chapter 11 (from quizlet) Flashcards
Are expression of genes that are constitutive regulated?
No, unregulated
What is an effector molecule?
A small molecule that binds to an enzyme to regulate its activity
How is chemotaxis regulated?
By a series of signal transduction events
What is the function of methyl-accepting chemotaxis proteins? (MCPs)
To sense the presence of a specific chemical
What is required for transcription that is regulated by positive control?
activator protein
The expression of genes required for biofilm formation occurs only after a cell has attached to a surface that is suitable for biofilm development. What is this type of gene expression called?
induction
What would characterize the phenotype of a CheY mutant?
smooth swimming
What would characterize the phenotype of a CheB mutant?
constant tumbling
During negative regulation of gene expression the repressor protein binds to the operator to inhibit transcription. What is the effector molecule that controls the activity of the repressor protein called?
corepressor or inducer
What controls the expression of the lac operon?
both repression and activation mechanisms
How will E. coli growing in a medium containing both lactose and glucose react?
by preferentially utilizing glucose first
Mutants that constitutively expressed β-galactosidase were placed into two different groups. Where were the mutations for constitutive expression located?
In either the lacI gene or operator region
When does repression of the lac operon occur?
When the repressor protein binds to the operator region.
A mutation in the lacI gene results in an active repressor protein that can no longer bind allolactose. Which would be true of the phenotype of the mutant strain?
it would repress β-galactosidase when lactose is present.
Isopropyl β-d-1- thiogalactopyranoside (IPTG), a lactose analog, acts as an inducer of the lac operon. What is its mode of action?
It inactivates the LacI repressor protein
Attenuation is a regulator mechanism in bacteria that relies on what?
transcription and translation occurring simultaneously
What is typically involved in a two-component regulatory system?
histidine kinase and a response regulator
What component of the two-component regulatory system frequently senses changes in the external environment?
histidine kinase
The transfer of T-DNA into a plant cell by Agrobacterium tumefaciens is a highly regulated process. This process only occurs if a plant becomes wounded and excretes various compounds that are detected by A. tumefaciens for expression of its virulence genes. Regulation of virulence gene expression is under the control of which type of system?
A two-component system
How is quorum sensing, a type of cell to cell communication, mediated?
by chemical signaling
What autoinducer is used by many Gram-negative bacteria?
a homoserine lactone derivative
Once the autoinducer excreted by Vibrio fischeri reaches a critical concentration, it is able to diffuse back into the cell. What is the next action?
bind to transciptional activator protein to activate transcription of the lux genes
What is the term for a large group of genes whose expression is under the control of a single regulatory system?
regulon
What is a “reporter gene”?
the fusion of a promoter region of interest to a gene whose product can easily be measured
What is true of catabolite repression?
it results in diauxic growth
The catabolite activator protein (CAP) activated transcription of the lac operon when it binds this coactivator
cylic-AMP
What does sigma factor helps the RNA polymerase do?
identify the promoter region of a gene
The use of a sigma factor of RNAP for promoter identification is a type of what?
global regulation
Small non-coding RNA molecules (sRNA) affect gene expression at the level of:
translation
