BIOS 252 COMPREHENSIVE EXAM NEWEST 2024
ACTUAL EXAM COMPLETE 100 QUESTIONS AND
CORRECT DETAILED ANSWERS |ALREADY GRADED A+
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? -
ANSWER: negative control
In the diagram below, what type of control, positive or negative, is operating?
-{ }( )-|-structrual gene-
^
{regulatory protien}
makes a transcription. - ANSWER: positive control
T/F Under a system of positive control, transcription does not occur unless a
regulator molecule directly stimulates RNA production. - ANSWER: True
T/F Under a system of negative control, genetic expression occurs unless some form
of regulator shuts off such expression. - ANSWER: True
Which term is used to describe enzymes that are produced only when specific
substrates are present in the environment? - ANSWER: 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? - ANSWER: operon
Things to define - ANSWER: 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? - ANSWER: 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? -
ANSWER: 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. - ANSWER: 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 ________. -
ANSWER: splitting the β-linkage of lactose
Which term most appropriately refers to a regulatory protein in prokaryotes? -
ANSWER: DNA binding protein
A constitutive mutation in the lac operon may be of several types. Name two types
of constitutive mutations. - ANSWER: 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. - ANSWER: True
Which of the following is a neurochemical microbes in our gut can make? - ANSWER:
GABA
Experiments led by Cryan's group found that - ANSWER: 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: - ANSWER: 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. - ANSWER: False
Which of the following terms best characterizes catabolite repression associated
with the lac operon in E. coli? - ANSWER: positive control
T/F Lactose is an inducer of the lac operon. - ANSWER: 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? - ANSWER: 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? - ANSWER: 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 - ANSWER: - + (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)
O+ = wild-type operator
Oc = constitutive operator (insensitive to repressor)
lactose or no lactose in chart - ANSWER: + +
For the genotype,
I s 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
ACTUAL EXAM COMPLETE 100 QUESTIONS AND
CORRECT DETAILED ANSWERS |ALREADY GRADED A+
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? -
ANSWER: negative control
In the diagram below, what type of control, positive or negative, is operating?
-{ }( )-|-structrual gene-
^
{regulatory protien}
makes a transcription. - ANSWER: positive control
T/F Under a system of positive control, transcription does not occur unless a
regulator molecule directly stimulates RNA production. - ANSWER: True
T/F Under a system of negative control, genetic expression occurs unless some form
of regulator shuts off such expression. - ANSWER: True
Which term is used to describe enzymes that are produced only when specific
substrates are present in the environment? - ANSWER: 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? - ANSWER: operon
Things to define - ANSWER: 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? - ANSWER: 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? -
ANSWER: 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. - ANSWER: 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 ________. -
ANSWER: splitting the β-linkage of lactose
Which term most appropriately refers to a regulatory protein in prokaryotes? -
ANSWER: DNA binding protein
A constitutive mutation in the lac operon may be of several types. Name two types
of constitutive mutations. - ANSWER: 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. - ANSWER: True
Which of the following is a neurochemical microbes in our gut can make? - ANSWER:
GABA
Experiments led by Cryan's group found that - ANSWER: 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: - ANSWER: 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. - ANSWER: False
Which of the following terms best characterizes catabolite repression associated
with the lac operon in E. coli? - ANSWER: positive control
T/F Lactose is an inducer of the lac operon. - ANSWER: 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? - ANSWER: 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? - ANSWER: 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 - ANSWER: - + (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)
O+ = wild-type operator
Oc = constitutive operator (insensitive to repressor)
lactose or no lactose in chart - ANSWER: + +
For the genotype,
I s 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
