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MICR 4423 (ACTUAL 2025/2026) EXAM 5 QUESTIONS
WITH 100% VERIFIED CORRECT ANSWERS
What is antibiotic selection? - (answers)Survival of a population of antibiotic
resistant cells within a larger population of antibiotic sensitive cells.
Where can antibiotic selection occur? - (answers)Anywhere where there are
antibiotics and bacteria present. The best-surviving bacteria will be selected for.
Name a common use for antibiotic selection in microbiological research. -
(answers)To identify and isolate cells that have piece of DNA of interest such as a
particular plasmid or gene in the chromosome.
Why does virtually every plasmid used for scientific research contain an antibiotic
resistance marker? - (answers)It allows the cells that contain that plasmid to be
identified through antibiotic selection.
Imagine that you have a sample of bacteria that is a mixture of ampicillin-resistant
cells and ampicillin-sensitive cells. How could you isolate the ampicillin-resistant
cells? - (answers)Plate the cells on an ampicillin plate so that only the ampicillin-
resistant cells will survive and produce colonies.
What antibiotic or class of antibiotics do cells containing the bla marker become
resistant to? What about aac? What about cat? - (answers)Bla- ampicillin/any
cillin
Aac- aminoglycosides (usually kanamycin)
Cat- chloramphenicol
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What are the Tet-ON and Tet-OFF systems typically used for? - (answers)To
inducibly or conditionally control gene expression in eukaryotic systems.
What is a typical inducer of the Tet-ON or Tet-OFF system? - (answers)Plain
tetracycline or (usually doxycycline)
Distinguish between the Tet-ON and Tet-OFF systems in terms of what inducer
addition does to gene expression and how it occurs at the molecular level. -
(answers)In Tet-ON when you add tet or dox it turns gene expression on. In Tet-
OFF when you add tet or dox it turns tet expression off. Addition of tetracycline
always causes tetR to come off its operator. In Tet-OFF there is a cruddy promoter
that requires a transactivation domain which is bound to TetR. When TetR leaves
it takes the transactivation domain with it and stops gene expression.
What is a typical way of administering Tet to an animal? - (answers)Through its
drinking water.
Contrast how antibiotics are regulated in the United States and northern Europe
with how they are regulated in most other countries. - (answers)In US- prescribed
by a doctor and dispensed by a pharmacist.
Most other countries- over-the-counter in drug stores or even gas stations.
List at least one pro and one con of having antibiotics available by prescription
only. - (answers)Prescription only pro- professional diagnosis means hopefully the
MICR 4423 (ACTUAL 2025/2026) EXAM 5 QUESTIONS
WITH 100% VERIFIED CORRECT ANSWERS
What is antibiotic selection? - (answers)Survival of a population of antibiotic
resistant cells within a larger population of antibiotic sensitive cells.
Where can antibiotic selection occur? - (answers)Anywhere where there are
antibiotics and bacteria present. The best-surviving bacteria will be selected for.
Name a common use for antibiotic selection in microbiological research. -
(answers)To identify and isolate cells that have piece of DNA of interest such as a
particular plasmid or gene in the chromosome.
Why does virtually every plasmid used for scientific research contain an antibiotic
resistance marker? - (answers)It allows the cells that contain that plasmid to be
identified through antibiotic selection.
Imagine that you have a sample of bacteria that is a mixture of ampicillin-resistant
cells and ampicillin-sensitive cells. How could you isolate the ampicillin-resistant
cells? - (answers)Plate the cells on an ampicillin plate so that only the ampicillin-
resistant cells will survive and produce colonies.
What antibiotic or class of antibiotics do cells containing the bla marker become
resistant to? What about aac? What about cat? - (answers)Bla- ampicillin/any
cillin
Aac- aminoglycosides (usually kanamycin)
Cat- chloramphenicol
, 2|Page
What are the Tet-ON and Tet-OFF systems typically used for? - (answers)To
inducibly or conditionally control gene expression in eukaryotic systems.
What is a typical inducer of the Tet-ON or Tet-OFF system? - (answers)Plain
tetracycline or (usually doxycycline)
Distinguish between the Tet-ON and Tet-OFF systems in terms of what inducer
addition does to gene expression and how it occurs at the molecular level. -
(answers)In Tet-ON when you add tet or dox it turns gene expression on. In Tet-
OFF when you add tet or dox it turns tet expression off. Addition of tetracycline
always causes tetR to come off its operator. In Tet-OFF there is a cruddy promoter
that requires a transactivation domain which is bound to TetR. When TetR leaves
it takes the transactivation domain with it and stops gene expression.
What is a typical way of administering Tet to an animal? - (answers)Through its
drinking water.
Contrast how antibiotics are regulated in the United States and northern Europe
with how they are regulated in most other countries. - (answers)In US- prescribed
by a doctor and dispensed by a pharmacist.
Most other countries- over-the-counter in drug stores or even gas stations.
List at least one pro and one con of having antibiotics available by prescription
only. - (answers)Prescription only pro- professional diagnosis means hopefully the
