Bio 205 exam 4
The end of the microtubule that has alpha-tubulin exposed is the a. (+) end. b. (-) end. c. Both (+) and (-) ends. d. Neither end has alpha-tubulin exposed.
b. (-) end.
What is the difference between a malignant tumor and a metastasis? a. A metastasis does not invade surrounding tissue. b. A metastasis is a tumor in different distant tissue. c. A malignant tumor is not able to invade neighboring tissue. d. A malignant tumor does not proliferate excessively.
b. A metastasis is a tumor in different distant tissue.
In response to an apoptotic stimulus, initiator caspases: A. degrade executioner caspases. B. degrade procaspases. C. cleave and activate executioner caspases. D. cleave a transcription factor to active gene expression.
C. cleave and activate executioner caspases.
Which of the following statements about the cytoskeleton is TRUE? a. Actin filaments and microtubules have an inherent polarity, with a plus end that grows more quickly than the minus end b. the cytoskeleton provides a rigid and unchangeable structure important for the shape of the cell c. the three cytoskeletal filaments perform distinct tasks in the cell and act completely independently of one another d. All eukaryotic cells have actin, microtubules, and intermediate filaments in their cytoplasm
a. Actin filaments and microtubules have an inherent polarity, with a plus end that grows more quickly than the minus end
How is muscle contraction reversed? a. Calcium ion pumps in the sarcoplasmic reticulum reduce the cytosolic calcium levels and tropomyosin blocks the myosin binding site on actin. b. Calcium binds to calmodulin and is quickly degraded to relieve calcium's inhibition of tropomyosin. c. Calcium is pumped out of the cell to reverse the voltage and cause myosin to degrade. d. Calcium is neutralized by an influx of negatively charged ions, which block calcium from binding to myosin.
a. Calcium ion pumps in the sarcoplasmic reticulum reduce the cytosolic calcium levels and tropomyosin blocks the myosin binding site on actin.
Cancer cells often lack normal DNA damage response and cell-cycle control mechanisms. Why does this make them more susceptible to DNA-damaging chemotherapies? a. Cancer cells might ignore the normal mechanisms that halt the cell cycle in response to damage, and subsequent division with damage leads to death. b. Cancer cells have the ability to repair the DNA properly and thus will not accumulate mutations as quickly. c. Cancer cells will arrest in the cycle and will not grow further. d. Cancer cells with activating mutations in Ras will amplify the damage through the Ras signaling pathway.
a. Cancer cells might ignore the normal mechanisms that halt the cell cycle in response to damage, and subsequent division with damage leads to death.
Which of the following statements about integrins is false? a. Integrins use adaptor proteins to interact with the microtubule cytoskeleton. b. Integrins can switch to an activated state by binding to an extracellular matrix molecule. c. Integrins can switch to an activated state by binding to an intracellular protein. d. An activated integrin molecule takes on an extended conformation.
a. Integrins use adaptor proteins to interact with the microtubule cytoskeleton.
Which is NOT a transition point where the cell cycle control system regulates progression through the cell cycle? a. S/G2 transition b. G1/S transition c. G2/M transition d. chromosome segregation
a. S/G2 transition
What accounts for the difference in the curve shapes depicting concentration of M-cyclin versus M-Cdk activity during the cell cycle? a. The M-Cdk complex is not activated until M-cyclin is bound and M-Cdk is dephosphorylated. b. The M-Cdk complex is not activated until M-cyclin is fully bound. c. The M-Cdk complex is not activated until it is dephosphorylated in mitosis. d. The M-Cdk activity levels reach their peak slowly due to the time required for synthesis of the proteins.
a. The M-Cdk complex is not activated until M-cyclin is bound and M-Cdk is dephosphorylated.
Which of the following statements about plant cell walls is true? a. The microtubule cytoskeleton directs the orientation in which cellulose is deposited in the cell wall. b. The molecular components of the cell wall are the same in all plant tissues. c. Because plant cell walls are rigid, they are not deposited until the cell has stopped growing. d. The cellulose found in cell walls is produced as a precursor molecule in the cell and delivered to the extracellular space by exocytosis.
a. The microtubule cytoskeleton directs the orientation in which cellulose is deposited in the cell wall.
Cancerous cells can accumulate mutations more quickly for all the following reasons EXCEPT a. a mutation in a cell proliferation gene. b. a mutation that causes mistakes in mitosis. c. a mutation in a DNA repair gene. d. a mutation in a gene involved in DNA replication.
a. a mutation in a cell proliferation gene.
What is an epithelium? a. a sheet of cells joined tightly together b. tissue with dense extracellular matrix and sparse cells c. a sphere of closely packed cells d. a meshwork of laminin protein
a. a sheet of cells joined tightly together
You are interested in understanding the regulation of nuclear lamina assembly. To create an in vitro system for studying this process you start with partly purified nuclear lamina subunits to which you will add back purified cellular components to drive nuclear lamina assembly. Before you start doing experiments, your instructor suggests that you consider what type of conditions would be most amenable to the assembly of the nuclear lamina from its individual subunits in vitro. Which of the following additions do you predict would be most likely the enhance the assembly of the nuclear lamina? a. addition of protein kinase inhibitors b. addition of phosphate inhibitors c. addition of a concentrated salt solution that is 10 times the concentration normally found in the nucleoplasm d. addition of ATP
a. addition of protein kinase inhibitors
Which type of junction involves a connection to the actin cytoskeleton? a. adherens junctions b. desmosomes c. tight junctions d. gap junctions
a. adherens junctions
Microtubules extend from organizing centers in the cell. Which is an example of an organizing center? a. basal body of a cilium b. centromere of a chromosome c. nuclear periphery d. vesicle membrane
a. basal body of a cilium
This figure shows how the movement of dynein causes the flagellum to bend. If instead of the normal situation, the polarity of the adjacent doublet of microtubules were to be reversed (see figure 17-24B), what do you predict would happen? a. bending would occur, except that the right microtubule doublet would moved down relative to the left one. b. the two microtubules would slide away from each other. c. bending would occur exactly as diagrammed in figure 17-24A. d. no bending would occur
a. bending would occur, except that the right microtubule doublet would moved down relative to the left one.
Which molecule is primarily responsible for providing tensile strength in the connective tissues of animals? a. collagen b. cellulose c. lignin d. intermediate filaments
a. collagen
Epithelial cells attach to a sheet of extracellular matrix composed of a. collagen and laminin. b. keratin and lamins. c. fibronectin and vimentin. d. plectin and actin.
a. collagen and laminin.
What is a function common to all epithelia? a. creation of a barrier b. secretion of hormones c. absorption of nutrients d. sensing light signals
a. creation of a barrier
Which motor protein is an ATPase, has two globular heads, moves toward the (-) end of a microtubule, and generally interacts with cargo via an adaptor protein? a. cytoplasmic dynein b. kinesin c. myosin-I d. myosin-II
a. cytoplasmic dynein
M-Cdk is suddenly activated at the end of G2 by a. dephosphorylation by Cdc25. b. phosphorylation by Wee1. c. activation of APC/C. d. destruction of cyclins.
a. dephosphorylation by Cdc25.
What drives the reassembly of the nuclear envelope? a. dephosphorylation of lamins b. destruction of cohesin c. expression of all new lamin proteins d. invagination of the ER membrane
a. dephosphorylation of lamins
A cell can crawl through a tissue because of the transmembrane __________ proteins that can bind to fibronectin outside of the cell. a. integrin b. collagen c. gap junction d. claudin
a. integrin
Which of the cytoskeletal structures are made up of protein subunits that are fibrous? a. intermediate filaments b. actin filaments c. microtubules d. None. All of the protein subunits that make up cytoskeletal structures are globular.
a. intermediate filaments
Which of these tissues has the fastest turnover rate? a. intestinal epithelium b. nerves c. bone d. blood
a. intestinal epithelium
A passenger mutation in cancer is different from a driver mutation in that it a. is not necessary for the formation of the cancerous changes. b. is sufficient to promote cancer cell growth. c. is a mutation that leads to genetic instability. d. is a mutation in an oncogene.
a. is not necessary for the formation of the cancerous changes.
Stem cells in the gut epithelium form precursor cells that differentiate as they move ___________ to the epithelial sheet, whereas precursor cells formed from the skin epidermis stem cells move ___________ to the epithelial sheet. a. parallel; perpendicular b. perpendicular; parallel c. parallel; parallel d. perpendicular; perpendicular
a. parallel; perpendicular
When a terminally differentiated cell in an adult body dies, it can typically be replaced in the body by a stock of ________. a. proliferating precursor cells. b. cells more apically located than the terminally differentiated cells. c. Wnt proteins. d. induced pluripotent cells.
a. proliferating precursor cells.
What determines the position of the cleavage furrow of the dividing cell? a. The two spindle poles send signals to the plasma membrane so that the cleavage furrow forms in the same plane as the two poles. b. The interpolar microtubules send signals to form a cleavage furrow between the poles. c. The cleavage furrow position is determined randomly. d. Astral microtubules contact the membrane and activate proteins to form a central furrow.
b. The interpolar microtubules send signals to form a cleavage furrow between the poles.
The contractile ring is composed of a. tubulin and dynein. b. actin and myosin. c. tubulin and kinesin. d. keratin fibers.
b. actin and myosin.
Which of the following conditions is likely to decrease the likelihood of skeletal muscle contraction? a. a mutation in tropomyosin that decreases its affinity for the actin filament b. addition of a drug that blocks Ca2+ binding to troponin c. an increase in the amount of ATP in the cell d. partial depolarization of the T-tubule membrane, such that the resting potential is closer to zero
b. addition of a drug that blocks Ca2+ binding to troponin
Proteoglycans in the extracellular matrix of animal tissues ________________. a. chiefly provide tensile strength. b. allow cartilage to resist compression. c. are linked to microtubules through the plasma membrane. d. are polysaccharides composed of glucose subunits.
b. allow cartilage to resist compression.
Which of the following statements about collagen is FALSE? a. the terminal procollagen domains are cleaved by protease in the extracellular space b. collagen synthase organizes the mature collagen molecules into ordered collagen fibrils c. cells can break down a collagen matrix using matrix proteases d. Collagen is synthesized as a procollagen and secreted to the outside of the cell in a secretory vesicle
b. collagen synthase organizes the mature collagen molecules into ordered collagen fibrils
At the end of M phase, cells shut down Cdk activity through which of the following mechanisms? a. mitogen-activated signaling b. deployment of Cdk inhibitors c. shutting down all gene expression d. degrading the Rb protein
b. deployment of Cdk inhibitors
Which of the following junctions binds a cell to another cell and is linked to keratin intermediate filaments? a. adherens junction b. desmosome c. hemidesmosome d. tight junction
b. desmosome
At desmosomes, cadherin molecules are connected to ________________. a. actin filaments. b. intermediate filaments. c. microtubules. d. gap junctions.
b. intermediate filaments.
A basal lamina ______________________. a. is a thin layer of connective-tissue cells and matrix underlying an epithelium. b. is a thin layer of extracellular matrix underlying an epithelium. c. is attached to the apical surface of an epithelium. d. separates epithelial cells from each other.
b. is a thin layer of extracellular matrix underlying an epithelium.
Under a microscope, how would the connective tissue of an animal generally appear? a. many densely packed cells with thin bundles extracellular matrix between them b. loosely scattered cells among large amounts of extracellular matrix c. a network of extracellular matrix fibers with no cells d. densely packed cells filled with tight fibers of collagen and keratin
b. loosely scattered cells among large amounts of extracellular matrix
Which of the following motor proteins has one head domain, moves along actin toward the plus end, and is found in all cell types? a. cytoplasmic dynein b. myosin-I c. myosin-II d. kinesin
b. myosin-I
An oncogene is different from a tumor suppressor gene in that a. mutation of the gene can contribute to cancer. b. oncogenes have mutations causing increased activity of the protein. c. oncogenes have mutations causing decreased activity of the protein. d. oncogene mutations more rarely lead to cancer.
b. oncogenes have mutations causing increased activity of the protein.
In response to DNA damage, the ___________ protein is phosphorylated and activates the transcription of a Cdk inhibitor to halt cell cycle progression. a. p21 b. p53 c. p27 d. Rb
b. p53
How does S-Cdk prevent re-replication? a. activation of helicases to denature DNA b. phosphorylation of ORC and Cdc6 c. inactivation of G1-Cdk d. degradation of DNA polymerase
b. phosphorylation of ORC and Cdc6
In which phase of mitosis does the nuclear envelope break down? a. prophase b. prometaphase c. anaphase d. metaphase
b. prometaphase
Which of the following is an important function of intermediate filaments? a. forming attachments for cells to move along a substrate b. providing tensile strength to the cell and the nucleus c. separating chromosomes during mitosis d. moving vesicles from location to location in the cell
b. providing tensile strength to the cell and the nucleus
Sister chromatid separations occurs because _________________ are destroyed by the APC/C a. kinetochores b. securins c. condesins d. cohesins
b. securins
Cohesin is cleaved by the enzyme ___________, which is held in an inactive state by ___________ until it is degraded by the APC/C complex. a. securin; separase b. separase; securin c. nuclease; securin d. separase; kinetochores
b. separase; securin
Microtubules are inherently unstable unless they are a. able to bind GTP. b. stabilized by a (+) end attachment. c. bound to kinesin. d. assembled in the nucleus.
b. stabilized by a (+) end attachment.
A major distinction between the connective tissues in an animal and other main tissue types such as epithelium, nervous tissue, or muscle is _______________. a. the ability of connective-tissue cells such as fibroblasts to change shape. b. the amount of extracellular matrix in connective tissues. c. the ability of connective tissues to withstand mechanical stresses. d. the numerous connections that connective-tissue cells make with each other.
b. the amount of extracellular matrix in connective tissues.
Which of the following is not an example of a connective tissue? a. bone b. the layer of photoreceptors in the eye c. the jellylike interior of an eye d. cartilage
b. the layer of photoreceptors in the eye
What is the function of condensins? a. to hold sister chromatids together b. to coil sister chromatids into a compact form c. to break down the nuclear envelope d. to shorten the contractile ring
b. to coil sister chromatids into a compact form
The slow rise of S cyclin levels throughout G1 phase is due to ___________, and the abrupt decrease is caused by ___________. a. phosphorylation; translation b. transcription; proteolysis c. import; export d. synthesis; mitosis
b. transcription; proteolysis
How do calcium ions stimulate contraction in nonmuscle cells and smooth muscle cells? a. Calcium ions bind to troponin and lead to a conformational change in tropomyosin that exposes the myosin binding sites on the actin filament. b. Calcium ions released into the cell promote the release of secretory vesicles that send neurotransmitters to neighboring cells to stimulate an action potential. c. Calcium ions lead to activation of a kinase that phosphorylates nonmuscle myosin to alter its conformation and enable actin binding. d. Calcium ions trigger an action potential in the cell, leading to gene expression changes that influence contraction.
c. Calcium ions lead to activation of a kinase that phosphorylates nonmuscle myosin to alter its conformation and enable actin binding.
Which of the following statements is FALSE? a. inhibiting the Cdc25 phosphatase will delay the G2/M transition b. The activating phosphatase (Cdc25) removes the phosphates from mitotic Cdk that were added by Wee1, so that M-Cdk will be active c. Cdc25 dephosphorylation of Wee1 activates the kinase, promoting the G2/M transition d. phosphorylation of mitotic Cdk by the inhibitory kinase (Wee1) make the Cdk inactive
c. Cdc25 dephosphorylation of Wee1 activates the kinase, promoting the G2/M transition
Which of the following statements is FALSE? a. Glycosaminoglycans are components of proteoglycan b. The negative charge associated with proteoglycans attracts cations, which cause water to be sucked into the extracellular matrix c. Proteoglycans are a major component of compact connective tissues but are relatively unimportant in watery tissues such as the jellylike substance in the interior of the eye d. Proteoglycans can act as filters to regulate which molecules pass through the extracellular medium
c. Proteoglycans are a major component of compact connective tissues but are relatively unimportant in watery tissues such as the jellylike substance in the interior of the eye
What accounts for the difference in the curve shapes depicting concentration of M-cyclin versus M-Cdk activity during the cell cylce? a. the M-Cdk complex is not activated until it is dephosphorylated in mitosis b. The M-Cdk complex is not activated until M-cyclin is fully bound c. The M-Cdk complex is not activated until M-cyclin is bound and M-Cdk is dephosphorylated d. the M-Cdk activity levels reach their peaks slowly due to the time required for synthesis of the proteins
c. The M-Cdk complex is not activated until M-cyclin is bound and M-Cdk is dephosphorylated
If a chromosome is attached to two microtubules from opposite poles and one of the microtubules is experimentally severed, what occurs? a. The chromosome remains aligned along the equator of the metaphase spindle. b. The remaining microtubule releases the chromosome contacts. c. The chromosome migrates quickly to the pole to which it is still attached. d. The severed microtubule immediately regenerates and reattaches.
c. The chromosome migrates quickly to the pole to which it is still attached.
How are spindle microtubules attached to chromosomes? a. The plus ends of the microtubules bind directly to DNA. b. The minus ends of the microtubules bind directly to a protein complex on DNA. c. The microtubules bind to the kinetochore complexes through a connecting protein. d. The microtubules bind to cohesion complexes on the DNA.
c. The microtubules bind to the kinetochore complexes through a connecting protein.
How do the intermediate filament proteins keratin, vimentin, and neurofilaments differ from each other? a. Their central rod domains are very different and do not all form coiled-coils. b. The dimers assemble into filaments in a completely different way. c. They are different at the head and tail domains that are exposed at the surface. d. They do not differ. All intermediate filament proteins are identical.
c. They are different at the head and tail domains that are exposed at the surface.
What is the epithelium? a. a sphere of closely packed cells b. a meshwork of laminin protein c. a sheet of cells joined tightly together d. tissue with dense extracellular matrix and sparse cells
c. a sheet of cells joined tightly together
Which of the following statements about gap junctions is FALSE? a. gap junctions can close in response to extracellular signals b. molecules up to 1000 daltons in molecular mass can move across gap junctions c. because gap junctions only allow uncharged molecules to pass through, they are not used for electrically coupling cells d. gap junctions are made of connexons
c. because gap junctions only allow uncharged molecules to pass through, they are not used for electrically coupling cells
When an action potential excites a muscle cell, where do the calcium ions come from? a. the extracellular space b. the sarcoplasmic reticulum c. both the extracellular space and the sarcoplasmic reticulum d. the calcium secretory vesicles
c. both the extracellular space and the sarcoplasmic reticulum
induced pluripotent stem (iPS) cells a. have been used to create human clones b. can differentiate into a greater variety of adult tissues than embryonic stem cells c. can be created by the expression of a set of key genes in most somatic cell types, including cells derived from adult tissues d. require a supply of donor egg cells, as is the case of embryonic stem cells
c. can be created by the expression of a set of key genes in most somatic cell types, including cells derived from adult tissues
Adherens junctions a. are found only in adult tissues b. involve fibronectin and integrin interactions c. can be used to bend epithelial sheets into tubes d. are most often found at the basal surface of cells
c. can be used to bend epithelial sheets into tubes
An adult hemopoietic stem cell found in the bone marrow ______________________. a. will occasionally produce epidermal cells when necessary. b. can produce only red blood cells. c. can undergo self-renewing divisions for the lifetime of a healthy animal. d. will express all the same transcription factors as those found in an unfertilized egg.
c. can undergo self-renewing divisions for the lifetime of a healthy animal.
Apoptosis differs from necrosis in that necrosis a. requires the reception of an extracellular signal. b. causes DNA to fragment. c. causes cells to swell and burst, whereas apoptotic cells shrink and condense. d. involves a caspase cascade.
c. causes cells to swell and burst, whereas apoptotic cells shrink and condense.
Which represents the order of these from smallest unit of organization to the largest? a. tissues < cells < organs b. organs < tissues < cells c. cells < tissues < organs d. Tissues and organs are at the same level of organization.
c. cells < tissues < organs
In response to an apoptotic stimulus, initiator caspases a. degrade executioner caspases. b. degrade procaspases. c. cleave and activate executioner caspases. d. cleave a transcription factor to active gene expression.
c. cleave and activate executioner caspases.
Which of the following molecules is not found in plants? a. cellulose b. lignin c. collagen d. pectin
c. collagen
The plasmodesmata in plants are functionally most similar to which animal cell junction? a. tight junction b. adherens junction c. gap junction d. desmosome
c. gap junction
Which of the following statement about integrins is FALSE? a. an activated integrin molecule takes on an extended conformation b. integrins can switch to an activated state by binding to an extracellular matrix molecule c. integrins use adaptor proteins to interact with the microtubule cytoskeleton d. integrins can switch to an activated state by binding to an intracellular protein
c. integrins use adaptor proteins to interact with the microtubule cytoskeleton
In terms of structure, if cytoplasmic intermediate filaments are described as ropes, nuclear lamins could be best described as a. string. b. wood. c. mesh. d. glass.
c. mesh.
A ___________ is a long structure found in abundance in the cytoplasm of a single skeletal muscle fiber, and is composed of many bundles of actin and myosin filaments that are arranged in repeating units. a. sarcomere b. contractile ring c. myofibril d. thick filament
c. myofibril
Which of the following cell types is responsible for removing matrix for renewal in bone tissue? a. osteoblasts b. fibroblasts c. osteoclasts d. epithelial
c. osteoclasts
Microtubules are made up of 13 ___________ that are linear chains of ___________. a. tubulin dimers; protofilaments b. tubulin rings; microfilaments c. protofilaments; tubulin dimers d. microfilaments; tubulin rings
c. protofilaments; tubulin dimers
The binding of ATP causes a conformational change in myosin that a. moves the myosin head one step forward on the actin filament. b. move the actin filament in a force-generating "power stroke." c. releases the myosin head from the actin filament. d. attaches the myosin head to the actin filament.
c. releases the myosin head from the actin filament.
Which of the following statements about actin is FALSE? a. actin at the cell cortex helps govern the shape of the plasma membrane b. actin filaments are nucleated at the side of existing actin filaments in lamellipodia c. the dynamic instability of actin filaments is important for cell movement d. ATP hydrolysis decreases actin filament stability
c. the dynamic instability of actin filaments is important for cell movement
Which of the following actin-binding proteins prevent polymerization of actin monomers? a. formins and ARPs b. formins and profilin c. thymosin and profilin d. thymosin and ARPs
c. thymosin and profilin
Which type of junction contributes the most to the polarization of epithelial cells? a. adherens junctions b. desmosomes c. tight junctions d. gap junctions
c. tight junctions
Taxol and colchicine are used to treat cancer because they arrest dividing cells in mitosis. What is the mechanism of action of these drugs? a. Both drugs stabilize microtubules. b. Both drugs destabilize microtubules. c. Taxol prevents polymerization of microtubules, colchicine prevents disassembly of microtubules. d. Both drugs constrain the dynamic instability of microtubules.
d. Both drugs constrain the dynamic instability of microtubules.
You create cells with version of the origin recognition complex, ORC, that cannot be phosphorylated by S-Cdk and this cannot be inactivated. Which of the following statements describes the likely consequence of this change in ORC? a. cells will enter the S phase prematurely b. ORC will be unable to bind to DNA c. DNA helicases will not be able to open up the double helix at the replication origin d. Cell will replicate some regions of the genome more than once in a cell cycle
d. Cell will replicate some regions of the genome more than once in a cell cycle
Rb is an important protein for controlling cell proliferation by blocking entry into S phase. How does it exert its effect? a. When phosphorylated by G1-Cdk, Rb binds to DNA and activates transcription. b. Signaling through mitogen-activated pathways activates Rb kinase activity. c. In its phosphorylated state, Rb is active and blocks G1-Cdk activity. d. In its unphosphorylated state, Rb is active and blocks transcriptional regulators.
d. In its unphosphorylated state, Rb is active and blocks transcriptional regulators.
Which of the following correctly matches the phase of the eukaryotic cell cycle with an event that takes place in that phase? a. S phase-cell growth b. G1 phase-DNA synthesis c. G2 phase-mitosis d. M phase-cytokinesis
d. M phase-cytokinesis
Which of the following statements about cellulose is false? a. Cellulose synthase enzyme complexes are integral membrane proteins. b. An array of microtubules guides the cellulose synthase complex as it moves in the membrane. c. The sugar monomers necessary for the synthesis of a cellulose polymer are transported across the plasma membrane. d. Microtubules are directly attached to the outside surface of the plasma membrane to form tracks that help orient the cellulose polymers.
d. Microtubules are directly attached to the outside surface of the plasma membrane to form tracks that help orient the cellulose polymers.
Which of the situations below will enhance microtubule shrinkage? a. addition of a drug that inhibits hydrolysis of the GTP tubulin dimers b. addition of a drug that increases the affinity of tubulin molecules carrying GDP for other tubulin molecules c. addition of a drug that blocks the ability of a tubulin dime to bind to γ-tubulin d. addition of a drug that inhibits GTP exchange on free tubulin dimers
d. addition of a drug that inhibits GTP exchange on free tubulin dimers
Hemidesmosomes are important for a. tubulation of epithelial sheets. b. linkages to glycosaminoglycans. c. forming the basal lamina. d. attaching epithelial cells to the extracellular matrix.
d. attaching epithelial cells to the extracellular matrix.
Which of the following about tumor suppressor genes is FALSE? a. individuals with only one functional copy of a tumor suppressor gene are more prone to cancer than individuals with two functional copies of a tumor suppressor gene b. gene amplification of a tumor suppressor gene is less dangerous than gene amplification of a proto-oncogene c. inactivation of tumor suppressor genes leads to enhanced cell survival and proliferation d. cells with one functional copy of a tumor suppressor gene will usually proliferate faster than normal cells
d. cells with one functional copy of a tumor suppressor gene will usually proliferate faster than normal cells
Mouse embryonic stem (ES) cells ______________________. a. can only be produced through therapeutic cloning. b. can give rise to all tissues and cell types in the body except germ cells. c. can be implanted in foster mothers to produce cloned cows and other animals. d. come from the inner cell mass of early embryos.
d. come from the inner cell mass of early embryos.
A cell that is terminally differentiated will a. replicate its DNA b. reenter the cell cycle only once a year c. arrest after S phase d. dismantle the cell-cycle control system
d. dismantle the cell-cycle control system
Hemopoietic stem cells in the bone marrow produce all of the following specialized cells EXCEPT a. red blood cells. b. neutrophils. c. osteoclasts. d. heart muscle cells.
d. heart muscle cells.
Which word or phrase below best describes the phase in mitosis depicted in the figure? a. prometaphase b. S-phase checkpoint c. anaphase d. metaphase
d. metaphase
Microtubules participate in the spatial polarization of nerve cells because a. microtubules are only located in the nerve cell body. b. microtubules extend through the axon with (-) ends toward the terminal and bind vesicles there. c. microtubules have no polarity. d. microtubule (-) ends originate near the cell body allowing (+) end-directed transport along the axon.
d. microtubule (-) ends originate near the cell body allowing (+) end-directed transport along the axon.
Fibroblasts organize the collagen of the extracellular matrix by ______________. a. cutting and rejoining the fibrils. b. processing procollagen into collagen. c. twisting fibrils together to make ropelike fibers. d. pulling the collagen into sheets or cables after it has been secreted.
d. pulling the collagen into sheets or cables after it has been secreted.
Which of the following descriptions is consistent with the behavior of a call that lacks protein required for checkpoint mechanism that operated in G2? a. the cell would be unable to enter the M phase b. the cell would pass through M phase more slowly than normal cells c. the cell would be unable to enter G2 d. the cell would enter the M phase under conditions when normal cells would not
d. the cell would enter the M phase under conditions when normal cells would not
Both multicellular plants and animals have _____________________. a. cells capable of locomotion. b. cells with cell walls. c. a cytoskeleton composed of actin filaments, microtubules, and intermediate filaments. d. tissues composed of multiple different cell types.
d. tissues composed of multiple different cell types.
The artificial introduction of three key __________ into an adult cell can convert the adult cell into a cell with the properties of ES cells. a. chromosomes b. viruses c. hormones d. transcription factors
d. transcription factors