Exam 4 part 2
Activators
(?) -> Bind to DNA and increase transcription - positive control refers to regulation by these proteins
Repressors
(?) -> bind to DNA to inhibit transcription - negative control refers to transcriptional regulation by theses proteins.
prevents the cell from wasting energy
A benefit of gene regulation is that encoded proteins are not made when they are not needed. What benefit does this provide?
true
A benefit of gene regulation is that encoded proteins will not be produced when they are not needed.
activator
A corepressor binds to a repressor protein, while an inhibitor binds to an _______ protein.
repressor
A corepressor binds to a repressor protein, while an inhibitor binds to an activator protein.
activator
A corepressor is a small molecule that binds to a repressor protein, thereby causing the protein to bind to the DNA, while an inhibitor binds to a(n) ______ protein and prevents it from binding to the DNA.
repressor
A corepressor is a small molecule that binds to a(n) _______ protein, thereby causing the protein to bind to the DNA, while an inhibitor binds to an activator protein and prevents it from binding to the DNA.
operon
A group of two or more genes under the transcriptional control of a single promoter is termed a(n) ________.
of two or more genes
A polycistronic mRNA contains the sequence(s).....
negative
A protein such as a repressor that inhibits transcription is exerting _______ control of transcription.
Repressor
A protein that binds to a cis acting regulatory DNA element and prevents transcription
Activator
A protein when bound to a cis acting regulatory DNA element, such as a promoter or an enhancer, activates transcription of an adjacent promoter
repressor
A regulatory protein that binds to DNA and inhibits transcription is known as a(n) ______
activator
A regulatory protein that increases the rate of transcription is a(n) _____
Antisense RNA
A second way other than translational repression that can regulate translation with an RNA strand that is complementary to mRNA
Operon
A segment a genes that is controlled by a promoter and structural genes
Corepressors
A small effector molecule that may inhibit transcription and bind to repressors causing them to bind to DNA
polycistronic
An operon encodes a(n) _______ mRNA, an RNA that contains the sequences of two or more genes.
Genes
Bacteria must regulate ______ to survive!
only when confronted with the stress
Certain proteins help a bacterium survive environmental stress such as heat shock. These proteins are required....
Allosteric transition
Change for one conformation of a protein to another
metabolism
Control of gene expression leads to the production of specific proteins to assist bacterial cells in responses to environmental stressors, preparation for cell division, and ______.
Operators
DNA element at one end of an operon that is the binding site for the repressor
I+ is inducible
Examine mutations that inactivate the structural genes for B-galactosidase and permease identifying repressor mutants. What is the conclusion for strain 1?
I+ is inducible
Examine the genetivc evidence for Allosteriy. The repressor constrains a lactose-binding site and I^s super-repressor mutation prevents expression in the presence of the inducer What is the conclusion for strain 1?
I^S is always repressed
Examine the genetivc evidence for Allosteriy. The repressor constrains a lactose-binding site and I^s super-repressor mutation prevents expression in the presence of the inducer What is the conclusion for strain 2?
When bacteria are subject to heat stress Producing enzymes to metabolize specific sugars when those sugars are found in the environment When bacterial cells are getting ready to divide
Genetic control of the production of specific proteins at specific times would occur in....
Synthetic inducer
How did Jacob's and Monod figure out how the lac operon was control? What evidence did they provide for the operator and repressor? -term was used because allolactose is hydrolyzed by B-galactosidase and IPTG is not. -IPGT still binds of repressor
lacl-
In the 1950s, Jacob and Monod, and their colleague Arther Pardee, has identified a few rare mutant strains of bacteria with abnormal lactose adaptation -one type of mutant involved a defect in this gene and designated this term -resulted in the constitutive expression of the lac operon even in the absence of lactose -the term mutations mapped very close to the lac operon
catabolite repression
In the Lac system, Glucose causes _______ _______. Lactose breaks down into glucose and galactose so the presence of glucose stops lac operon expression via a catabolite activator protein (CAP)
Glucose
In the lac system what cannot be present because it causes catabolite repression -lactose breaks down this and galactose so the presence of this stops lac operon expression
Lactose
In the lac system what needs to be present to break down the glucose and galactose so the present glucose stops lac operon expression -via a catabolite activator protein.
Translation
Regulation can occur as the mRNA is translated into protein during ________.
Transcription
Regulation can occur as the mRNA is translated into protein during _________.
Posttranslational changes
Regulation can occur as the protein undergoes _________ _________ to make it a functional protein
Allosteric site
Site on a protein that binds a small molecule causing a change in the conformation of the protein that modifies the activity of its active site (A)
Feedback inhibition
Term for if the concentration of the final product becomes high it will bind to enzyme 1 and inhibit it's ability to convert the substrate into intermediate 1.
Transcriptional regulation
Term for what involves the actions of two main types of regulatory proteins
galactose
The enzyme beta-galactosidase cleaves the sugar lactose into __________ and glucose.
lactose
The exposure of bacterial cells ________ to increases the levels of lactose-utilizing enzymes 100- to 10,000-fold.
Lac operon
The group of genes that help to break down lactose to create glucose for ATP.
regulation
The phenomenon in which the level of gene expression can vary under different conditions is gene ______.
False
The rate of transcription initiation rarely influences overall gene expression.
our initial understanding of gene regulation
The research of Jacob and Monod provided.....
enzyme adaptation
The research of Monod and Jacob that led to the initial understanding of gene regulation stemmed from an interest in......
Lac system
This evolved to maximize energy efficiency. 2 environmental conditions have to be met for lactose metabolites to be expressed... 1. Lactose needs to be present 2. Glucose cannot be present The cell can capture more energy from the breakdown of glucose than other sugars.
Translational regulatory protein
This protein recognized sequences within the mRNA that the translations of mRNA is regulated by the binding of proteins
trpL
This trp operon encodes a short peptide called the leader peptide that functions in attenuation
trpR
This trp operon encodes the trp repressor protein that functions in repression
constitutive
Unregulated genes are also called ______ genes.
constant levels of expression
Unregulated genes have.....
Initiation factors Size of the ribosomes The different tRNAs to start
What are differences between prokaryotes and eukaryotes in translation
lacY lacA lacZ
What are the protein-coding genes in the lac operon?
Repressor
What binds to an operator sequence
Arabinose
What is needed for an Arabinose operon to operate
Permease
gene Y, to transport lactose into the cell
Allosteric effector
A small molecule that binds to the allosteric site
a single promoter
An operon is a group of at least two genes under the transcriptional control of.......
Arabinose operon
An operon that is an example of which a single DNA binding protein may act as either a repressor or an activator
Enzyme adaptation
At the turn of the 20th century, scientists made the following observation... -Francois Jacob and Jacques Monod at the Pasteur Institute in Paris were interested in this phenomenon focusing their attention on lactose metabolism in E. Coli. -a particular enzyme appears in the cells only after the cell has been exposed to the enzymes substrates which is termed...
Inducers
Environmental agent that triggers transcription from an operon
Lac system
Evolved to maximize energy efficiency 2 environmental conditions have to be met for lactose metabolites to be expressed -lactose needs to be present -glucose cannot be present
the rate of transcription initiation
In bacteria, the most common way to regulate gene expression is by influencing.....
Constitutive
Meaning "always on", genes that are unregulated are termed this. They have essentially constant levels of expression. Frequently, these kinds of genes encode proteins that are continuously nescessary for the survival of the organism.
lactose
Monod and Jacob studied ________ metabolism in E. coli.
E. coli
Monod and Jacob studied lactose metabolism in.....
Unregulated genes
These kinds of genes have essentially constant levels of expression in all conditions over time Constitutive genes are also called this...
Eukaryotes
Transitional repression is also found in these organisms
O^c mutation
What would have more effect on Z and Y transcription, an O^c mutation or an I^S mutation?
Inhibitors
A small effector molecules that may inhibit transcription and bind to activators preventing them from binding to DNA
Wild type is inducible
Examine mutations that inactivate the structural genes for B-galactosidase and permease identifying operator mutants. What is the conclusion for strain 1?
Z+ is dominant to Z-
Examine mutations that inactivate the structural genes for B-galactosidase and permease identifying operator mutants. What is the conclusion for strain 2?
O^c is constitutive
Examine mutations that inactivate the structural genes for B-galactosidase and permease identifying operator mutants. What is the conclusion for strain 3?
Operator is cis-acting
Examine mutations that inactivate the structural genes for B-galactosidase and permease identifying operator mutants. What is the conclusion for strain 4?
I- is constitutive
Examine mutations that inactivate the structural genes for B-galactosidase and permease identifying repressor mutants. What is the conclusion for strain 2?
environmental
Examples of a(n)________ stress that might require a bacterium to produce a specific protein include osmotic shock or heat shock.
Repressible
Genes that are regulated by effector molecules utilizing corepressors binding to repressors causing them to bind to DNA and inhibitors to bind to activators preventing them from binding to DNA are termed....
Posttranslational regulation
Known as feedback inhibition being a common mechanism to regulate the activity of metabolic enzymes -the final product in a pathway often can inhibit an enzyme that acts early in the pathway
Effector molecules
Molecules that consist of these small molecules that affect transcription regulation and may inhibit transcription.
Induction
Relief of representation of a gene or set of genes under negative control
Initiation of transcription
The most common was to regulate gene expression in bacteria is by influencing the...... The rate of RNA synthesis can be increases or decreased.
terminator
The operon is flanked by a promoter that signals the beginning of transcription and a(n) ______ that signals the end of transcription.
promoter
The operon is flanked by a(n) _______ that signals the beginning of transcription and a terminator that signals the end of transcription.
Attenuator control region
The trp mRNA leader sequence contains this region and two trp codons
Transitional repressors
These repressors inhibit translation in one of two ways -binding next to the shine-dalgarno sequence and/or the start codon which will sterically hinder the ribosome from initiating translation -binding outside the shine-dalgarno start codon region and they stabilize tand mRNA secondary structure that prevents initiation.
positive
Transcription regulation by an activator protein is considered to be ______ control.
1,000- to 10,000-fold
Exposure of bacterial cells to lactose increases levels of lactose-utilizing enzymes......
I^S is dominant to I+
Examine the genetivc evidence for Allosteriy. The repressor constrains a lactose-binding site and I^s super-repressor mutation prevents expression in the presence of the inducer What is the conclusion for strain 3?
Translational repressors
For some bacterial genes the translation mRNA done by the binding of proteins -translational regulatory protein sequences within the mRNA -in most cases these proteins act to inhibit translation -known as translational regulation
B-galactoside transacetylase
Gene A, which is not needed for lactose metabolism
False
Gene expression is always the same.
B-galactosidase
Gene Z, to modify lactose intolerance also lactose and cleave the lactose molecule to yield glucose and galactose
Nutritional opportunists
Gene regulation in prokaryotes must be able to recognize environmental conditions in which they should activate or repres the transcription of the relevant genes making prokaryotes/bacteria ________ ________. They must be able to toggle on or off, like a switch, the transcription of each specific gene or group of genes.
False
Gene regulation is constant.
Inducible
This type of effector molecule binds to regulatory proteins but not to DNA directly, is a small effector molecule that may increase transcription, and genes that are regulated in this manner are termed....
I+ is dominant to I-
Examine mutations that inactivate the structural genes for B-galactosidase and permease identifying repressor mutants. What is the conclusion for strain 3?
I+ is trans-acting
Examine mutations that inactivate the structural genes for B-galactosidase and permease identifying repressor mutants. What is the conclusion for strain 4?
trp operon
Involved in the biosynthesis of the amino acid tryptophan and has 2 different types -one type encodes the trp repressor protein that functions in repression -another type encodes a short peptide called the leader peptide that functions in attenuation
