Brainscape's Knowledge GenomeTM

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


See full index

Molecular Biology > Gene expression in Prokaryotes: The Lac and Trp operon > Flashcards

Gene expression in Prokaryotes: The Lac and Trp operon Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

operon

A

a cluster of genes transcribed by the same promoter that gives rise to polycistronic mRNA-genes usually related

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

what is lacZ in the lac operon

A

the gene that codes for the enzyme B-galactosidase

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

what is lacY and lacA

A

permease and acetylase which are enzymes involved in the metabolism

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

what are the functions of lacZ, lacY and lacA in the lac operon

A

hydrolyses lactose to glucose and galactose

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

where does DNA polymerase bind to in the lac operon

A

the promoter region in the lac operon

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

what does LacI code for in the lac operon

A

always codes for the repressor protein (always turned on that binds to the operator region)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the operator region

A

sequence-specific binding protein (SSBP)

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

if there is no lactose, is the lac operon repressed or induced

A

repressed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what binds to the operator region

A

repressor protein

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

what does the binding of the repressor protein to the operator do

A

prevents RNA polymerase from clearing promoter

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

when lactose is present, what occurs

A

binds to repressor and dissociates from the operator

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

what control is the lac operon under

A

negative feedback control

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

what is lactose known as?

A

an inducer (de-repression)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

repressor structure as a tetramer

A

allows cooperative binding of lactose, also binds to symmetrical DNA sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

how is the lac operon under a negative feedback control

A

active operon makes B-gal which consumes lactose when gone the operon switches off, therefore, is self-regulating

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

cis-acting

A

will only regulate DNA to which it is directly joined
-dominant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

cis

A

next to/ alongside/ adjacent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

trans-acting

A

will regulate genes anywhere
-mostly protein transcription factors
-recessive (mostly)

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

trans

A

next to/ alongside/ adjacent

20
Q

what effect does a mutated operator have on the lac operon

A

constitutive effect
-unable to bind to the repressor, would switch the operon on permanently (gene is always switched on)

21
Q

what effect does a mutated repressor have on the lac operon

A

-constitutive effect
-repressor can’t bind to operon so the gene will always be switched on

22
Q

is a mutation in the promoter/operator reversible or non-reversible

A

irreversible

23
Q

what does introducing a wild type repressor to a lac operon

A

can have an effect

24
Q

what is the effect of the introduction of I+ on the lac operon if there is a mutated operator

A

no efect
cis-dominant

25
Q

what is the effect of the introduction of I+ when there is a mutated repressor

A

complements
trans-recessive

26
Q

what inhibits initiation in the lac operon

A

repressor binds to operator

27
Q

what is repressor activity regulated by

A

lactose

28
Q

what is the effect of mutations in regulatory elements

A

cis-acting
cannot be complemented

29
Q

what is the effect of mutations which alter activity of regulatory proteins

A

trans-acting
may affect many genes
can be complemented

30
Q

can prokaryotes use both glucose and lactose in the lac operon

A

no prokaryotes don’t need to make enzymes that metabolise lactose when glucose is present

31
Q

what is catabolite repression

A

-where several operons allowing the use of alternate carbon sources are repressed by glucose and only become active when all glucose is used up
-preferential use of glucose

32
Q

what does RNA polymerase depend on

A

another protein to bind to the promoter which is CRP

33
Q

CRP

A

catabolite repressor protein or catabolite activator protein

34
Q

what allows CRP to bind to DNA

A

cAMP

35
Q

what is the effect of no cAMP

A

no CRP therefore no binding of DNA

36
Q

effect of high glucose on cAMP

A

low cAMP so lac operon is off, even if lactose is available

37
Q

effect of low glucose on cAMP

A

high cAMP so lac operon is on if lactose is present

38
Q

what is glucose used as in catabolite repression

A

used as a carbon source

39
Q

Trp operon

A

contains genes for the synthesis of amino acids tryptophan

40
Q

Trp repressor

A

binds to the operator in the presence of tryptophan and prevents transcription

41
Q

what pathway is the trp operon

A

biosynthetic pathway

42
Q

what pathway is the lac operon

A

metabolic pathway

43
Q

what do the products of biosynthetic pathways repress

A

their own synthesis

44
Q

what do substrates for metabolic pathways activate

A

their metabolic pathways

45
Q

what is the trp operon repressed by

A

tryptophan (biosynthetic product)

Molecular Biology (5 decks)

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