Page 1 of 31
2025/2026 CELL BIOLOGY EXAM 3 CURRENTLY
TESTING QUESTIONS AND CORRECT DETAILED
ANSWERS (VERIFIED) FOR GUARANTEED
PASS/TOP-RATED A+.
CELL BIOLOGY
Ace your Cell Biology exam with this comprehensive guide,
designed to master essential concepts including cellular
structure, metabolic pathways, and membrane transport
mechanisms. This resource provides high-yield practice
questions and detailed explanations that reinforce key
principles for both lecture and lab assessments.
What causes catastrophe of the microtubule in vitro? ......
ANSWER ....... GTP hydrolysis
What is the role of GTP in microtubule polymerization? ......
ANSWER ....... GTP stabilizes the tip of the microtubule,
allowing more monomers to be added.
What would happen in the treadmilling experiment if a non-
hydrolyzable analogue of GTP were used? ...... ANSWER
....... The microtubule would treadmill until the new
tubulin, with non-hydrolyzable GTP, reached the minus
end, and then it would only extend at the plus end.
, Page 2 of 31
What is the difference between the plus and minus ends of
the microtubule in in vitro experiments? ...... ANSWER
....... The plus end has a lower critical concentration for
tubulin heterodimers.3
How would the drug taxol affect the in vitro dynamic
instability and treadmilling experiments? ...... ANSWER
....... Taxol would stabilize the microtubules in both
experiments, leading to polymerization without
catastrophe.
A model helps scientists form testable hypotheses.
What hypothesis was being tested with the ΔFus3 strain?
...... ANSWER ....... Fus3 is required for the signal
transduction pathway leading to shmoo formation.
What hypothesis was being tested with the Δformin strain?
...... ANSWER ....... Formin is required for the signal
transduction pathway leading to shmoo formation.
In addition to testing shmoo formation in the two mutant
strains of yeast, the scientists also tested shmoo formation
in wild-type yeast.
, Page 3 of 31
What is the purpose of including wild-type yeast cells in the
experiment? ...... ANSWER ....... to show normal shmoo
formation under the experimental conditions
When designing an experiment, scientists make predictions
about what results will occur if their hypothesis is correct.
One of their hypotheses was that Fus3 kinase is required for
the signal transduction pathway leading to shmoo
formation. If this hypothesis is correct, what result should
be observed in the ΔFus3 strain? ...... ANSWER ....... The
ΔFus3 strain should not form shmoos, and the cells
should not have a red zone in their walls.
One of their hypotheses was that formin is required for the
signal transduction pathway leading to shmoo formation. If
this hypothesis is correct, what result should be observed in
the Δformin strain? ...... ANSWER ....... The Δformin
strain should not form shmoos, and the cells should not
have a red zone in their walls.
The micrographs shown below were taken of wild-type,
ΔFus3, and Δformin cells after they were stained green,
exposed to mating factor, and then stained red.
, Page 4 of 31
For each micrograph, drag the labels to answer the
questions. Labels may be used once, more than once, or not
at all. ...... ANSWER ....... Wild Type: Red Green - Asym -
Y-Y-Y
ΔFus3: Yellow - Sym - N - Y - Y
Δformin: Yellow - Sym - N - Y - Y
Fus3 kinase and formin proteins are generally distributed
evenly throughout a yeast cell. Based on the model in the
diagram, why does the shmoo projection emerge on the
same side of the cell that bound the mating factor? ......
ANSWER ....... The only formin molecules that get
phosphorylated and thus activated are those near the G
protein-coupled receptor that binds mating factor.
What do you predict would happen if the yeast had a
mutation that prevented the G protein from binding GTP?
...... ANSWER ....... No shmoo would form in response to
mating factor.
Involved in muscle contraction ...... ANSWER ....... MF
Involved in the movement of cilia and flagella ......
ANSWER ....... MT
2025/2026 CELL BIOLOGY EXAM 3 CURRENTLY
TESTING QUESTIONS AND CORRECT DETAILED
ANSWERS (VERIFIED) FOR GUARANTEED
PASS/TOP-RATED A+.
CELL BIOLOGY
Ace your Cell Biology exam with this comprehensive guide,
designed to master essential concepts including cellular
structure, metabolic pathways, and membrane transport
mechanisms. This resource provides high-yield practice
questions and detailed explanations that reinforce key
principles for both lecture and lab assessments.
What causes catastrophe of the microtubule in vitro? ......
ANSWER ....... GTP hydrolysis
What is the role of GTP in microtubule polymerization? ......
ANSWER ....... GTP stabilizes the tip of the microtubule,
allowing more monomers to be added.
What would happen in the treadmilling experiment if a non-
hydrolyzable analogue of GTP were used? ...... ANSWER
....... The microtubule would treadmill until the new
tubulin, with non-hydrolyzable GTP, reached the minus
end, and then it would only extend at the plus end.
, Page 2 of 31
What is the difference between the plus and minus ends of
the microtubule in in vitro experiments? ...... ANSWER
....... The plus end has a lower critical concentration for
tubulin heterodimers.3
How would the drug taxol affect the in vitro dynamic
instability and treadmilling experiments? ...... ANSWER
....... Taxol would stabilize the microtubules in both
experiments, leading to polymerization without
catastrophe.
A model helps scientists form testable hypotheses.
What hypothesis was being tested with the ΔFus3 strain?
...... ANSWER ....... Fus3 is required for the signal
transduction pathway leading to shmoo formation.
What hypothesis was being tested with the Δformin strain?
...... ANSWER ....... Formin is required for the signal
transduction pathway leading to shmoo formation.
In addition to testing shmoo formation in the two mutant
strains of yeast, the scientists also tested shmoo formation
in wild-type yeast.
, Page 3 of 31
What is the purpose of including wild-type yeast cells in the
experiment? ...... ANSWER ....... to show normal shmoo
formation under the experimental conditions
When designing an experiment, scientists make predictions
about what results will occur if their hypothesis is correct.
One of their hypotheses was that Fus3 kinase is required for
the signal transduction pathway leading to shmoo
formation. If this hypothesis is correct, what result should
be observed in the ΔFus3 strain? ...... ANSWER ....... The
ΔFus3 strain should not form shmoos, and the cells
should not have a red zone in their walls.
One of their hypotheses was that formin is required for the
signal transduction pathway leading to shmoo formation. If
this hypothesis is correct, what result should be observed in
the Δformin strain? ...... ANSWER ....... The Δformin
strain should not form shmoos, and the cells should not
have a red zone in their walls.
The micrographs shown below were taken of wild-type,
ΔFus3, and Δformin cells after they were stained green,
exposed to mating factor, and then stained red.
, Page 4 of 31
For each micrograph, drag the labels to answer the
questions. Labels may be used once, more than once, or not
at all. ...... ANSWER ....... Wild Type: Red Green - Asym -
Y-Y-Y
ΔFus3: Yellow - Sym - N - Y - Y
Δformin: Yellow - Sym - N - Y - Y
Fus3 kinase and formin proteins are generally distributed
evenly throughout a yeast cell. Based on the model in the
diagram, why does the shmoo projection emerge on the
same side of the cell that bound the mating factor? ......
ANSWER ....... The only formin molecules that get
phosphorylated and thus activated are those near the G
protein-coupled receptor that binds mating factor.
What do you predict would happen if the yeast had a
mutation that prevented the G protein from binding GTP?
...... ANSWER ....... No shmoo would form in response to
mating factor.
Involved in muscle contraction ...... ANSWER ....... MF
Involved in the movement of cilia and flagella ......
ANSWER ....... MT
