Save
Week 9
Save
Share
Learn
Content
Leaderboard
Share
Learn
Created by
Muri
Visit profile
Cards (68)
What enzyme carries out transcription?
RNA polymerase
View source
What is the composition of RNA polymerase in E. coli?
Multiple subunits including
β
and
α
View source
What role do magnesium ions play in transcription?
They are ubiquitous in
nucleic acid
enzymes
View source
Where is the active center of RNA polymerase located?
In the
middle
of the complex
View source
How does RNA polymerase initially move to the promoter of a gene?
By diffusion in the
cytoplasm
View source
What happens when RNA polymerase encounters DNA?
It binds
unspecifically
to the DNA
View source
What does the RNA polymerase complex do after binding to DNA?
Slides along the DNA in a
one-dimensional
walk
View source
What is the role of a promoter in transcription?
It aids
RNA polymerase
to the gene's start
View source
How does the strength of a promoter affect RNA polymerase interaction?
The closer it resembles the
consensus sequence
, the stronger the interaction
View source
What does the σ70 factor do in transcription?
Allows specific interaction with
–10
and
–35
regions
View source
What happens when cells are stressed regarding σ factors?
They
produce
other
σ
factors
View source
What is formed when a promoter is bound by RNA polymerase?
An
open complex
View source
What is the approximate rate of RNA synthesis by RNA polymerase?
30
–
50
nucleotides
per
second
View source
What are the two main mechanisms for termination of transcription?
GC hairpin formation
and
Rho interaction
View source
What is the accuracy of transcription in vivo?
Approximately 1 × 10
−
5
^{-5}
−
5
View source
What is the half-life of mRNA in bacteria?
Approximately 7
minutes
View source
What happens during head-on collisions between replication forks and transcription complexes?
They are highly
problematic
View source
What is the role of activator proteins in transcription?
They help recruit
RNA polymerase
complexes
View source
How do repressor proteins affect transcription?
They prevent
RNA polymerase
binding
View source
What is the regulation of the lactose operon based on?
Several
levels
of regulation
View source
What does permease do in the lactose operon?
Allows
active transport
of lactose into the cell
View source
What happens to lacI when lactose is present?
Lactose binds and changes the
repressor's
shape
View source
What are the two basic forms of transcriptional regulation in bacteria?
Activation of transcription
Repression of transcription
View source
What are the mechanisms of repression in transcription?
Repression by
steric hindrance
Repression by looping
Repression by
modulation
of an
activator
View source
What are the components of the lactose operon?
lacI
(
repressor
)
lacZ
(
β-galactosidase
)
lacY
(permease)
lacA
(O-acetyltransferase)
View source
What is the process of lactose metabolism in the cell?
Lactose enters the cell via
permease
Lactose is
isomerized
into allolactose
Allolactose binds to the
repressor
Transcription of
lac operon
occurs
View source
What are the roles of GreA and GreB in transcription?
They fit into the
secondary channel
of RNA polymerase
Activate
endonuclease activity
to remove mis-incorporated
nucleotides
View source
What are the consequences of backtracking during transcription?
Pauses
elongation
Leads to stable
RNA polymerase
complexes
View source
What is the significance of the consensus sequence in transcription?
Determines the strength of
RNA polymerase
interaction with the
promoter
View source
What are the effects of stress on σ factors in bacteria?
Cells produce
alternative
σ factors for stress responses
View source
What is the role of the σ70 factor in transcription?
Facilitates specific binding of
RNA polymerase
to the
promoter regions
View source
What is the relationship between transcription and replication in bacteria?
Head-on collisions between
replication forks
and
transcription complexes
are problematic
View source
How does the cell regulate the expression of the lactose operon?
Through
activators
and
repressors
that modulate
RNA polymerase
binding
View source
What is the role of the lacI gene?
It produces a
repressor
for the
lac operon
View source
Why is the lacI gene expressed permanently?
It is under control of a weak
promoter
View source
What does the repressor do in the lac operon?
It binds to the
operator
and represses expression
View source
What is the structure of the repressor formed by lacI?
It forms a
tetramer
that binds to the
operator
View source
How does lactose availability affect the lac operon?
Lactose binds the
repressor
, changing its shape
View source
What happens to the repressor when allolactose binds to it?
It will not bind the
operator
anymore
View source
What is the role of the CAP protein in the lac operon?
It allows strong
transcription
when bound
View source
See all 68 cards
See similar decks
4.2.5 Strong and weak acids
AQA GCSE Chemistry > 4. Chemical changes > 4.2 Reactions of acids
28 cards
3.1.12.3 Weak Acids and Bases
AQA A-Level Chemistry > 3.1 Physical Chemistry > 3.1.12 Acids and Bases (A-level only)
159 cards
4.2.5 Strong and weak acids
GCSE Chemistry > 4. Chemical changes > 4.2 Reactions of acids
37 cards
12.3 Strong and Weak Acids and Bases
Edexcel A-Level Chemistry > Topic 12: Acid-Base Equilibria
29 cards
12.3.1 Degree of Ionization
Edexcel A-Level Chemistry > Topic 12: Acid-Base Equilibria > 12.3 Strong and Weak Acids and Bases
29 cards
Week7
57 cards
Week 10/11
144 cards
Week 3
117 cards
Week4
156 cards
Week1 boc
150 cards
Week2
119 cards
Week5
114 cards
Week8
55 cards
Week 5
Week9
17 cards
Week 2
138 cards
week
23 cards
Week 3
26 cards
week 3
36 cards
Week 1
58 cards
Week 3
29 cards
Week 12 (Summary Week)
36 cards