MCB 150 Final Exam | Questions with 100% Verified
Answers | Latest Update
Question:
Which of the following drugs works by stabilizing microtubules rather than blocking their formation?
A. Taxol
B. Vinblastine
C. Colchicine
D. Vincristine
E. Colcemid
Answer:
A. Taxol
Question:
Which one of the following statements about microtubules is correct?
A. Tubulin dimers with nucleoside diphosphates in their
nucleotide binding site(s) have a lower affinity for each other than tubulin dimers with nucleoside
triphosphates in their nucleotide binding site(s).
B. In vivo, polymerization of microtubules typically occurs at
the minus end because the plus end is anchored.
C. Myosin is a motor protein that moves toward the plus end
of microtubules.
D. Only the alpha subunit of a tubulin dimer has a nucleotide
binding site.
E. ATP is the nucleotide that occupies the nucleotide binding
site(s) of tubulin dimers.
Answer:
A. Tubulin dimers with nucleoside diphosphates in their nucleotide binding site(s) have a
lower affinity for each other than tubulin dimers with nucleoside triphosphates in their nucleotide
binding site(s).
Question:
Which of the following is a property of microtubules, but not of actin?
A. In vitro, both ends can show dynamic growth
B. Can be used for vesicle transport
C. Subunits are dimeric
D. Can form stable arrangements to support cell projections
E. Polarity at filament ends
Answer:
C. Subunits are dimeric.
Microtubule subunits (tubulin) are dimeric, while actin filament subunits (G-actin) are monomeric.
,Question:
Identify if the following statements regarding microtubule function in a cell are true or false.
Choices: True, False.
1. Microtubules are completely unchanging, stable structures.
2. Cilia are extensions of cytoplasm stabilized by microtubules.
3. During interphase, microtubules typically do not reach the
cell membrane.
4. Microvilli are the same as flagella.
Answer:
1. False
2. True
3. True
4. False
Question:
Decide if the following statements are true or false. Choices: True, False.
1. Tubulin subunits have ATP-binding sites.
2. Colcemid could be used as a muscle relaxant; it would
relieve tension by promoting the degradation of actin filaments.
3. In vivo, microtubules often have their plus end anchored
into the MOC.
4. Vinblastin would be likely to affect a human embryo more
severely than a grown person.
Answer:
1. False. Tubulin subunits have GTP-binding sites.
2. False. Colcemid could be used in the lab to induce depolymerization of microtubules
and non-specifically affects all microtubules.
3. False. In vivo, microtubules have their minus ends anchored into the MTOC.
4. True. Vinblastin induces depolymerization of microtubules and targets rapidly-dividing
cells.
Question:
Treatment of a cell with the drug Colchicine will:
A. promote microtubule depolymerization because the
colchicine will bind the microtubule ends.
B. stabilize microtubule length because colchicine will bind
the microtubule ends.
C. promote microtubule depolymerization because the
effective concentration of tubulin will be too low to sustain polymerization.
D. stop microtubule depolymerization because the free
tubulin will bind the colchicine.
E. promote microtubule polymerization because the
colchicine will bind the microtubule ends.
Answer:
C. promote microtubule depolymerization because the effective concentration of tubulin
will be too low to sustain polymerization.
,Question:
Identify if each of the following statements are true or false. Choices: True, False.
1. Microtubules and tubulin building blocks both have polarity.
2. If the concentration of GTP-bound tubulin is increased,
depolymerization is more likely to occur.
3. The addition of ATP to tubulin will increase the
concentration of ATP bound tubulin and the microtubule will polymerize.
4. Assembly and disassembly of microtubules is typically
fastest at the plus end in a living cell.
Answer:
1. True.
2. False. If the concentration of GTP-bound tubulin is increased, polymerization is more
likely to occur.
3. False. The addition of GTP to tubulin will increase the concentration of GTP-bound
tubulin and the microtubule will polymerize.
4. True. (since the minus end is bound to the MTOC)
Question:
Which of the following statements is TRUE?
A. Axons and dendrites are examples of microvilli.
B. Axons and dendrites are important for the motility of nerve
cells.
C. Microtubules are found in a 9+2 pattern in axons but not
dendrites.
D. Axons and dendrites are anchored in the centrosome of
nerve cells.
E. Axons and dendrites are the cytoplasmic extensions of
nerve cells.
Answer:
E. Axons and dendrites are the cytoplasmic extensions of nerve cells.
Axons are not the same as axonemes.
Question:
Which of the following proteins is responsible for the movements of cilia?
A. Kinesin
B. G-actin
C. Myosin
D. F-actin
E. Dynein
Answer:
E. Dynein
, Question:
From where do microtubules most specifically originate in an animal cell?
A. Centrioles
B. Cytoplasm
C. The cell
D. Centromere
E. Pericentriolar material
Answer:
E. Pericentriolar material
Microtubules emanate from the PCM.
Question:
Identify whether each of the following statements about microtubules is true or false. Choices: True,
False.
1. Both the alpha and the beta subunit of the microtubules
have a GTP binding site.
2. Microtubules are the largest of the cytoskeletal elements,
made up of 25 protofilaments.
3. In a microtubule, the rate of polymerization in vitro is
typically faster at the plus end.
4. Assembly and disassembly is normally fastest at the plus
end in vivo.
Answer:
1. True.
2. False. Microtubules are the largest of the cytoskeletal elements, made up of 13
protofilaments.
3. True.
4. True.
Question:
The behavior in which a microtubule alternates between periods of growth and shrinkage is most
accurately called:
A. recycling.
B. dynamic instability.
C. cytoplasmic streaming.
D. an equilibrium state.
E. treadmilling.
Answer:
B. dynamic instability.
Answers | Latest Update
Question:
Which of the following drugs works by stabilizing microtubules rather than blocking their formation?
A. Taxol
B. Vinblastine
C. Colchicine
D. Vincristine
E. Colcemid
Answer:
A. Taxol
Question:
Which one of the following statements about microtubules is correct?
A. Tubulin dimers with nucleoside diphosphates in their
nucleotide binding site(s) have a lower affinity for each other than tubulin dimers with nucleoside
triphosphates in their nucleotide binding site(s).
B. In vivo, polymerization of microtubules typically occurs at
the minus end because the plus end is anchored.
C. Myosin is a motor protein that moves toward the plus end
of microtubules.
D. Only the alpha subunit of a tubulin dimer has a nucleotide
binding site.
E. ATP is the nucleotide that occupies the nucleotide binding
site(s) of tubulin dimers.
Answer:
A. Tubulin dimers with nucleoside diphosphates in their nucleotide binding site(s) have a
lower affinity for each other than tubulin dimers with nucleoside triphosphates in their nucleotide
binding site(s).
Question:
Which of the following is a property of microtubules, but not of actin?
A. In vitro, both ends can show dynamic growth
B. Can be used for vesicle transport
C. Subunits are dimeric
D. Can form stable arrangements to support cell projections
E. Polarity at filament ends
Answer:
C. Subunits are dimeric.
Microtubule subunits (tubulin) are dimeric, while actin filament subunits (G-actin) are monomeric.
,Question:
Identify if the following statements regarding microtubule function in a cell are true or false.
Choices: True, False.
1. Microtubules are completely unchanging, stable structures.
2. Cilia are extensions of cytoplasm stabilized by microtubules.
3. During interphase, microtubules typically do not reach the
cell membrane.
4. Microvilli are the same as flagella.
Answer:
1. False
2. True
3. True
4. False
Question:
Decide if the following statements are true or false. Choices: True, False.
1. Tubulin subunits have ATP-binding sites.
2. Colcemid could be used as a muscle relaxant; it would
relieve tension by promoting the degradation of actin filaments.
3. In vivo, microtubules often have their plus end anchored
into the MOC.
4. Vinblastin would be likely to affect a human embryo more
severely than a grown person.
Answer:
1. False. Tubulin subunits have GTP-binding sites.
2. False. Colcemid could be used in the lab to induce depolymerization of microtubules
and non-specifically affects all microtubules.
3. False. In vivo, microtubules have their minus ends anchored into the MTOC.
4. True. Vinblastin induces depolymerization of microtubules and targets rapidly-dividing
cells.
Question:
Treatment of a cell with the drug Colchicine will:
A. promote microtubule depolymerization because the
colchicine will bind the microtubule ends.
B. stabilize microtubule length because colchicine will bind
the microtubule ends.
C. promote microtubule depolymerization because the
effective concentration of tubulin will be too low to sustain polymerization.
D. stop microtubule depolymerization because the free
tubulin will bind the colchicine.
E. promote microtubule polymerization because the
colchicine will bind the microtubule ends.
Answer:
C. promote microtubule depolymerization because the effective concentration of tubulin
will be too low to sustain polymerization.
,Question:
Identify if each of the following statements are true or false. Choices: True, False.
1. Microtubules and tubulin building blocks both have polarity.
2. If the concentration of GTP-bound tubulin is increased,
depolymerization is more likely to occur.
3. The addition of ATP to tubulin will increase the
concentration of ATP bound tubulin and the microtubule will polymerize.
4. Assembly and disassembly of microtubules is typically
fastest at the plus end in a living cell.
Answer:
1. True.
2. False. If the concentration of GTP-bound tubulin is increased, polymerization is more
likely to occur.
3. False. The addition of GTP to tubulin will increase the concentration of GTP-bound
tubulin and the microtubule will polymerize.
4. True. (since the minus end is bound to the MTOC)
Question:
Which of the following statements is TRUE?
A. Axons and dendrites are examples of microvilli.
B. Axons and dendrites are important for the motility of nerve
cells.
C. Microtubules are found in a 9+2 pattern in axons but not
dendrites.
D. Axons and dendrites are anchored in the centrosome of
nerve cells.
E. Axons and dendrites are the cytoplasmic extensions of
nerve cells.
Answer:
E. Axons and dendrites are the cytoplasmic extensions of nerve cells.
Axons are not the same as axonemes.
Question:
Which of the following proteins is responsible for the movements of cilia?
A. Kinesin
B. G-actin
C. Myosin
D. F-actin
E. Dynein
Answer:
E. Dynein
, Question:
From where do microtubules most specifically originate in an animal cell?
A. Centrioles
B. Cytoplasm
C. The cell
D. Centromere
E. Pericentriolar material
Answer:
E. Pericentriolar material
Microtubules emanate from the PCM.
Question:
Identify whether each of the following statements about microtubules is true or false. Choices: True,
False.
1. Both the alpha and the beta subunit of the microtubules
have a GTP binding site.
2. Microtubules are the largest of the cytoskeletal elements,
made up of 25 protofilaments.
3. In a microtubule, the rate of polymerization in vitro is
typically faster at the plus end.
4. Assembly and disassembly is normally fastest at the plus
end in vivo.
Answer:
1. True.
2. False. Microtubules are the largest of the cytoskeletal elements, made up of 13
protofilaments.
3. True.
4. True.
Question:
The behavior in which a microtubule alternates between periods of growth and shrinkage is most
accurately called:
A. recycling.
B. dynamic instability.
C. cytoplasmic streaming.
D. an equilibrium state.
E. treadmilling.
Answer:
B. dynamic instability.
