mcb3020 4a 2
The lac operon is composed of ___ (number) structural genes that encode enzymes that act to catabolize lactose.
3
Riboswitches contain effector-binding elements at the ____ of the mRNA. Multiple choice question. 5' end AT-rich middle G-rich middle 3' end GC-rich middle
5' end
The adenyl cyclase enzyme converts _____ to cAMP and PPi. Multiple choice question. ATP ADP GTP AMP
ATP
Which two of the following are characteristics of transcriptional regulatory proteins? Multiple select question. Bind to RNA Bind to palindromic DNA sequences Are transmembrane proteins Bind to DNA
Bind to palindromic DNA sequences Bind to DNA
The catabolite activator protein binds to a specific DNA sequence called the ___ recognition site.
CAP or catabolite activator protein
Catabolite operons cannot be transcribed unless the catabolite activator protein is bound to the ____. Multiple choice question. operator sequence CAP recognition site leader activation sequence Shine-Dalgarno sequence
CAP recognition site
Which two of the following are characteristics of the lac repressor protein? Multiple select question. Composed of four identical subunits Composed of two identical subunits Each monomer has a helix-turn-helix domain Has an arabinose binding site
Composed of four identical subunits Each monomer has a helix-turn-helix domain
Which two of the following are characteristics of the lac repressor protein? Multiple select question. Composed of four identical subunits Has an arabinose binding site Each monomer has a helix-turn-helix domain Composed of two identical subunits
Composed of four identical subunits Each monomer has a helix-turn-helix domain
Which of the following is NOT a characteristic of regulatory proteins? Multiple choice question. Responsible for processes such as induction and repression Individual subunits associate to form dimers Controls which molecules can be transported across a biological membrane Binds to palindromic sequences on DNA
Controls which molecules can be transported across a biological membrane
True or false: The lac operon is an example of a positive control system, implying that it is turned "on" until turned "off" by its regulatory protein. True false question. True False
False
True or false: The trp operon is an example of a positive control system. True false question. True False
False
What is the name given to genes whose protein products must be present all the time? Multiple choice question. Housekeeping genes Structural genes Developmental genes Regulatory genes
Housekeeping genes
The first processes that regulate gene expression to be understood in detail were Multiple select question. Phosphorylation Methylation Induction Degradation Repression
Induction Repression
Which two of the following conditions must exist to fully induce the lac operon? Multiple select question. Shortage of tryptophan Lack of preferred carbon and energy source Lactose present in the medium Glucose present in the medium Excess of preferred carbon and energy source Excess of tryptophan
Lack of preferred carbon and energy source Lactose present in the medium
Under which condition is adenyl cyclase active? Multiple choice question. Lactose is present at levels high enough to support the cell's carbon and energy needs Little or no glucose is available Little or no lactose is present Glucose is present at levels high enough to support the cell's carbon and energy needs
Little or no glucose is available
Which of the following terms indicates that the binding of a repressor protein to DNA inhibits transcription initiation? Multiple choice question. Negative transcriptional control Feedback inhibition Competitive inhibition Positive transcriptional control
Negative transcriptional control
Which statement best describes the lac operon in E. coli? Multiple choice question. Positive transcriptional control of repressible genes (i.e.,"on" until turned "off") Negative transcriptional control of inducible genes (i.e., turned "off" until turned "on") Constitutively expressed genes (i.e., always "on")
Negative transcriptional control of inducible genes (i.e., turned "off" until turned "on")
When transcription initiation is promoted by an activator protein binding to DNA, it is termed ___ transcriptional control.
Positive
Which of the following terms indicates that the binding of an activator protein to DNA promotes transcription initiation? Multiple choice question. Reverse transcription Feedback activation Negative transcriptional control Positive transcriptional control
Positive transcriptional control
Which two of the following conditions are required for full activation of the lac operon? Multiple select question. Presence of lactose Low levels or absence of lactose Low levels or absence of glucose High levels of glucose
Presence of lactose Low levels or absence of glucose
The transcription of all catabolite operons are regulated by which two of the following? Multiple select question. Riboswitches Attenuation sequences in the mRNA leader Regulatory protein specific to the operon Catabolite activator protein Antisense RNA sequences
Regulatory protein specific to the operon Catabolite activator protein
Which two of the following describe the catabolite activator protein? Multiple select question. Activates specific operons when glucose is available Represses specific operons when glucose is not available Represses specific operons when glucose is available Activates specific operons when glucose is not available
Represses specific operons when glucose is available Activates specific operons when glucose is not available
Transcription of the trp operon is controlled by which two of the following mechanisms? Multiple select question. Activator protein enables initiation Repression of termination by the ribosome Repressor protein inhibits initiation Premature termination through attenuation
Repressor protein inhibits initiation Premature termination through attenuation
Which term is used to describe genes that encode the non-regulatory proteins (enzymes) in an operon? Multiple choice question. Developmental genes Structural genes Repressible genes Inducible genes
Structural genes
Which term is used to describe genes that encode the non-regulatory proteins (enzymes) in an operon? Multiple choice question. Repressible genes Developmental genes Structural genes Inducible genes
Structural genes
Which statement best describes ara operon regulation? Multiple choice question. The ara operon is regulated by both negative and positive transcriptional control. The ara operon is regulated by negative transcriptional control only. The ara operon is regulated by positive transcriptional control only.
The ara operon is regulated by both negative and positive transcriptional control.
A DNA-binding protein that promotes transcription initiation is termed a(n) ___ protein
activator
Proteins that promote transcription initiation by binding to DNA are called Blank______. Multiple choice question. activator proteins binding proteins repressor proteins repair proteins
activator proteins
ATP is converted to cAMP by the enzyme
adenyl cyclase
ATP is converted to cAMP by the enzyme ___ ___
adenyl cyclase
The stringent response is induced when bacterial cells are starved for ______. Multiple choice question. carbohydrates nitrogen amino acids glucose
amino acids
A regulatory process that results in transcription termination within a leader sequence that precedes the structural genes is termed __
attenuation
Termination of transcription elongation before RNA polymerase enters the first structural gene of an operon is called ___. Multiple choice question. attenuation repression reverse transcription activation
attenuation
Transcription of the trp operon is regulated at the level of initiation by the trp repressor, and at the level of elongation by a process called
attenuation
Transcription of the trp operon is regulated at the level of initiation by the trp repressor, and at the level of elongation by a process called ___
attenuation
DNA-bound repressor proteins inhibit the initiation of transcription by either ___ or ___. [Choose two.] Multiple select question. degrading RNA polymerase blocking the binding of RNA polymerase preventing the movement of RNA polymerase removing RNA polymerase from promoter
blocking the binding of RNA polymerase preventing the movement of RNA polymerase
This image shows the molecules involved in transcriptional regulation of the lac operon. Considering the lac repressor (inactive) and CAP (inactive) proteins illustrated here, which carbon sources are available? Multiple choice question. both lactose and glucose glucose but not lactose neither glucose nor lactose lactose but no glucose
both lactose and glucose
Which cyclic nucleotide activates CAP? Multiple choice question. cAMP cTMP ppGpp cGMP
cAMP
Which cyclic nucleotide activates CAP? Multiple choice question. cTMP cGMP ppGpp cAMP
cAMP
The binding of __ to the catabolite activator protein causes it to change to the active form.
cAMP, cyclic adenosine monophosphate, cyclic AMP, or cyclic-AMP
The binding of to ___ the catabolite activator protein causes it to change to the active form.
cAMP, cyclic adenosine monophosphate, cyclic AMP, or cyclic-AMP
In E. coli, the proteins necessary to utilize lactose as an energy and carbon source will not be expressed, even when lactose is present, unless the ___ ____ protein is activated by the absence of glucose in the cell.
catabolite activator
The positive regulatory system called ___ ___ prevents the expression of genes encoding proteins necessary for the utilization of sugars other than glucose when adequate supplies of glucose are present.
catabolite repression
The global control of operons encoding enzymes for the catabolism of carbohydrates that must be modified prior to entering glycolysis is referred to as ____. Multiple choice question. competitive inhibition catabolite repression feedback inhibition carbohydrate repression
catabolite repression
In E. coli, rotation of the flagella in a ________ direction result in a cellular motion called a run. Multiple choice question. clockwise counterclockwise
counterclockwise
When E. coli is grown on medium containing glucose and lactose, a two exponential phase pattern called ___ growth is seen as the glucose is preferentially metabolized.
diauxic
A pattern of bacterial growth with two exponential phases caused by the presence of two sugars in the medium is called ___. Multiple choice question. binary fission diauxic growth phase variation diazotrophic growth
diauxic growth
Riboswitches are regulatory mRNAs that can fold into different patterns based upon ____. Multiple choice question. allosteric regulation of RNA polymerase alternative splicing patterns of the mRNA position of the ribosome on the mRNA direct binding of an effector molecule to mRNA
direct binding of an effector molecule to mRNA
This image shows the molecules involved in transcriptional regulation of the lac operon. Which carbon sources are available when considering the lac repressor (attached) and CAP (attached) proteins illustrated here? Multiple choice question. both lactose and glucose neither glucose nor lactose lactose but no glucose glucose but not lactose
either glucose nor lactose
Two-component signal transduction systems link changes in _________ to gene expression. Multiple choice question. amino acid levels energy levels nucleotide levels environmental conditions
environmental conditions
The term "regulation of ____ expression" refers to the process of controlling transcription and/or translation.
gene
Regulatory systems that simultaneously control the expression of multiple operons or pathways are referred to as ________. Multiple choice question. global regulatory systems secretion systems DNA binding proteins response regulators
global regulatory systems
Adenyl cyclase activity is inversely proportional to the level of ___ in the cell.
glucose
lac operon
glucose absent/lactose present: inactive lac repressor and CAP active glucose/lactose absent: CAP binds, repressor binds
Enzymes that catalyze reactions that are in constant demand in a cell are encoded by genes referred to as ___ genes.
housekeeping
Which two of the following are components or regulatory sequences for the lac operon? Multiple select question. lacI Five structural genes trpR Four structural genes Three structural genes
lacI Three structural genes
The lac operon is expressed at high levels when the sugar __ is available and a preferred source of carbon and energy is lacking.
lactose
Full transcriptional activation of the lac operon requires high levels of the sugar ___ and low levels or the absence of the sugar ___
lactose glucose
This image shows the molecules involved in transcriptional regulation of the lac operon. With the lac repressor (inactive) and CAP proteins (bound) illustrated here, which carbon sources are available? Multiple choice question. glucose but not lactose both lactose and glucose lactose but no glucose neither glucose nor lactose
lactose but no glucose
The trpL operon encodes the ___ peptide and attenuator sequences.
leader
When transcription initiation is inhibited by a repressor protein binding to DNA, it is termed ___ transcriptional control.
negative
The trp operon is best described as an example of the ______. Multiple choice question. negative transcriptional control of inducible genes negative transcriptional control of repressible genes positive transcriptional control of inducible genes positive transcriptional control of repressible genes
negative transcriptional control of repressible genes
Bacterial repressor proteins bind to a DNA sequence called the ___
operator
Bacterial repressor proteins bind to a DNA sequence called the ___.
operator
In bacteria, repressor proteins bind to a specific DNA sequence called the ____. Multiple choice question. operator promoter enhancer terminator
operator
In bacteria, repressor proteins bind to a specific DNA sequence called the ____. Multiple choice question. promoter terminator enhancer operator
operator
Many transcriptional regulatory proteins bind to short, inverted sequences in DNA called __.
palindromes
Short, inverted sequences of bases in DNA are called ____. Multiple choice question. palindromes spliceosomes nucleosomes promoters
palindromes
The mechanism to synthesize cAMP when glucose is absent involves the system for _____. Multiple choice question. induction of a response regulator alternate sigma factor synthesis phosphorylating glucose as it enters the cell the initial steps of the glycolytic pathway
phosphorylating glucose as it enters the cell
Which two of the following are examples of second messengers? Multiple select question. ppGpp dGTP ATP cAMP
ppGpp cAMP
Proteins that are responsible for the induction or repression of enzyme encoding genes are referred to as ___ proteins.
regulatory
Proteins involved in the control of gene expression in processes such as induction and repression are referred to as ____. Multiple choice question. developmental proteins transport proteins structural proteins regulatory proteins
regulatory proteins
A DNA-binding protein that inhibits transcription initiation by binding to an operator is termed a(n) __.
repressor
When ___ proteins bind to the operator they either block the binding of RNA polymerase or inhibit its movement.
repressor
Proteins that inhibit transcription initiation by binding to operator DNA are called ___. Multiple choice question. repressor proteins binding proteins activator proteins termination proteins
repressor proteins
In translational riboswitches, the binding of an effector molecule alters the shape of the mRNA leader sequence and inhibits ___ binding at the Shine-Dalgarno sequence.
ribosome
Genetic regulatory features termed ___can fold into different patterns based upon the binding of an effector molecule to the mRNA.
riboswitches
Flagellar movement in E. coli involves a combination of smooth swimming motions called __, and nonspecific rotations called ___.
runs tumbles
RNA molecules that do not function as mRNA, tRNA, or rRNA are referred to as ___ or noncoding RNAs.
sRNA
__ __ are small molecules produced inside of cells in response to an external signaling event.
second messengers
cAMP, ppGpp, and cyclic dimeric GMP are all examples of ___. Multiple choice question. second messengers riboswitches sRNAs deoxyribonucleotides
second messengers
Producing alternate versions of ________ factors can immediately change the expression of many bacterial genes. Multiple choice question. AHL phosphodiesterase virulence sigma
sigma
The bacterial RNA polymerase core enzyme needs the assistance of a(n) ___ factor to bind to the promoter and initiate transcription. By producing alternate versions of this factor, the expression of gene sets can be rapidly switched.
sigma
Changes in environmental conditions are linked to changes in gene expression by regulatory proteins of two-component ____ ___ systems.
signal transduction
Global regulatory systems are not likely to involve the regulation of _____. Multiple choice question. multiple genes single operons multiple pathways multiple operons
single operons
RNA molecules that do not function as mRNA, tRNA, or rRNA are referred to as or ___ noncoding RNAs.
small
sRNAs are _____. Multiple choice question. standard RNAs S box RNAs synthetic RNAs small RNAs
small RNAs
second messengers are _____ in response to an external signal. Multiple choice question. small molecules produced changes in gene expression proteins that are activated
small molecules produced
The __ response is observed in many bacteria like E. coli when they are starved for amino acids.
stringent
Genes that encode the non-regulatory proteins in an operon are referred to as ___ genes.
structural
The lac repressor is composed of four identical subunits, called a(n) _____. Multiple choice question. quatramer isomer tetramer
tetramer
The term "regulation of gene expression" refers to the processes that controls ____. Multiple choice question. translation and replication replication and transcription transcription and translation
transcription and translation
As a general rule, Gram-negative bacteria use riboswitches to regulate the ___ of mRNA, and Gram-positive bacteria use riboswitches to regulate ___ termination.
translation, transcription
In translational riboswitches, the binding of an effector molecule alters the shape of the mRNA leader sequence and inhibits binding at the Shine-Dalgarno sequence.
trpL
True or false: All catabolite operons are regulated by CAP and a regulatory protein that is specific to each operon. True false question. True False
true
True or false: The ara operon is an example of both a positive and negative control system. True false question. True False
true
True or false: The intracellular level of cAMP depends on the state of a protein that functions in the phosphoenolpyruvate:sugar phosphotransferase system (PTS). True false question. True False
true
