Term
The cytoplasm of a eukaryotic cell is supported and spatially organized by a cytoskeleton of intermediate filaments, microtubules, and actin filaments.
a. True
b. False |
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Definition
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Term
Put the following components of the cytoskeleton in order of increasing diameter.
a. Microtubules < Intermediate filaments < Actin filaments
b. Microtubules < Actin filaments < Intermediate filaments
c. Actin filaments < Microtubules < Intermediate filaments d. Actin filaments < Intermediate filaments < Microtubules
e. Intermediate filaments < Actin filaments < Microtubules |
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Definition
| d. Actin filaments < Intermediate filaments < Microtubules |
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Term
Which of the following is the main function of intermediate filaments?
a. To provide tracks for guiding intracellular transport
b. To enable cells to crawl c. To enable cells to withstand the mechanical stress that occurs when cells are stretched |
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Definition
| c. To enable cells to withstand the mechanical stress that occurs when cells are stretched |
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Term
At which level of the intermediate filament hierarchy is a covalent bond first found?
a. The coiled-coil dimers are held together via covalent bonding
b. The staggered tetramer of two coiled-coil dimers are held together via covalent bonding
c. Two tetramers pack together via covalent bonding
d. Eight tetramers twisted into a ropelike filament and are held together via covalent bonding e. None of the above interactions contains a covalent bond |
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Definition
| e. None of the above interactions contains a covalent bond |
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Term
Which of the following types of intermediate filaments are found in all animal cells?
a. Keratins
b. Vimentin and vimentin-related filaments c. Nuclear lamins
d. Neurofilaments |
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Definition
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Term
Microtubule growing and shrinking, a process called ______________, stems from the intrinsic capacity of tubulin molecules to hydrolyze ____.
a. Dynamic instability; ATP
b. Rapid reassembly; ATP c. Dynamic instability; GTP
d. Rapid reassembly; GTP
e. Dynamic instability; either ATP or GTP |
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Definition
| c. Dynamic instability; GTP |
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Term
In a centrosome, which structures serve as nucleation sites for the formation of microtubules?
a. αβ-tubulin dimers
b. α- and β-tubulin monomers
c. Tubulin protofilaments d. γ-tubulin rings |
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Definition
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Term
Taxol, a drug used both as a cancer chemotherapy as well as in coating stents to prevent restenosis (recurrent narrowing of the coronary artery), is a mitotic inhibitor that works by:
a. Binding to free tubulin molecules and preventing polymerization
b. Binding to microtubules and preventing polymerization
c. Binding to free tubulin and preventing de-polymerization d. Binding to microtubules and preventing de-polymerization
e. None of the above |
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Definition
| d. Binding to microtubules and preventing de-polymerization |
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Term
In eukaryotic cells, directed intracellular movements are generated by motor proteins which use energy derived from repeated cycles of ATP hydrolysis to travel steadily, in a single direction, along either actin filaments or microtubules. a. True
b. False – they only travel along microtubules
c. False – they only travel along actin filaments |
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Definition
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Term
The membrane of the Golgi apparatus is pulled toward the cell center by interacting with the motor protein:
a. Dyneins that pull toward the plus end b. Dyneins that pull toward the minus end
c. Kinesins that pull toward the minus end
d. Kinesins that pull toward the plus end
e. None of the above |
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Definition
| b. Dyneins that pull toward the minus end |
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Term
The hydrolysis of bound ATP to ADP in an actin filament _____ the strength of binding between monomers in the filament. a. Increases
b. Decreases
c. Has no effect on |
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Definition
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Term
Take the following figure where networks of microtubules (M.T.), actin filaments (A.F.), or intermediate filaments (I.F.) were exposed to a shear force and the resulting degree of stretch was measured. Which of the following statements is NOT true?
a. Microtubules networks are easily deformed but cannot withstand excessive force without rupture
b. Intermediate filaments are easily deformed and can withstand large stresses and strains without rupture
c. Actin filaments are less rigid than either microtubules or intermediate filaments d. A, B, and C are all true |
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Definition
| c. Actin filaments are less rigid than either microtubules or |
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Term
Which organelle sequesters Ca2+ inside muscle fibers? a. The nucleus
b. Mitochondria
c. The sarcoplasmic reticulum
d. The Golgi apparatus e. Lysosomes |
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Definition
| c. The sarcoplasmic reticulum |
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Term
Below is the order of events of muscle contraction in terms of the actin-myosin interaction. Put the following transitional energetic events of muscle contraction (i - iv) in order. Attached Released Cocked Force-generating Attached
I. ATP hydrolysis to ADP + Pi
II. Myosin head releases ADP
III. Binding of ATP to myosin head
IV. Myosin head releases Pi |
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Definition
| b. III --> I --> IV --> II |
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Term
Which is the correct order of the cell cycle?
a. S --> G1 --> M--> G2 --> S …
b. G1 --> M --> G2 --> S --> G1 …
c. G1 --> S --> M --> G2 --> G1 …
d. S --> G1 --> G2 --> M --> S … e. None of the above |
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Definition
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Term
Given the cell cycle profile of proliferating, asynchronous cells as measured by flow cytometry, which of the following statements is NOT true? a. Inhibition of DNA synthesis would cause cells to accumulate in stage II
b. Inhibition of mitosis would cause cells to accumulate in stage III
c. Stage I is the longest stage in the cell cycle
d. A, B, and C are correct |
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Definition
| a. Inhibition of DNA synthesis would cause cells to accumulate in stage II |
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Term
Different cyclin-dependent protein kinases (Cdks) trigger different stages of the cell cycle in part because:
a. Their concentrations increase at different stages of the cycle. b. Their activities increase at different stages of the cycle due to cyclin concentrations
c. They are degraded at different stages of the cycle.
d. A and B
e. A, B and C |
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Definition
| b. Their activities increase at different stages of the cycle due to cyclin concentrations |
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Term
What is responsible for triggering DNA replication and ensuring that DNA replication is initiated only once per cell cycle? a. S-Cdk
b. M-Cdk
c. p21
d. p53 |
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Definition
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Term
DNA damage can arrest the cell at a checkpoint in G1 by activating an important checkpoint protein transcription factor known as __________ (which happens to be disrupted in ~50% of all cancer cases).
a. G1/S-Cdk
b. p21 c. p53
d. M-Cdk
e. Cdc25 |
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Definition
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Term
The five stages of mitosis occur in what order?
a. anaphase --> telophase --> prometaphase --> metaphase --> prophase --> cytokinesis
b. prophase --> prometaphase --> metaphase --> anaphase --> telophase --> cytokinesis
c. telophase --> anaphase --> prophase --> prometaphase --> metaphase --> cytokinesis
d. prophase --> metaphase --> prometaphase --> telophase --> anaphase --> cytokinesis
e. anaphase --> prometaphase --> metaphase --> telophase --> prophase --> cytokinesis |
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Definition
| b. prophase --> prometaphase --> metaphase --> anaphase --> telophase --> cytokinesis |
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Term
Microtubules bind to replicated chromosomes (sister chromatids) and segregate them during anaphase. The ____________________ are the microtubules responsible for binding chromosomes, and they attach via the ________________ structure on a mitotic chromosome ?
a. Aster microtubules; kinetochore b. Kinetochore microtubules; kinetochore
c. Interpolar microtubules; kinetochore
d. Aster microtubule; spindle pole
e. Kinetochore microtubules; spindle pole |
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Definition
| b. Kinetochore microtubules; kinetochore |
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Term
Which of the following is/are inherited randomly between daughter cells during cell division?
a. Chromosomes
b. Golgi c. Soluble proteins
d. Both B and C are inherited randomly
e. None of the above are inherited randomly |
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Definition
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Term
Which of the following statements regarding apoptosis is NOT true?
a. Apoptosis involves activation of pro-caspases to active caspases, a family of proteases, and activation of caspases is primarily regulated by members of the Bcl-2 family
b. A cell undergoing apoptosis shrinks and condenses, and cellular DNA is broken into fragments c. Apoptotic cells often spill their contents into the surrounding region triggering the inflammation response of nearby cells
d. An intracellular apoptotic stimulus can cause activation of pro-caspase-9 via the release of cytochrome c from the mitochondrial intermembrane space
e. Apoptotic cells alter their membrane to attract phagocytic cells, which engulf the apoptotic cell |
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Definition
| c. Apoptotic cells often spill their contents into the surrounding region triggering the inflammation response of nearby cells |
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Term
Mitogens stimulate cell proliferation by:
a. Phosphorylating the Rb protein
b. Activating the Rb protein
c. Inactivating the Rb protein
d. A and B e. A and C |
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Definition
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Term
In mature organisms, cell number is controlled as a result of cell proliferation and cell death. An imbalance in the rates of proliferation or cell death can result in disorders of excessive cell accumulation, such as cancer, or disorders of excessive cell loss, such as neurodegenerative diseases. a. True
b. False |
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Definition
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