Chapter 12 part 1 Flashcards
_______ occurs or genes needed to continuously perform tasks and are needed for life of the cell
constitutive transcription
_______ is needed in genes only needed for respones to changing environemental conditions or during certain phases of growth
regulated transcription
_______ regulation is the major means of regulating gene expression in bacteria
- some _______ mechanisms are also important
transcriptional
post-transcriptional
negative control of transcription involves binding of a(n) _______ protein to a regulatory DNA sequence and preventing transcription
repressor
positive control of transcription involves binding of a(n) _______ protein to a regulatory DNA sequence and initiates transcription
activator
Transcription factors all have at least 2 domains. What are they?
1) DNA binding domain
2) allosteric domain
_______ domain locates and binds to operator DNA sequence or their target DNA sequences
DNA binding domain
_______ domain binds a molecule or protein, which causes a change in conformation of the DNA-binding domain, altering its function
allosteric domain
_______ regulation is where the effector molecule causes transcription to start
inducible
_______ regulation is where the effector molecule causes transcription to stop
repressible
In negative inducible control:
1) TF is a _______
2) binding of the effector molecule causes transcription to _______
3) effector molecule is a _______
1) repressor
2) start
3) inducer
In negative repressible control:
1) TF is a _______
2) binding of the effector molecule causes transcription to _______
3) effector molecule is a _______
1) repressor
2) stop
3) co-repressor
In positive inducible control:
1) TF is a _______
2) binding of the effector molecule causes transcription to _______
3) effector molecule is a _______
1) activator
2) Start
3) inducer
In positive repressible control:
1) TF is a _______
2) binding of the effector molecule causes transcription to _______
3) effector molecule is a _______
1) activator
2) stop
3) inhibitor
Bacterial regulatory DNA sequences frequently have _______ or _______ repeats; each polypeptide of a regulatory homodimer interacts with one repeat
inverted or direct
What is the most common structure of a homodimer protein in bacteria?
helix-turn-helix (HTH) motif
clusters of genes undergoing coordinated transcriptional regulation by a shared regulatory region are called _______
operons
the _______ operon of E.coli is responsible for producing three proteins needed for use of lactose
Lactose (lac) operon
_______ is the principal source of energy for E.coli and most organisms, while _______ is one of the sugar/carbon alternate sources
glucose
lactose
Lactose is a disaccharide of _______ and _______
glucose and galactose
Bacteria with a lac+ phenotype can grow on media containing _______ as the only sugar, while the lac- phenotype cannot
lactose
bacteria produce a gated channel, _______, at the cell membrane that allows lactose to enter the cell and the enzyme _______ to break the β-galactoside linkage
permease
β-galactosidase
the breakdown of lactose also produces a small amount of _______, which acts as an inducer compound
allolactose
What are the three binding sites in the regulatory region of E.coli
1) CAP binding site
2) promotor (RNA pol)
3) operator (lac repressor protein)
_______ gene, which encodes β-galactosidase
lacZ
________ gene, which encodes permease
lacY
_______ gene, which encodes transacetylase
lacA
An enzyme that protects the E. coli cell from harmful by-products of lactose metabolism is _______
transacetylase
lacZ, lacY, and lacA are transcribed as a single _______mRNA, which is translated to produce the three distinct polypeptides
polycistronic
The _______ gene encodes for the lac repressor protein
lacI
The lacI gene is next to but not apart of the lac operon and is _______ expressed
constitutively
The lac repressor protein is a _______. (shape)
homo-tetramer
The Lac operon is an example of _______ control
negative inducible
when allolactose binds to the allosteric domain of the lac repressor, the complex is called _______ complex
inducer-repressor
