation?

A
  • regulation of gene expression (transcription/translation)
  • alter activity of enzymes and proteins (posttranslational)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

how is transcription regulated? what kind of genes allow for this regulation?

A

genes aren’t expressed all the time
- constitutive/housekeeping genes
- inducible genes
- repressible genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are inducible genes and what pathways do their enzymes function in?

A
  • genes that are usually off but can be turned on
  • function in catabolic pathways
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what are repressible genes and what pathways do their enzymes function in?

A
  • genes that are usually on but can be turned off
  • function in anabolic pathways
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what reaction does beta-galactosidase catalyze?

A

hydrolysis of lactose into galactose and glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

is the beta-galactosidase gene inducible or repressible? is it on or off in the presence of lactose?

A
  • inducible gene
  • only turned on in the presence of lactose
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

inducible enzymes are only present when their _________ is available

A

substrate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

repressible genes are present unless the _____ _________ of the biosynthetic pathway is available

A
  • end product
  • (no need to make more of the product if it’s available)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

induction and repression occur due to activity of regulatory proteins containing _____ _________ __________

A

DNA binding domains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is negative transcriptional control?

A

binding of a regulatory protein (repressor) at the DNA regulatory site (operator) inhibiting initiation of transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

true or false: repressor proteins can exist in both active and inactive forms

A

true

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what two molecules can alter the activity of repressors?

A

inducers and corepressors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

a repressor is bound to the operator. an inducer binds the repressor, causing it to detach from the operator.

does transcription occur? what kind of regulation is this?

A
  • yes, transcription occurs
  • negative control of an inducible gene
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

a repressor is not bound to the operator. a corepressor binds the repressor, causing it to attach to the operator.

does transcription occur? what kind of regulation is this?

A
  • no, transcription stops
  • negative control of a repressible gene
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is positive transcriptional control?

A

when an activator promotes transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

an activator is not bound to the operator. an inducer binds the activator, causing it to attach to the operator.

does transcription occur? what kind of regulation is this?

A
  • yes, transcription occurs
  • positive control of an inducible gene
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

an activator is bound to the operator. an inhibitor binds the activator, causing it to detach from the operator.

does transcription occur? what kind of regulation is this?

A
  • no, transcription does not occur
  • positive control of a repressible gene
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what represses lactose metabolism in the Lac operon?

A
  • LacI repressor
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what are the three structural genes coding for lactose uptake and metabolism?

A

lacZ, lacY, and lacA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what are the three operator binding sites for LacI tetramers? how does LacI bind?

A
  • O1, O2, and O3
  • binds TWO of the three sites; (always binds O1) O1 and O2 or O1 and O3
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

how does LacI block RNA polymerase from binding?

A
  • it bends the DNA which blocks RNA pol from binding the operator
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what binds the LacI repressor causing it to no longer bind to the operator?

A

allolactose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

in the absence of lactose, does LacI bind to the operator?

A

yes

24
Q

in the presence of lactose, does LacI bind to the operator?

A

no

25
Q

what is the protein that positively regulates the lac operon?

A

catabolite activator protein (CAP)

26
Q

CAP regulates the lac operon in response to the presence or absence of _________

A

glucose

27
Q

do cells prefer lactose or glucose?

A

glucose

28
Q

when glucose if present, will the lac operon be activated?

A

no; the cells prefer glucose and don’t need to use lactose

29
Q

what are the two conditions required for activation of lac operon?

A
  • absence of (or low) glucose
  • presence of (or high) lactose
30
Q

the Tryptophan (trp) operon only functions in the _________ of tryptophan

A

absence

31
Q

what kind of control does the trp repressor do for the trp operon?

A

negative control

32
Q

how many structural proteins does the trp operon code for?

A

5

33
Q

what is attenuation (in the trp operon)? what structures allow for this to occur?

A
  • the termination of transcription within the leader region, ending transcription before the gene is transcribed
  • occurs through stem-loop structures in the mRNA depending on the levels of trp present
34
Q

the trp leader sequence contains a short peptide called:

A

TrpL

35
Q

if the amount of charged Trp tRNA is low, does transcription stop or continue? where does the antiterminator loop form on the trp mRNA?

A
  • it continues
  • antiterminator: regions 2 & 3
36
Q

what two regions on the trp mRNA form the transcription terminator?

A

regions 3 & 4

37
Q

riboswitches are a specialized form of transcription ____________

A

attenuation

38
Q

what does folding of the mRNA leader sequence (riboswitch) determine?

A

whether transcription will continue or terminate

39
Q

binding of what alters the folding response of the riboswitch?

A

an effector molecule to the mRNA

40
Q

what is a regulon?

A

a set of genes or operons controlled by a common regulatory protein

41
Q

what is an example of a global regulator in the lac operon?

A

CAP

42
Q

many genes and operons are turned on or off in response to:

A

environmental conditions

43
Q

what are four regulation mechanisms global regulatory systems often use? which is the most common*?

A
  • two component signal transduction systems*
  • phosphorelay systems
  • regulatory systems
  • alternative sigma factors
44
Q

how many domains of life are two component regulatory systems found in?

A

all three

45
Q

what are the two proteins found in the two component regulatory system?

A
  • sensor kinase (histidine kinase)
  • response-regulator protein
46
Q

what are the characteristics of sensor kinase (histidine kinase)?

A
  • extracellular receptor for sensing
  • intracellular communication domain
47
Q

what are the characteristics of the response-regulator protein?

A
  • intracellular protein
  • activated by sensor kinase
  • DNA binding protein (activator/repressor)
48
Q

activation of ________ ________ results in the phosphorylation of its histidine

A

sensor kinase

49
Q

the ___________-__________ ________ is activated by sensor kinase

A

response-regulator protein

50
Q

when the response-regulator protein is activated, a phosphate group is transferred from _____ to _____

A

His to Asp

51
Q

EnvZ is a _________ ________ that phosphorylates in ______ osmolarity

A

sensor kinase; high osmolarity

52
Q

OmpR is a ___________ __________ that regulates transcription when phosphorylated

A

response regulator

53
Q

expression of what two outer membrane proteins do OmpR and EnvZ regulate? what is their regulation dependent on?

A
  • OmpC and OmpF
  • depends of osmolarity
54
Q

match the following:

  1. OmpF
  2. OmpC

a. dominant when E. coli is in high osmolarity
b. dominant when E. coli is in dilute environment

A

1b. OmpF: dominant when E. coli is in dilute environment
2a. OmpC: dominant when E. coli is in high osmolarity

55
Q

which is usually the protein that is on: OmpF or OmpC?

A

OmpF

56
Q

match the following:

  1. OmpR represses
  2. OmpR activates

a. ompF
b. ompC

A

1a: OmpR represses ompF
2b: OmpR activates ompC

Microbio 3220 (24 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions