BIOS 252 Practice Exam with Accurate
Which term would be applied to a regulatory condition that occurs when protein is associated
with a particular section of DNA and greatly reduces transcription? - ✔✔negative control
In the diagram below, what type of control, positive or negative, is operating?
-{ }( )-|-structrual gene-
^
{regulatory protien}
makes a transcription. - ✔✔positive control
T/F Under a system of positive control, transcription does not occur unless a regulator molecule
directly stimulates RNA production. - ✔✔True
T/F Under a system of negative control, genetic expression occurs unless some form of
regulator shuts off such expression. - ✔✔True
Which term is used to describe enzymes that are produced only when specific substrates are
present in the environment? - ✔✔inducible: This term best describes enzymes that are
produced only when specific substrates are present in the environment to induce their
production.
Which term refers to a contiguous genetic complex that is under coordinated control? -
✔✔operon
Things to define - ✔✔allosteric
lysogen
attenuation
,prototroph
operon
Cryan experiments with gut microbes
16 interaction
17 interaction
Which of the following mutations could lead to constitutive expression of the genes of the lac
operon? - ✔✔A mutation in the operator sequence. Such a mutation could prevent binding of
the repressor, allowing expression under all conditions.
Which of the following best describes the biological role of the lac operon? - ✔✔It ensures that
a cell dedicates resources to the production of enzymes involved in lactose metabolism only
when lactose is available in the environment. The cell expends energy to produce the proteins
necessary for lactose metabolism only when lactose is present.
T/F The placement of the operator sequence between the promotor and the structural genes is
critical to the proper function of the lac operon. - ✔✔True. When the repressor binds to the
operator, RNA polymerase cannot transcribe the structural genes.
In the lac operon, the product of structural gene lacZ is capable of ________. - ✔✔splitting the
β-linkage of lactose
Which term most appropriately refers to a regulatory protein in prokaryotes? - ✔✔DNA binding
protein
A constitutive mutation in the lac operon may be of several types. Name two types of
constitutive mutations. - ✔✔lacOc, lacI-
T/F Regarding the lactose utilization system in E. coli, a constitutive mutant is one in which the
three enzymes are produced regardless of the presence or absence of lactose. - ✔✔True
,Which of the following is a neurochemical microbes in our gut can make? - ✔✔GABA
Experiments led by Cryan's group found that - ✔✔Mice fed lactobacilllus were more calm,
behaviorally, when measured via a 6 minutes swim test.
When Lyte asked, "Can bacteria cause stress in mice?" he did an experiment that measured: -
✔✔how mice approached ledges of a maze
T/F Dr. Lyte's inital experiments linking the microbiome to behavior were immediately ground-
breaking and game-changing for the field. - ✔✔False
Which of the following terms best characterizes catabolite repression associated with the lac
operon in E. coli? - ✔✔positive control
T/F Lactose is an inducer of the lac operon. - ✔✔True. Lactose indirectly induces or stimulates
the transcription of genes involved in its metabolism.
What would be the effect of a mutation in the lacI gene that prevented the repressor from
binding to lactose? - ✔✔The lac Z, Y, and A genes would not be expressed. If lactose could not
bind to the repressor, the repressor would stay bound to the operator and repress the
transcription of the lac Z, Y, and A genes.
What is the role of glucose in catabolite repression? - ✔✔It decreases the levels of cAMP in the
cell, repressing transcription from the lac operon.Glucose decreases the levels of cAMP in the
cell, preventing formation of the CAP-cAMP complexes necessary for the stimulation of
transcription from the lac operon.
For the genotype,
I + O+ Z+/ F' I - O+ Z+
, which of the following should be entered into the chart?
Genotype
I + O+ Z+/ F' I - O+ Z+
I - Oc Z+/ F'I - O+ Z-
I s Oc Z+/ F'I + O+ Z+
I - O+ Z+/ F' I - O+ Z+
I+ = wild-type repressor
I- = mutant repressor (unable to bind to the operator)
Is = mutant repressor (insensitive to lactose)
O+ = wild-type operator
Oc = constitutive operator (insensitive to repressor)
lactose or no lactose in chart - ✔✔- + (beta gal made when there is lactose)
For the genotype,
I - Oc Z+/ F'I - O+ Z-
which of the following should be entered into the chart?
Genotype
I + O+ Z+/ F' I - O+ Z+
I - Oc Z+/ F'I - O+ Z-
I s Oc Z+/ F'I + O+ Z+
I - O+ Z+/ F' I - O+ Z+
I+ = wild-type repressor
I- = mutant repressor (unable to bind to the operator)
Is = mutant repressor (insensitive to lactose)
Which term would be applied to a regulatory condition that occurs when protein is associated
with a particular section of DNA and greatly reduces transcription? - ✔✔negative control
In the diagram below, what type of control, positive or negative, is operating?
-{ }( )-|-structrual gene-
^
{regulatory protien}
makes a transcription. - ✔✔positive control
T/F Under a system of positive control, transcription does not occur unless a regulator molecule
directly stimulates RNA production. - ✔✔True
T/F Under a system of negative control, genetic expression occurs unless some form of
regulator shuts off such expression. - ✔✔True
Which term is used to describe enzymes that are produced only when specific substrates are
present in the environment? - ✔✔inducible: This term best describes enzymes that are
produced only when specific substrates are present in the environment to induce their
production.
Which term refers to a contiguous genetic complex that is under coordinated control? -
✔✔operon
Things to define - ✔✔allosteric
lysogen
attenuation
,prototroph
operon
Cryan experiments with gut microbes
16 interaction
17 interaction
Which of the following mutations could lead to constitutive expression of the genes of the lac
operon? - ✔✔A mutation in the operator sequence. Such a mutation could prevent binding of
the repressor, allowing expression under all conditions.
Which of the following best describes the biological role of the lac operon? - ✔✔It ensures that
a cell dedicates resources to the production of enzymes involved in lactose metabolism only
when lactose is available in the environment. The cell expends energy to produce the proteins
necessary for lactose metabolism only when lactose is present.
T/F The placement of the operator sequence between the promotor and the structural genes is
critical to the proper function of the lac operon. - ✔✔True. When the repressor binds to the
operator, RNA polymerase cannot transcribe the structural genes.
In the lac operon, the product of structural gene lacZ is capable of ________. - ✔✔splitting the
β-linkage of lactose
Which term most appropriately refers to a regulatory protein in prokaryotes? - ✔✔DNA binding
protein
A constitutive mutation in the lac operon may be of several types. Name two types of
constitutive mutations. - ✔✔lacOc, lacI-
T/F Regarding the lactose utilization system in E. coli, a constitutive mutant is one in which the
three enzymes are produced regardless of the presence or absence of lactose. - ✔✔True
,Which of the following is a neurochemical microbes in our gut can make? - ✔✔GABA
Experiments led by Cryan's group found that - ✔✔Mice fed lactobacilllus were more calm,
behaviorally, when measured via a 6 minutes swim test.
When Lyte asked, "Can bacteria cause stress in mice?" he did an experiment that measured: -
✔✔how mice approached ledges of a maze
T/F Dr. Lyte's inital experiments linking the microbiome to behavior were immediately ground-
breaking and game-changing for the field. - ✔✔False
Which of the following terms best characterizes catabolite repression associated with the lac
operon in E. coli? - ✔✔positive control
T/F Lactose is an inducer of the lac operon. - ✔✔True. Lactose indirectly induces or stimulates
the transcription of genes involved in its metabolism.
What would be the effect of a mutation in the lacI gene that prevented the repressor from
binding to lactose? - ✔✔The lac Z, Y, and A genes would not be expressed. If lactose could not
bind to the repressor, the repressor would stay bound to the operator and repress the
transcription of the lac Z, Y, and A genes.
What is the role of glucose in catabolite repression? - ✔✔It decreases the levels of cAMP in the
cell, repressing transcription from the lac operon.Glucose decreases the levels of cAMP in the
cell, preventing formation of the CAP-cAMP complexes necessary for the stimulation of
transcription from the lac operon.
For the genotype,
I + O+ Z+/ F' I - O+ Z+
, which of the following should be entered into the chart?
Genotype
I + O+ Z+/ F' I - O+ Z+
I - Oc Z+/ F'I - O+ Z-
I s Oc Z+/ F'I + O+ Z+
I - O+ Z+/ F' I - O+ Z+
I+ = wild-type repressor
I- = mutant repressor (unable to bind to the operator)
Is = mutant repressor (insensitive to lactose)
O+ = wild-type operator
Oc = constitutive operator (insensitive to repressor)
lactose or no lactose in chart - ✔✔- + (beta gal made when there is lactose)
For the genotype,
I - Oc Z+/ F'I - O+ Z-
which of the following should be entered into the chart?
Genotype
I + O+ Z+/ F' I - O+ Z+
I - Oc Z+/ F'I - O+ Z-
I s Oc Z+/ F'I + O+ Z+
I - O+ Z+/ F' I - O+ Z+
I+ = wild-type repressor
I- = mutant repressor (unable to bind to the operator)
Is = mutant repressor (insensitive to lactose)
