Question # 1Select thesinglebest answer to the numbered
question.Each of the following is true of both cadherins and
integrins EXCEPTXA.both are transmembrane glycoproteins
XB.both can associate with the actin cytoskeleton
XC.both represent gene families
D.both may be found in zonula adherens junctions
XE.both are involved in cell adhesion
You answered:CX
Explanations:
A.This is a true statement and hence an incorrect answer for
this EXCEPT question.
B.This is a true statement and hence an incorrect answer for
this EXCEPT question. Integrins associate with the actin
cytoskeleton at focal adhesions (sites of cell-ECM adhesion.
Cadherins associate with the actin cytoskeleton in adherens
junctions between epithelial cells.
C.This is a true statement and hence an incorrect answer for
this EXCEPT question.
D.Only cadherins are found in zonula adherens junctions. Hence
this is an incorrect statement and the CORRECT answer to this
EXCEPT question.
E.This is a true statement and hence an incorrect answer for
this EXCEPT question. Cadherins are involved in desmosomes and
adherens junctions. Integrins are involved in focal adhesions and
hemidesmosomes.
This question is not currently linked to the learning objective
database.
Question problem?
Question # 2Select thesinglebest answer to the numbered
question.Which of the following BEST describes the adhesive
interaction required for neutrophil (leukocyte) "rolling" as
depicted in the sequence labeled "1" in the diagram? XA.I-CAM
molecules on the neutrophil cell surface bind to integrins on the
endothelial cell surface
B.Selectins on the endothelial cell surface bind to specific
carbohydrates on the neutrophil cell surface
XC.Integrins on the neutrophil cell surface bind to selectins on
the endothelial cell surface
XD.Selectins on the neutrophil cell surface bind to specific
carbohydrates on the endothelial cell surface
You answered:B
Explanations:
A.Sequence 2 (not sequence 1) in the diagram is due to an
interaction of I-CAM on the endothelial surface (not the neutrophil
surface) with an integrin on the neutrophil surface (not the
endothelial cell surface). For these reasons, this is an incorrect
answer.
B.This is a correct description of the receptor interactions
responsible for events shown in "1" in the diagram and hence the
correct answer.
C.Integrins do not bind to selectins. The selectins on the
endothelial surface bind to carbohydrate groups on the neutrophil
cell surface. Therefore, this is an incorrect answer.
D.This is backwards from what actually happens during the events
shown in "1" in the diagram. The selectins on the endothelial cell
surface (not the neutrophil surface) interact with carbohydrate
groups on the neutrophil surface (not the endothelial cell
surface). Hence, this is an incorrect answer.
This question is not currently linked to the learning objective
database.
Question problem?
Question # 3Select thesinglebest answer to the numbered
question.Cell adhesion to the extracellular matrix (ECM)
glycoprotein fibronectin can involveXA.the binding of select
immunoglobin superfamily members (IgSF) to the Arg-Gly-Asp (RGD)
sequence in fibronectin.
XB.Ca+2independent binding of selectins to the Arg-Gly-Asp (RGD)
sequence in fibronectin.
XC.Ca+2dependent binding of selectins to the Arg-Gly-Asp (RGD)
sequence in fibronectin.
D.the binding of integrins to the Arg-Gly-Asp (RGD) sequence in
fibronectin.
XE.Ca+2dependent binding of selectins to specific carbohydrate
groups on the fibronectin glycoprotein.
You answered:D
Explanations:
A.IgSF molecules are involved in cell-cell adhesion and do not
bind ECM molecules. Thus, this is an incorrect answer.
B.Selectins contain Ca+2-dependent lectin domains that bind to
specific carbohydrates expressed at the surfaces of other cells in
order to mediate cell-cell adhesive interactions. Selectins do not
bind to fibronectin. Thus, this is an incorrect answer.
C.Selectins contain Ca+2-dependent lectin domains that bind to
specific carbohydrates expressed at the surfaces of other cells in
order to mediate cell-cell adhesive interactions. Selectins do not
bind to fibronectin. Thus, this is an incorrect answer.
D.The RGD amino acid sequence in fibronectin, and other proteins
such as fibrinogen, is the primary cell adhesion site recognized by
select integrins at the cell surface. Thus, this is the correct
answer.
E.Selectins contain Ca+2-dependent lectin domains that bind to
specific carbohydrates expressed at the surfaces of other cells in
order to mediate cell-cell adhesive interactions. Selectins do not
mediate the adhesion of cells to the fibronectin glycoprotein.
Thus, this is an incorrect answer.
This question is not currently linked to the learning objective
database.
Question problem?
Question # 4Select thesinglebest answer to the numbered
question.Cell adhesion to the extracellular matrix (ECM)
glycoprotein fibronectin can involve which of the following
scenarios?XA.The binding of select immunoglobin superfamily members
(IgSF) to the Arg-Gly-Asp (RGD) sequence in fibronectin
XB.Ca+2independent binding of selectins to the Arg-Gly-Asp (RGD)
sequence in fibronectin
XC.Ca+2dependent binding of selectins to the Arg-Gly-Asp (RGD)
sequence in fibronectin
D.The binding of integrins to the Arg-Gly-Asp (RGD) sequence in
fibronectin
XE.Ca+2dependent binding of selectins to specific carbohydrate
groups on the fibronectin glycoprotein
You answered:D
Explanations:
A.IgSF molecules are involved in cell-cell adhesion and do not
bind ECM molecules. Thus, this is an incorrect answer.
B.Selectins contain Ca+2-dependent lectin domains that bind to
specific carbohydrates expressed at the surfaces of other cells in
order to mediate cell-cell adhesive interactions. Selectins do not
bind to fibronectin. Thus, this is an incorrect answer.
C.Selectins contain Ca+2-dependent lectin domains that bind to
specific carbohydrates expressed at the surfaces of other cells in
order to mediate cell-cell adhesive interactions. Selectins do not
bind to fibronectin. Thus, this is an incorrect answer.
D.The RGD amino acid sequence in fibronectin, and other proteins
such as fibrinogen, is the primary cell adhesion site recognized by
select integrins at the cell surface. Thus, this is the correct
answer.
E.Selectins contain Ca+2-dependent lectin domains that bind to
specific carbohydrates expressed at the surfaces of other cells in
order to mediate cell-cell adhesive interactions. Selectins do not
mediate the adhesion of cells to the fibronectin glycoprotein.
Thus, this is an incorrect answer.
The question is mapped to following learning objectives for
school year 2013-2014:1. (ID: 19833) Explain the functional
importance of the Arg-Gly-Asp (RGD) site in fibronectin and
fibrinogen.
Question problem?
Question # 5Select thesinglebest answer to the numbered
question.Which of the following statements about desmosomes is
true?XA.They are the portion of the junctional complex that is
closest to the lumen
XB.They encircle the entire cell forming an adhesion belt
XC.They function as a diffusion barrier
D.They are associated with intermediate filaments
XE.Connexin membrane proteins contribute to their structure
You answered:D
Default Explanation:No explanation provided.
This question is not currently linked to the learning objective
database.
Question problem?
Question # 6Select thesinglebest answer to the numbered
question.What is a characteristic of Glanzmann's
Thrombasthenia?XA.It is caused by mutations in selectin genes
XB.There is an absence of pus following bacterial infection
C.Platelet aggregation is defective
XD.Platelet cadherins fail to bind to the actin cytoskeleton
upon activation
XE."Activated" platelets bind fibrinogen
You answered:C
Explanations:
A.Glanzmanns Thrombasthenia is a bleeding disorder involving
defects in platelet aggregation. Selectins are not involved in
platelet aggregation upon platelet activation. Thus, this is an
incorrect answer.
B.Absence of pus (which is mostly composed of neutrophils)
indicates la ikely deficiency in leukocyte function as, for
example, in the case of leukocyte adhesion deficiency (LAD).
Glanzmanns is a bleeding disorder involving defects in platelets,
not leukocytes. Thus, this answer is not correct.
C.This answer is correct because failure of platelet aggregation
is a feature of Glanzmanns Thrombasthenia. The inability of
platelets to bind fibrinogen, become activated and to aggregate is
due to defects in platelet integrins.
D.Cadherins are not involved in platelet aggregation and,
therefore, cannot account for the defects in platelet adhesion
observed in Glanzmanns patients. Thus, this is an incorrect
answer.
E.Normal activated platelets bind fibrinogen but those obtained
from Glanzmanns patients have defective integrins and do not bind
fibrinogen. Fibrinogen binding is required for platelet
aggregation. Thus, this answer is incorrect.
The question is mapped to following learning objectives for
school year 2013-2014:1. (ID: 19834) Describe the role of integrin
IIb/3 receptor in normal platelet aggregation and the defects
underlying Glanzmanns Thrombasthenia.
Question problem?
Question # 7Select thesinglebest answer to the numbered
question.Each of the following is true ofbothcadherins and
integrins EXCEPTXA.both are transmembrane glycoproteins
XB.both can associate with the actin cytoskeleton
XC.both represent gene families
XD.both may associate with intermediate filaments
E.both are involved in cell-extracellular matrix (cell-ECM)
adhesion
You answered:E
Explanations:
A.This is a true statement thus an incorrect answer for this
EXCEPT question. Integrins function as heterodimers of distinct
protein subunits, both of which are transmembrane glycoproteins.
Cadherins are also transmembrane glycoproteins.
B.This is a true statement thus an incorrect answer for this
EXCEPT question. Integrins associate with the actin cytoskeleton at
focal adhesions (sites of cell-ECM adhesion) on migrating.
Cadherins also associate with actin cytoskeleton at the class of
cell-cell adhesive contacts that includes adherens junctions (found
in some epithelia and in cardiac muscle).
C.This is a true statement thus an incorrect answer for this
EXCEPT question. There are multiple cadherin and integrin genes
expressed by cells and tissues throughout the body.
D.This is a true statement thus an incorrect answer for this
EXCEPT question. Intermediate filaments are associated with
integrins in hemidesmosomes and with cadherins in desmosomes. Note
that this does not contradict the statement in answer B.
E.Cadherins are not involved in cell-ECM adhesion; they are
always involved in cell-cell adhesion. Integrins are involved in
cell-ECM adhesion and in some cases, can mediate cell-cell
adhesion. Because cadherins are not involved in cell-ECM adhesion
this statement is incorrect, thus is the CORRECT answer for this
EXCEPT question.
This question is not currently linked to the learning objective
database.
Question problem?
Your Score: 86 % 32) A type of adhesive junction that is
associated with the connection between an epithelial cell and the
basal lamella is theA) hemidesmosome.B) desmosome.C) gap
junction.D) plasmodesmata.E) focal contact.
34) In the extracellular matrix of animal cells, collagen and
elastin fibers are embedded with this matrix.A) glycoaminoglycansB)
proteoglycansC) pectinsD) ligninsE) both choices A and B
36) The organ where you would most likely expect to find actin
microfilaments continuous with adherens junctions is theA) liver.B)
stomach.C) kidney.D) brain.E) heart.1) A person is genotypically
blood type A. However, this individual also does not produce the
lipid to which N-acetylgalactosamine is added, so the lipid is
therefore not expressed on the surface of erythrocytes. This
situation is known as the Bombay phenotype. When tested, this
person will appear to be blood typeA) A.B) B.C) AB.D) O.
2) Polarized cells are characterized byA) random orientation
within a tissue.B) a polar flagellum.C) random orientation within
an organ.D) distinct apical and basolateral sides.E) both choices B
and D
3) Which of the following cell junctions are associated with the
proper alignment of intestinal epithelial cells?A) gap junctionsB)
adhesive junctionsC) tight junctionsD) desmosomesE) all of the
above
4) In animal cells, the extracellular matrix plays important
roles in all of the following processes exceptA) cell division.B)
motility.C) DNA replication.D) differentiation.E) adhesion.
5) A newly defined autoimmune disorder has resulted in an immune
response against Type V collagen fibers. As a result, the most
likely organ to be targeted in this response would be theA) skin.B)
heart.C) lungs.D) stomach.E) tongue.
6) Which of the following statements is true regarding cell-cell
adhesion?A) Adhesion is coordinated with many cellular processes
except cell survival.B) Adhesion molecules include plakoglobulin,
which cements two cells together.C) Adherens junctions are
exclusive to plant cells.D) Adhesive junctions are characterized by
the attachment of long molecules of hyaluronate.E) Adhesive
junctions are dynamic in response to cellular signals.
7) Which of the following is not associated with adhesive
junctions?A) desmosomesB) hemidesmosomesC) plaquesD) connexinE)
cadherins
8) Which of the following is mismatched?A)
IgSF[emdash]chondroitinB) cadherins?calcium ionsC)
selectins?leukocytesD) cadherins?embryonic developmentE)
lectins?carbohydrates
9) Which of the following is false with regard to the
extracellular matrix?A) These structures are external to the cell
membrane, but are still an integral component of cell function.B)
Extracellular matrices are only found in association with
eukaryotic cells.C) Extracellular matrices play a role in
determining the shape of a cell.D) Bone and cartilage are examples
of cells that have specialized extracellular matrices associated
with their function.E) Extracellular matrices play a role in
determining the mechanical properties of tissues and organs.
10) Which of the following activities is not associated with
cadherins?A) segregation of cells to specific tissuesB)
paracellular transportC) embryonic developmentD) establishment of
synaptic connectionsE) loss of activity associated with cancer
11) Which of the following components is not associated with the
primary cell wall?A) cellulose microfibrilsB) hemicellulosesC)
pectinsD) glycoproteinsE) lignins
12) Which of the following is the correct order for the
synthesis of the plant cell wall, from the outermost layer to the
innermost layer?A) middle lamella; primary cell wall; secondary
cell wall; plasma membraneB) primary cell wall; middle lamella;
secondary cell wall; plasma membraneC) plasma membrane; secondary
cell wall; primary cell wall; middle lamellaD) middle lamella;
secondary cell wall; primary cell wall; middle lamellaE) primary
cell wall; secondary cell wall; plasma membrane; middle lamella
13) You discover a dog suffering from a strange disorder that is
due to an autoimmune response against its own cells. Upon further
investigation, you find that the cells of various tissues are
loosely arranged and do not have characteristic shapes and that the
animal is prone to hemorrhage as the result of poor blood clotting.
Based on these results, the target of the autoimmune response could
beA) fibronectins.B) laminins.C) extensins.D) pectins.E)
desmotubules.
14) The function of integrin-linked kinase during integrin-based
signaling isA) integrin activation.B) anchorage-dependent growth.C)
scaffolding protein.D) cell movement.E) anchorage-independent
growth.
15) A patient is rushed to the emergency room and immediately
needs a blood transfusion. The patient is found to have only anti-A
antibodies in circulation. The blood type of this individual must
beA) A.B) B.C) AB.D) O.
16) A person with neither anti-A nor anti-B antibodies in
circulation has which of blood type?A) AB) BC) ABD) O
17) In which of the following organs would you expect to find
adhesive junctions in humans?A) heart muscleB) skin epitheliumC)
uterusD) both choices A and BE) choices A, B, and C
18) Which of the following is correctly paired with regard to
similarity in function?A) adhesive junctions-tight junctionsB)
desmotubule-gap junctionC) tight junctions-gap junctionsD)
plaques-plasmodesmataE) connexons-desmosomes
19) Paracellular transport is associated with which of the
following?A) adherens junctionsB) integrinsC) desmosomesD) tight
junctionsE) hemidesmosomes
20) You are investigating a clinical disorder in one of your
patients. You discover that the patient has an autoimmune disease
that targets and destroys fibroblasts. This disorder would most
likely affectA) fiber production by the cells, as occurs with blood
clotting.B) annulus formation.C) hyluronate production in the
joints.D) collagen production.E) all of the above
21) Of the proteoglycans associated with the extracellular
matrix in vertebrates, which of the following is associated with
the lubrication of joints?A) chondroitin sulfateB) glucuronateC)
hyaluronateD) keratan sulfateE) mucoproteins
22) The protein invasin is associated withA) Yersinia
psuedotuberculosis.B) the construction of an integrin network in
bacteria.C) plasmodemata.D) tight-junction ridge formation.E)
lubrication of joints.
23) You are investigating cell localization by targeting the
carbohydrates associated with various cell types. Based on this
molecule's ability to bind various carbohydrates, which of the
following would help determine which carbohydrates are found on the
cell surface?A) cadherinsB) proteoglycansC) pectinsD) connexinsE)
lectins
24) Which of the following is mismatched with regard to similar
excellular structures in plant and animal cells?A)
elastins-extensinsB) extracellular matrix-cell wallC)
collagens-celluloseD) proteoglycans-hemicellulosesE)
fibronectins-pectins
25) Some observations have suggested to researchers that
substances associated with the extracellular matrix may be involved
in cell migration. This has been observed with the cell marker CD44
on the surface of cancer cells and their ability to be separate
from one another and to easily metastasize to other regions of the
body. This is most likely due to the interaction of CD44 andA)
chondrotin sulfate.B) ICAMs.C) hyaluronate.D) fibronectins.E)
elastin.
26) Which of the following is not associated with the basal
lamina?A) serves as a structural supportB) allows for movement of
some small moleculesC) can influence cell migrations in certain
areas of the bodyD) contains collagen type IV, proteoglycans,
laminins, and entactinE) contains the most abundant supply of
fibronectins.
27) An elderly patient presents with blistering of the skin. You
suspect an autoimmune disorder. If your suspicions are correct, the
patient's serum should contain antibodies reactive toA) talin.B)
vinculin.C) a-actinin.D) BPAG.E) actin.
28) In performing research, you treat frog zygotes with
antibodies that bind E-cadherin. As a result, you expectA) the
cells to become exclusively muscle tissue.B) the cells to be
loosely associated and abort development.C) the cells to be loosely
associated and develop into a novel strain of frog.D) the cells to
divide uncontrollably.E) no change with regard to development.
29) Collagens are associated with which of the following types
of cellular junctions?A) gap junctionsB) tight junctionsC)
plasmodesmataD) adhesive junctionsE) none of the above
30) Focal contact is associated with which of the following type
of cellular junction?A) adhesive junctionB) gap junctionC)
plasmodesmataD) tight junctionsE) all of the above
31) The type of cellular junction prominent in the stomach and
kidney is theA) plasmodesmata.B) gap junction.C) adhesive
junction.D) tight junction.E) laminin junction.
32) A type of adhesive junction that is associated with the
connection between an epithelial cell and the basal lamella is
theA) hemidesmosome.B) desmosome.C) gap junction.D)
plasmodesmata.E) focal contact.
33) The insoluble layer of aromatic alcohols that are primarily
found in woody tissues are theA) annulus.B) cadherins.C)
proteoglycans.D) lignins.E) pectins.
34) In the extracellular matrix of animal cells, collagen and
elastin fibers are embedded with this matrix.A) glycoaminoglycansB)
proteoglycansC) pectinsD) ligninsE) both choices A and B
35) The molecule of the extracellular matrix of animal cells
that is associated with joint lubrication and friction reduction
isA) glycosaminoglycan.B) proteoglycan.C) hyaluronate.D) pectin.E)
fibronectin.
36) The organ where you would most likely expect to find actin
microfilaments continuous with adherens junctions is theA) liver.B)
stomach.C) kidney.D) brain.E) heart.
37) The plant cell wall network is comprised of all of the
following exceptA) hyaluronate.B) cellulose.C) extensin.D)
hemicellulose.E) pectin.
38) The primary polysaccharides associated with the plant cell
wall are theA) hemicelluloses.B) extensins.C) fibronectins.D)
pectins.E) both choices A and D
39) A collection of fibrous intracellular attachment proteins is
called a(n)A) annulus.B) connexon.C) plaque.D) tonofilament.E) both
choices C and D
40) The autoimmune response to desmosomes or desmosomal
components (not hemidesmosomes) leads to a blistering skin disease
known asA) pemphigus.B) Ehlers?Danos syndrome.C) syndecan.D)
junctional epidermolysis bullosa.E)listerosistriosis.
1). Which of the following techniques has recently aided the
study of receptor proteins?a). protein purificationb). monoclonal
antibodiesc). isolation of cell signal moleculesd). all of
theseAnswer:b
2). Which of the following describes autocrine signaling?a).
Signal molecules released by cells diffuse through the
extracellular fluid to other cells.b). Signal molecules enter the
organism's circulatory system and travel throughout the body.c).
Signal molecules are released from a cell and bind to receptors on
its own plasma membrane.d). Signal molecules are released into a
narrow space between cells called a synapse.Answer:c
3). Intracellular receptors usually binda). water-soluble
signals.b). large molecules that act as signals.c). signals on the
cell surface.d). lipid-soluble signals.Answer:d
4). Which of the following isnota type of cell surface
receptor?a). chemically gated ion channelsb). intracellular
receptorsc). enzymic receptorsd). G-protein-linked
receptorsAnswer:b
5). Which of the following is not a second messenger?a).
adenylyl cyclaseb). cyclic adenosine monophosphatec). calcium
ionsd). cAMPAnswer:a
6). The amplification of a cellular signal requires all but
which of the following?a). a second messengerb). DNAc). a signal
moleculed). a cascade of protein kinasesAnswer:b
7). MHC proteins area). molecules that determine a person's
blood type.b). large molecules that pass through the membrane many
times.c). identity markers present on the surface of an
individual's cells.d). different for each type of tissue in the
body.Answer:c
8). Sheets of cells are formed from which type of cell
junctions?a). tight junctionsb). anchoring junctionsc).
communication junctionsd). none of theseAnswer:a
9). Cadherin can be found in which of the following?a). tight
junctionsb). anchoring junctionsc). communication junctionsd).
adherens junctionsAnswer:b
10). Plasmodesmata are a type ofa). gap junction.b). anchoring
junction.c). communicating junction.d). tight junction.Answer:c
Test Your Visual Understanding
1). Match the following labels with the appropriate structures
in the figure, and explain where each type of junction is
found.adherens junctiondesmosomegap junctionhemidesmosometight
junction
Answer:1). Tight junction with #1, Adherens junction with #2,
Desmosomes with #3, Gap junction with #4 and Hemidesmosome with
#51--Tight junctionTight junctions hold cells together in a sheet,
restricting the movement of substances between the cells. Tight
junctions are found in cells that line the digestive
tract.2--Adherens junctionAdherens junctions are anchoring
junctions that use integrin to hold cells together by anchoring to
the cells' actin networks. Adherens junctions, as other anchoring
junctions are found in tissues that are subject to mechanical
stress such as muscle and epithelium.3--DesmosomesDesmosomes are
anchoring junctions that use cadherin to hold cells together by
anchoring to the cells' actin networks, or for more stable
cell-to-cell connections by anchoring to the cells' intermediate
fibers. Desmosomes, as other anchoring junctions are found in
tissues that are subject to mechanical stress such as muscle and
epithelium.4--Gap junctionGap junctions are communicating junctions
that use protein channels called connexons to create passageways
between cells. When the connexons of two adjacent cells are lined
up, a direct connection between the cytoplasms of the two cells is
made. Small molecules and ions can pass freely between the cells.
Gap junctions are found in animal
cells.5--HemidesmosomeHemidesmosomes are anchoring junctions that
use cadherin to hold cells to an extracellular matrix.
Hemidesmosomes are found in epithelial cells, holding them to a
basement membrane.
Apply Your Knowledge1). In paracrine signaling, the signal
molecule is destroyed by enzymes in 6 milliseconds. The diffusion
rate of the signal through the extracellular fluid is 2 nanometer/1
millisecond. How long will the signal last in the extracellular
fluid, and what is the farthest distance a target cell can be from
the releasing cell to be affected by the signal?Answer:Enzymes
breakdown the signal molecule in 6 milliseconds so the signal can
only last for 6 milliseconds in the extracellular fluid. Therefore,
the signal has only 6 milliseconds to travel to its target cell. If
the signal can travel 2 nanometers/millisecond then:2 nanometers x
6 milliseconds = 12 nanometersThe farthest distance a target cell
can be from the releasing cell is 12 nanometers.
2). At first glance, the signaling systems that involve cell
surface receptors may appear rather complex and indirect, with
their use of G proteins, second messengers, and often multiple
stages of enzymes. What are the advantages of such seemingly
complex response systems?Answer:There are several advantages to
response system that is organized in multiple levels. The first is
obviously the ability to amplify the signal. With the multiple
stages of enzymes, a small amount of a signal is all that is needed
to get the response going. This allows for a very high level of
sensitivity.
Another advantage is the ability of the cell to use the same
"machinery" for different signals--not having to produce new
cascade machines to elicit the same response or a related response.
If two signals produce the same response, two different G proteins
could activate the same adenylyl cyclase and activate the same
cascade. Similarly, the same second messenger, for example cAMP
could be used in different cascade responses, offering a certain
redundancy to the system.
3).Shigella flexneriis one of several species of bacteria that
cause shigellosis, or bacillary dysentery. Recent evidence has
shown thatS. flexnericannot spread between the epithelial cells of
the intestines without the expression of cadherin by those cells.
Why do you suppose it cannot?Answer:Shigella flexneriinvades one
cell, multiplies and then spreads to contiguous epithelial cells.
Cells that are expressing cadherin are closely adhering to their
neighboring cells, which makes it easier forShigella flexnerito
spread.
1. Which of the following type of organism is always
multicellular? A. animals only B. plants only C. archae only D.
prokaryotes only E. both animals and plants
Bloom's Level: RememberSection: 10.01Topic: Cells2. Which of the
following is most TRUE about multicellular organisms when compared
with unicellular organisms? A. Multicellular organisms carry out
specialized functions, while unicellular organisms do not. B.
Multicellular organisms can reproduce themselves, while unicellular
organisms cannot. C. Multicellular organisms can digest more
complex molecules than unicellular organisms. D. Multicellular
organisms tend to have larger genomes than unicellular organisms.
E. Multicellular organisms show development while unicellular
organisms do not.
Bloom's Level: UnderstandSection: 10.01Topic: Cells
3. The bones and cartilage in animals serve the same function as
________ in plants? A. leaves B. phloem C. capillaries D. wood E.
xylem
Bloom's Level: UnderstandSection: 10.01Topic: Cells4. In
animals, which of the following structures is largely composed of
extracellular matrix? A. kidney B. intestine C. eye D. cartilage E.
muscle
Bloom's Level: RememberSection: 10.01Topic: Cells5. Which of the
following is NOT a function of the extracellular matrix? A.
provides strength B. provides structural support C. provides
organization of cells throughout the organism D. provides an
important source of energy for the organism E. cell signaling
Bloom's Level: RememberSection: 10.01Topic: Cells
6. Which of the following ECM molecules provides tensile
strength? A. fibronectin B. collagen C. laminin D. elastin E.
proteoglycan
Bloom's Level: RememberSection: 10.01Topic: Cells7. Which of the
following statements about the ECM is most CORRECT? A. It is
composed of living cells. B. Its components are produced by
specialized cells and transported throughout the body and deposited
around the cell. C. It is a source of protein for cells. D. It
protects cells from infectious agents. E. Its components are
produced and secreted by the cell.
Bloom's Level: UnderstandSection: 10.01Topic: Cells8. The major
macromolecules of the ECM are polysaccharides and A. lipids. B.
fat. C. proteins. D. nucleotides. E. amino acids.
Bloom's Level: RememberSection: 10.01Topic: Cells
9. Which of the following statements about collagen is
INCORRECT? A. There can be numerous types of collagen in
multicellular organisms B. It is produced from polymers of amino
acids. C. It tends to promote the "sticky" characteristics of the
ECM. D. Its breakdown is a contributing characteristic of wrinkling
during aging. E. It is a major component of the ECM for cartilage
and bone.
Bloom's Level: UnderstandSection: 10.01Topic: Cells10. Which
collagen type is most rigid and is very abundant in bones and
tendons? A. Type I B. Type II C. Type III D. Type IV E. Type V
Bloom's Level: RememberSection: 10.01Topic: Cells11. Which ECM
molecule provides structure while allowing certain tissues to
expand and contract (e.g., lungs during breathing, intestine during
digestion)? A. collagen B. elastin C. fibronectin D. laminin E.
glycosaminoglycans
Bloom's Level: ApplySection: 10.01Topic: Cells
12. This polysaccharide is an important ECM component for the
exoskeleton of many insects and shellfish. A. proteoglycan B.
glycosaminoglycans C. collagen D. chitin E. laminin
Bloom's Level: RememberSection: 10.01Topic: Cells13. Which of
the following statements about proteoglycans is TRUE? A.
Proteoglycans are composed of collagen. B. Proteoglycans are
composed of polysaccharides called glycosaminoglycans. C.
Proteoglycans provide resistance to compression. D. Proteoglycans
are both composed of collagen and provide resistance to
compression. E. Proteoglycans are both composed of polysaccharides
called glycosaminoglycans and provide resistance to
compression.
Bloom's Level: UnderstandSection: 10.01Topic: Cells14. Which of
the following ECM molecules is probably the most abundant organic
molecule on Earth? A. proteoglycans B. collagen C. chitin D.
cellulose E. laminins
Bloom's Level: UnderstandSection: 10.01Topic: Cells
15. Which of the following statements about the cell wall is
FALSE? A. The cell wall constitutes the ECM of plants. B. The cell
wall is composed predominantly of proteins. C. The cell wall
provides protection, rigidity, and shape to plant cells. D. The
cell wall is composed of two distinct layers. E. The cell wall is
composed mainly of carbohydrates.
Bloom's Level: RememberSection: 10.01Topic: Cells16. All of the
following statements about cellulose are true EXCEPT: A. Cellulose
is composed of fibers of carbohydrates. B. Cellulose is an
important source of plant fiber for our diet. C. Cellulose is the
primary molecule found in wood. D. Cellulose is one of the most
abundant organic molecules on Earth. E. Certain animals like
ourselves can easily digest cellulose and use it as a source of
energy.
Bloom's Level: UnderstandSection: 10.01Topic: Cells17. Which of
the following forms a protective layer outside of the plasma
membrane of the plant cell? A. cell wall B. cellulose C. chitin D.
pectin E. proteoglycans
Bloom's Level: RememberFigure: 10.05Section: 10.01Topic:
Cells
18. Which of the following is NOT a function of cellular
junctions? A. Cellular junctions hold adjacent cells together. B.
Cellular junctions prevent leakage of materials between cell
layers. C. Cellular junctions permit the direct exchange of small
molecules between cytosol of adjacent cells. D. Cellular junctions
bond cells to their ECM. E. Cellular junctions promote the motility
of adjacent cells.
Bloom's Level: RememberSection: 10.02Topic: Cells19. All of the
following represent anchoring junctions EXCEPT A. tight junctions.
B. focal adhesions. C. hemidesmosomes. D. desmosomes. E. adherens
junctions.
Bloom's Level: RememberFigure: 10.07Section: 10.02Topic:
Cells20. These act as rivets anchoring adjacent cells together at
spots throughout the cell. A. adherens junctions B. desmosomes C.
hemidesmosomes D. focal adhesions E. fibronectin
Bloom's Level: RememberFigure: 10.07Section: 10.02Topic:
Cells
21. These anchorage junctions interact with intermediate
filaments and anchor cells to the extracellular matrix. A. adherens
junctions B. desmosomes C. hemidesmosomes D. focal adhesions E.
fibronectin
Bloom's Level: RememberFigure: 10.07Section: 10.02Topic:
Cells22. Which of the following statements comparing hemidesmosomes
with desmosomes is TRUE? A. Hemidesmosomes are anchorage junctions
but desmosomes are not. B. Hemidesmosomes interact with actin
filaments while desmosomes interact with intermediate filaments. C.
Both hemidesmosomes and desmosomes associate with integrin, but not
cadherin molecules. D. Hemidesmosomes anchor cells to the ECM while
desmosomes anchor cells to other cells. E. Hemidesmosomes are found
in plant cells while desmosomes are found in animal cells.
Bloom's Level: UnderstandSection: 10.02Topic: Cells23. Which of
the following is NOT a component of focal adhesions? A. cadherins
B. integrins C. actin filaments D. linker protein E.
fibronectin/collagen
Bloom's Level: RememberSection: 10.02Topic: Cells
24. All of the following are components of the adherens junction
complex EXCEPT A. cadherins. B. Ca2+. C. intermediate filaments. D.
linker protein. E. actin filaments.
Bloom's Level: RememberSection: 10.02Topic: Cells25. Which of
the following cell junctions would function the LEAST like glue? A.
gap junctions B. adherens junctions C. focal adhesions D.
hemidesmosomes E. desmosomes
Bloom's Level: UnderstandSection: 10.02Topic: Cells26. This
forms a seal that prevents the movement of substances between
cells, for instance from the intestinal lumen into the blood. A.
gap junctions B. tight junctions C. desmosomes D. hemidesmosomes E.
focal adhesions
Bloom's Level: RememberFigure: 10.09Section: 10.02Topic:
Cells
27. Gap junctions are to animal cells as ________ are to plant
cells? A. middle lamella B. hemidesmosomes C. plasmodesmata D.
primary cell walls E. tight junctions
Bloom's Level: UnderstandFigure: 10.11Figure: 10.14Section:
10.02Topic: Cells28. What structure cements plant cells together?
A. middle lamella B. hemidesmosomes C. plasmodesmata D. primary
cell walls E. adherens junctions
Bloom's Level: RememberFigure: 10.13Section: 10.02Topic:
Cells29. One can inject dyes of different sizes into a liver cell
and determine those molecules that can readily pass through gap
junctions. What sized molecules can pass through gap junctions? A.
1,000 Daltons, but 1,500 Daltons, but 5,000 Daltons, but 10,000
Daltons
Bloom's Level: RememberSection: 10.02Topic: Cells
30. Which of the cell adhesion molecules is critical to
transducing changes in the ECM to a change in the cell? A.
connexins B. cadherins C. integrins D. fibronectins E. claudins
Bloom's Level: RememberFigure: 10.08Section: 10.02Topic:
Cells31. Which molecules are essential components of tight
junctions? A. cadherins and connexins B. cadherins and integrins C.
claudins and integrins D. cadherins and claudins E. connexins and
claudins
Bloom's Level: RememberSection: 10.02Topic: Cells32. Which of
the following junctions are important for cell signaling? A.
adherins junctions B. gap junctions C. plasmodesmata D. desmosomes
E. All of the choices are correct.
Bloom's Level: UnderstandSection: 10.02Topic: Cells
33. A group of cells having similar structure and function is
called a(n) A. tissue. B. organ. C. organ system. D. organism. E.
population.
Bloom's Level: RememberSection: 10.03Topic: Cells34. The heart
is a(n) ________ composed mainly of ________ tissue? A. tissue,
cardiac B. organ, muscle C. tissue, connective D. organ, connective
E. organ, epithelial
Bloom's Level: UnderstandSection: 10.03Topic: Cells35. Which of
the following basic cell processes is NOT required for creating a
tissue? A. cell division and differentiation B. cell connections C.
cell morphology D. cell death E. cell migration
Bloom's Level: RememberSection: 10.03Topic: Cells
36. This type of tissue is rich in extracellular matrix and
includes tendon and cartilage. A. muscle B. connective C.
epithelial D. nervous E. hepatic
Bloom's Level: RememberSection: 10.03Topic: Cells37. Which of
the following tissue type covers or forms the lining of all
internal and external body surfaces? A. muscle B. connective C.
epithelial D. nervous E. hepatic
Bloom's Level: RememberSection: 10.03Topic: Cells38. The
epithelial tissue of animal cells is most similar to the ________
of plant cells? A. xylem B. vascular C. dermal D. ground E.
phloem
Bloom's Level: UnderstandSection: 10.03Topic: Cells
39. Which type of tissue constitutes most of the wood of a tree
trunk? A. dermal tissue B. parenchyma tissue C. collenchyma tissue
D. sclerenchyma tissue E. vascular tissue
Bloom's Level: ApplySection: 10.03Topic: Cells40. Which of the
following is TRUE of cork? A. It represents the major dermal tissue
in bark. B. It helps transport nutrients and fluid. C. It serves a
protective function D. It both represents the major dermal tissue
in bark and helps transport nutrients and fluid. E. It both
represents the major dermal tissue in bark and serves a protective
function.
Bloom's Level: UnderstandSection: 10.03Topic: Cells
True / False Questions41. Cells can sense changes in the
environment through alterations in the extracellular matrix.
TRUE
Bloom's Level: UnderstandSection: 10.01Topic: Cells
42. Wrinkling observed with aging is do to low production of the
extracellular matrix molecule, fibronectin. FALSE
Bloom's Level: RememberSection: 10.01Topic: Cells43. Blood
vessels that can expand and contract are largely composed of
collagen as a structural extracellular matrix protein. FALSE
Bloom's Level: RememberSection: 10.01Topic: Cells44.
Glycosaminoglycans and proteoglycans resist compression and are
found in large abundance in joints of the body. TRUE
Bloom's Level: RememberSection: 10.01Topic: Cells45. Cellulose
from the cell wall is a primary energy store for plants. FALSE
46. Rivets hold steel structures together much in the same way
as tight junctions hold cells together. FALSE47. Integrin is a
membrane protein that integrates changes in the ECM to alterations
in movement or behavior of the cell. TRUE48. Unlike animals, plants
lack a cell junction where small molecules can move from one cell
to another cell. FALSE
49. The heart, skeletal muscles, and blood vessels all share a
common feature in that they are composed of muscle tissue. TRUE
Bloom's Level: UnderstandSection: 10.03Topic: Cells50. The most
prominent tissue type present in plants is the dermis.
FALSEPhosphorylation cascades involving a series of protein kinases
are useful for cellular signal transduction because Athey always
lead to the same cellular response.B.they amplify the original
signal manyfold.Cthe number of molecules used is small and
fixed.D.they are species specific.E.they counter the harmful
effects of phosphatases.BBinding of a signaling molecule to which
type of receptor leads directly to a change in the distribution of
ions on opposite sides of the membrane?A.. intracellular receptorB.
G protein-coupled receptorC. receptor tyrosine kinaseD.
phosphorylated receptor tyrosine kinase dimerE. ligand-gated ion
channelEThe activation of receptor tyrosine kinases is
characterized byA. GTP hydrolysis.B. channel protein shape
change.C. dimerization and IP3 binding.D. dimerization and
phosphorylation.E. a phosphorylation cascade.DLipid-soluble
signaling molecules, such as testosterone, cross the membranes of
all cells but affect only target cells becauseA. only target cells
retain the appropriate DNA segments.B. intracellular receptors are
present only in target cells.C. only target cells possess the
cytosolic enzymes that transduce the testosterone.D. only in target
cells is testosterone able to initiate the phosphorylation cascade
leading to activated transcription factor.E. most cells lack the Y
chromosome required.BConsider this pathway: epinephrine- (G
protein-coupled receptor)- protein adenylyl cyclase- cAMP. Identify
the second messenger.A. adenylyl cyclaseB. G protein-coupled
receptorC. cAMPD. GTPE. G proteinCApoptosis involves all but which
of the following?A. lysis of the cellB. digestion of cellular
contents by scavenger cellsC. cell-signaling pathwaysD.
fragmentation of the DNAE. activation of cellular enzymesAWhich
observation suggested to Sutherland the involvement of a second
messenger in epinephrine's effect on liver cells?A. Receptor
studies indicated that epinephrine was a ligand.B. Glycogen
breakdown was observed only when epinephrine was administered to
intact cells.C. Enzymatic activity was proportional to the amount
of calcium added to a cell-free extract.D. Epinephrine was known to
have different effects on different types of cells.E. Glycogen
breakdown was observed when epinephrine and glycogen phosphorylase
were combined.BProtein phosphorylation is commonly involved with
all of the following exceptA. enzyme activation.B. activation of
protein kinase molecules.C. activation of G protein-coupled
receptors.D. regulation of transcription by extracellular signaling
molecules.E. activation of receptor tyrosine kinases.CSelect the
statement that correctly distinguishes between relay proteins and
second messengers in signal transduction pathways.A. Relay proteins
are the "first messengers," the extracellular signaling molecules
that bind to the membrane receptor. The signal transduction
pathways are then formed by the second messengers, which are the
relay molecules that respond to the first messengers.B. Signal
transduction pathways are multistep pathways in which relay
proteins and second messengers alternate.C. Signal transduction
pathways are multistep pathways that include relay proteins and
small, nonprotein, water-soluble molecules or ions called second
messengers.CWhich statement correctly distinguishes the roles of
protein kinases and protein phosphatases in signal transduction
pathways?A. Protein kinases activate enzymes by phosphorylating or
adding phosphate groups to them. Protein phosphatases
dephosphorylate or remove phosphate groups from enzymes, including
protein kinases.B. Protein kinases are involved in signal
transduction in unicellular eukaryotes such as yeast. Protein
phosphatases are involved in signal transduction in multicellular
eukaryotes.C. Protein kinases are more critical than protein
phosphatases to signal transduction enzymes.ACyclic GMP, or cGMP,
acts as a signaling molecule whose effects include relaxation of
smooth muscle cells in artery walls. In the penis, this signaling
pathway and the resulting dilation of blood vessels leads to an
erection. Select the correct statement about the effect of Viagra
on this signaling pathway.A. Viagra increases the rate of
hydrolysis of cGMP to GMP.B. Viagra inhibits the hydrolysis of GMP
to GMP.C. Viagra prevents the formation of cGMP.BThe cholera
bacterium Vibrio cholerae produces an enzyme toxin that chemically
modifies a G protein involved in regulating salt and water
secretion in intestinal cells. Stuck in its active form, the
modified G protein stimulates the production of a high
concentration of cAMP, which causes the intestinal cells to secrete
large amounts of salts into the intestines, with water following by
osmosis. An infected person quickly develops profuse diarrhea and
if left untreated can soon die from the loss of water and salts.
What is the basic effect of the cholera toxin?A.The basic effect of
the cholera toxin is loss of specificity of the response of
intestinal cells to a signaling molecule.B. The basic effect of the
cholera toxin is premature termination of a signaling pathway.C.
The basic effect of the cholera toxin is signal
amplification.CSelect all that apply.What are the functions of
signal transduction pathways?A. Signal transduction pathways
amplify the effect of a signal molecule.B. Signal transduction
pathways allow different types of cells to respond differently to
the same signal molecule.C. Signal transduction pathways convert a
signal on a cell's surface to a specific cellular
response.ABCPhosphorylation cascades involving a series of protein
kinases are useful for cellular signal transduction becauseA. they
counter the harmful effects of phosphatases.B. they amplify the
original signal manyfold.C. they always lead to the same cellular
response.D. they are species specific.E. the number of molecules
used is small and fixed.BWhich of the following provides molecular
evidence that signal transduction pathways evolved early in the
history of life?A. Receptor molecules have been identified in
preparations of fossilized organisms billions of years old.B.
Simple forms of life, such as prokaryotic cells, utilize cell
signaling.C. The pathways in primitive organisms, such as bacteria,
are short, whereas those in advanced forms, such as mammals, are
long.D. Cell signaling is observed in organisms that do not utilize
sexual reproduction.E. The molecular details of cell signaling are
quite similar in organisms whose last common ancestor was a billion
years ago.EWhich of the following is a substance that acts at a
long distance from the site at which it is secreted?A. synaptic
signalB. paracrine signalC. hormoneD. neurotransmitterE. local
regulatorCWhat is most likely to happen to an animal's target cells
that lack receptors for local regulators?A. Hormones would not be
able to interact with target cells.B. They could divide but never
reach full size.C. They might compensate by receiving nutrients via
a factor.D. They could develop normally in response to
neurotransmitters instead.E. They might not be able to multiply in
response to growth factors from nearby cells.EWhich of the
following is characterized by a cell releasing a signal molecule
into the environment, followed by a number of cells in the
immediate vicinity responding?A. endocrine signalingB. synaptic
signalingC. autocrine signalingD. hormonal signalingE. paracrine
signalingEIn the formation of biofilms, such as those forming on
unbrushed teeth, cell signaling serves which function?A. digestion
of unwanted parasite populationsB. aggregation of bacteria that can
cause cavitiesC. secretion of substances that inhibit foreign
bacteriaD. secretion of apoptotic signalsE. formation of mating
complexesBIn which of the following ways do plant hormones differ
from hormones in animals?A. Plant hormones interact primarily with
intracellular receptors.B. Plant hormones may travel in air or
through vascular systems.C. Animal hormones are primarily for
mating and embryonic development.D. Plant hormones are synthesized
from two or more distinct molecules.E. Animal hormones are found in
much greater concentration.BWhen a neuron responds to a particular
neurotransmitter by opening gated ion channels, the
neurotransmitter is serving as which part of the signal pathway?A.
transducerB. endocrine moleculeC. receptorD. signal moleculeE.
relay moleculeDThe following question is based on the figure
below:Which of the following types of signaling is represented in
the figure?A. synapticB. hormonalC. paracrineD. autocrineE. long
distanceAThe following question is based on the figure below:In the
figure, the dots in the space between the two structures represent
which of the following?A. hormonesB. receptor moleculesC. signal
transducersD. pheromonesE. neurotransmittersEIn yeast signal
transduction, a yeast cellA. produces signal molecules that change
the cell itself, allowing it to interact with another cell.B. must
physically and directly interact with another yeast cell.C.
secretes molecules that result in responses by other yeast cells.D.
produces response molecules that diffuse to other yeast cells.E.
mates with another cell, after which the new cells secrete hybrid
signals.CTo what does the term "ligand" refer in cell biology?A.
the target cell of a signal moleculeB. the change in shape that
occurs when a signaling molecule binds to its receptorC. any small
molecule that can bind in a specific manner to a larger oneD. the
bond that forms between a signaling molecule and its receptorE. a
molecule that can occupy a receptor site while not activating the
receptorCDioxin, produced as a by-product of various industrial
chemical processes, is suspected of contributing to the development
of cancer and birth defects in animals and humans. It apparently
acts by entering cells by simple diffusion and binding to proteins
in the cytoplasm, then altering the pattern of gene expression.
Which of the following are likely to be the cytoplasmic proteins to
which dioxin binds?A. growth factor receptorsB. enhancersC. DNA
polymerasesD. nucleosomesE. transcription factorsEWhat is the
function of tyrosine-kinase receptors?A. enzymatic degrading of GTP
to GDPB. enzymatic phosphorylation of tyrosine in the receptor
proteinC. enzymatic hydrolyzing of the signaling molecule shortly
after its arrivalD. allowing specific ions to enter the cell after
ligand bindingE. binding to nonpolar signaling molecules such as
nitric oxide or the steroid hormonesBWhich of the following is true
of transcription factors?A. They initiate the epinephrine response
in animal cells.B. They transcribe ATP into cAMP.C. They regulate
the synthesis of lipids in the cytoplasm.D. They control gene
expression.E. They regulate the synthesis of DNA in response to a
signal.DOne of the major categories of receptors in the plasma
membrane reacts by forming dimers, adding phosphate groups, and
then activating relay proteins. Which type does this?A.
ligand-gated ion channelsB. receptor tyrosine kinasesC. G
protein-coupled receptorsD. steroid receptorsBUse this description
to answer the following question.A major group of G protein-coupled
receptors contains seven transmembrane helices. The amino end of
the protein lies at the exterior of the plasma membrane. Loops of
amino acids connect the helices either at the exterior face or on
the cytosol face of the membrane. The loop on the cytosol side
between helices 5 and 6 is usually substantially longer than the
others.Where would you expect to find the carboxyl end?A. between
the membrane layersB. at the exterior surfaceC. at the cytosol
surfaceD. connected with the loop at H5 and H6CUse this description
to answer the following question.A major group of G protein-coupled
receptors contains seven transmembrane helices. The amino end of
the protein lies at the exterior of the plasma membrane. Loops of
amino acids connect the helices either at the exterior face or on
the cytosol face of the membrane. The loop on the cytosol side
between helices 5 and 6 is usually substantially longer than the
others.The coupled G protein most likely interacts with this
receptorA. along the exterior margin.B. along the interior
margin.C. at the loop between H5 and H6.D. at the NH3 end.E. at the
COO- end.CTestosterone functions inside a cell byA. acting as a
signal receptor that activates tyrosine kinases.B. coordinating a
phosphorylation cascade that increases spermatogenesis.C. acting as
a steroid signal receptor that activates ion channel proteins.D.
binding with a receptor protein that enters the nucleus and
activates specific genes.E. becoming a second messenger that
inhibits nitric oxide.DIf an animal cell suddenly lost the ability
to produce GTP, what might happen to its signaling system?A. It
could activate only the epinephrine system.B. It would not be able
to activate and inactivate the G protein on the cytoplasmic side of
the plasma membrane.C. It would be able to carry out reception and
transduction but would not be able to respond to a signal.D. It
would use ATP instead of GTP to activate and inactivate the G
protein on the cytoplasmic side of the plasma membrane.E. It would
employ a transduction pathway directly from an external
messenger.BWhen protein membrane receptors are activated, what
usually happens?A. The receptors open and close in response to
protein signals.B. A change occurs on only one membrane surface:
exterior or interior.C. The receptor preferentially binds with
lipid or glycolipid signal molecules.D. A change occurs in
intracellular ion concentration.E. The receptor changes
conformation after binding with signal polypeptides.EParticular
receptor tyrosine kinases (RTKs) that promote excessive cell
division are found at high levels on various cancer cells. A
protein, Herceptin, has been found to bind to an RTK known as HER2.
HER2 is sometimes excessive in cancer cells. This information can
now be utilized in breast cancer treatment if which of the
following is true?A. If the patient's cancer cells have excessive
levels of HER2.B. If HER2, administered by injection, causes cell
division.C. If the patient has RTKs only in cancer cells.D. If
Herceptin is found in the breast lymph nodes of the patient.E. If
the patient's genome codes for the HER2 receptor.AWhich of the
following is true of steroid receptors?A. The receptor may be
inside the nuclear membrane.B. The receptor molecules are free to
move in and out of most organelles.C. The receptor molecules are
themselves lipids or glycolipids.D. The unbound steroid receptors
are quickly recycled by lysosomes.E. The concentration of steroid
receptors must be relatively high in most cells.AWhich of the
following are among the most common second messengers?A. kinase and
phosphate groupsB. G proteins and GTPC. kinase and phosphataseD.
GTP and GDPE. calcium ion and cAMPEWhich of the following sequences
is correct?A. binding of a signaling molecule to its receptor G
protein activation adenylyl cyclase activation cAMP production
protein phosphorylationB. diffusion of a signaling molecule across
the plasma membrane binding of the signaling molecule to its
receptor movement of the signaling molecule-receptor complex into
the nucleus transcriptionC. binding of a growth factor to its
receptor phosphorylation cascade activation of transcription factor
transcriptionD. binding of a signaling molecule to its receptor G
protein activation phospholipase C activation IP3 production
increase in cytoplasmic calcium concentrationE. All of the choices
are correct.EWhich of the following is the best explanation for the
inability of a specific animal cell to reduce the Ca2+
concentration in its cytosol compared with the extracellular
fluid?A. loss of transcription factorsB. blockage of the synaptic
signalC. low oxygen concentration around the cellD. insufficient
ATP levels in the cytoplasmE. low levels of protein kinase in the
cellDAn inhibitor of phosphodiesterase activity would have which of
the following effects?A. prolong the effect of epinephrine by
maintaining elevated cAMP levels in the cytoplasmB. decrease the
amount of cAMP in the cytoplasmC. block the response of
epinephrineD. block the activation of G proteins in response to
epinephrine binding to its receptorE. block the activation of
protein kinase AAAdenylyl cyclase has the opposite effect of which
of the following?A. GTPaseB. phosphodiesteraseC. protein
phosphataseD. protein kinaseE. phosphorylaseBCaffeine is an
inhibitor of phosphodiesterase. Therefore, the cells of a person
who has recently consumed coffee would have increased levels ofA.
GTP.B. phosphorylated proteins.C. cAMP.D. adenylyl cyclase.E.
activated G proteins.CIf a pharmaceutical company wished to design
a drug to maintain low blood sugar levels, one approach might be to
design a compoundA. that increases phosphorylase activity.B. to
block G protein activity in liver cells.C. that activates
epinephrine receptors.D.that increases cAMP production in liver
cells.E. that keeps sugar molecules from crossing the plasma
membrane of liver cells.BIf a pharmaceutical company wished to
design a drug to maintain low blood sugar levels, one approach
might be to design a compoundA. that increases phosphodiesterase
activity.B. to stimulate G protein activity in liver cells.C. that
mimics epinephrine and can bind to the epinephrine receptor.D. that
stimulates cAMP production in liver cells.E. that does any of the
above.AAn inhibitor of which of the following could be used to
block the release of calcium from the endoplasmic reticulum?A.
adenylyl cyclaseB. tyrosine kinasesC. phospholipase CD.
serine/threonine kinasesE. phosphodiesteraseCWhich of the following
statements is true of signal molecules?A. When signal molecules
first bind to receptor tyrosine kinases, the receptors
phosphorylate a number of nearby molecules.B. In most cases, signal
molecules interact with the cell at the plasma membrane and then
enter the cell and eventually the nucleus.C. In response to some G
protein-mediated signals, a special type of lipid molecule
associated with the plasma membrane is cleaved to form IP3 and
calcium.D. Toxins such as those that cause botulism and cholera
interfere with the ability of activated G proteins to hydrolyze GTP
to GDP, resulting in phosphodiesterase activity in the absence of
an appropriate signal molecule.E. Protein kinase A activation is
one possible result of signal molecules binding to G
protein-coupled receptors.EWhich of the following is a correct
association?A. phosphorylase activity and the catabolism of
glucoseB. kinase activity and the addition of a tyrosineC. adenylyl
cyclase activity and the conversion of cAMP to AMPD.
phosphodiesterase activity and the removal of phosphate groupsE.
GTPase activity and hydrolysis of GTP to GDPEWhich of the following
amino acids are most frequently phosphorylated by protein kinases
in the cytoplasm during signal transduction?A. glycine and
histidineB. tyrosinesC. serine and threonineD. glycine and glutamic
acidE. Any of the 20 amino acids are equally phosphorylated.cThe
function of phosphatases in signal transduction is best described
as toA. inactivate protein kinases and turn off the signal
transduction.B. amplify the second messengers such as cAMP.C.
prevent a protein kinase from being reused when there is another
extracellular signal.D. move the phosphate group of the
transduction pathway to the next molecule of a series.E. amplify
the transduction signal so it affects multiple transducers.AWhat
explains the increased concentration of in the ER?A. Calcium levels
in the blood or other body fluids are extremely low.B. Calcium
concentration is kept low in the cytoplasm because of its high
usage level.C. Calcium cannot enter the plasma membrane through ion
channels.D. Calcium ions are actively imported from the cytoplasm
into the ER.E. The CA+ ions are recycled from other molecules in
the ER.DThe toxin of Vibrio cholerae causes profuse diarrhea
because itA. modifies a G protein involved in regulating salt and
water secretion.B. modifies calmodulin and activates a cascade of
protein kinases.C. signals IP3 to act as a second messenger for the
release of calcium.D. binds with adenylyl cyclase and triggers the
formation of cAMP.E. decreases the cytosolic concentration of
calcium ions, making the cells hypotonic.AWhich of the following
would be inhibited by a drug that specifically blocks the addition
of phosphate groups to proteins?A. G protein-coupled receptor
bindingB. ligand-gated ion channel signalingC. receptor tyrosine
kinase activityD. adenylyl cyclase activityE phosphatase
activityCViagra causes dilation of blood vessels and increased
blood flow to the penis, facilitating erection. Viagra acts by
inhibitingA. the hydrolysis of cGMP to GMP.B. the removal of GMP
from the cell.C. the phosphorylation of GDP.D. the
dephosphorylation of cGMP.E. the hydrolysis of GTP to GDP.AIn
general, a signal transmitted via phosphorylation of a series of
proteinsA. allows target cells to change their shape and therefore
their activity.B. requires binding of a hormone to a cytosol
receptor.C. requires phosphorylase activity.D. brings a
conformational change to each protein.E. cannot occur in yeasts
because they lack protein phosphatases.DWhich of the following most
likely would be an immediate result of growth factor binding to its
receptor?A. phosphorylase activityB. protein kinase activityC.
protein phosphatase activityD. adenylyl cyclase activityE. GTPase
activityBIn which of the following ways could signal transduction
most probably be explored in research to treat cancer?A. increase
in the concentration of phosphodiesterases in order to produce more
AMPB. alteration of protein kinases in cell cycle regulation in
order to slow cancer growthC. removal of serine/threonine phosphate
acceptors from transduction pathways in colon pre-cancerous
growthsD. expansion of the role of transduction inhibitors in the
cells before they give rise to cancerE. increase in calcium ion
uptake into the cytoplasm in order to modulate the effects of
environmental carcinogensBSutherland discovered that the signaling
molecule epinephrine:A. elevates cytosolic concentrations of cyclic
AMP.B. interacts directly with glycogen phosphorylase.C. causes
lower blood glucose by binding to liver cells.D. brings about a
decrease in levels of cAMP as a result of bypassing the plasma
membrane.E. interacts with insulin inside muscle cells.AFor the
greatest advantage of multiple steps in a transduction pathway
is:A. Each individual step can remove excess phosphate groups from
the cytoplasm.B. Having multiple steps provides for greater
possible amplification of a signal.C. Each step can be activated by
several G proteins simultaneously.D. Many of the steps can be used
in multiple pathways.E. Having multiple steps in a pathway requires
the least amount of ATP.BWhy are there often so many steps between
the original signal event and the cell's response?A. Long, highly
specific pathways minimize the possibility that a relay molecule
accidentally could activate a pathway leading to a secondary
response.B. The accumulation of genetic mutations over time has
added redundant steps to the pathway.C. Each transduction is a
checkpoint.D. Lengthy pathways provide the opportunity for the
initial pathway molecules to recycle back to inactive forms should
additional signaling molecules be present.E. Each step in a cascade
produces a large number of activated products, causing signal
amplification as the cascade progresses.EWhy can a signaling
molecule cause different responses in different cells?A. Different
cells possess different enzymes, which modify the signaling
molecule into different molecules after it has arrived.B. Different
cells have membrane receptors that bind to different sides of the
signaling molecule.C. The transduction process is unique to each
cell type; to respond to a signal, different cells require only a
similar membrane receptor.D. The transduction pathway in cells has
a variable length.E. All of the above are correct.CA drug designed
to inhibit the response of cells to testosterone would almost
certainly result in which of the following?A. a decrease in G
protein activityB. an increase in receptor tyrosine kinase
activityC. an increase in cytosolic calcium concentrationD. a
decrease in transcriptional activity of certain genesE. lower
cytoplasmic levels of cAMPDAt puberty, an adolescent female body
changes in both structure and function of several organ systems,
primarily under the influence of changing concentrations of
estrogens and other steroid hormones. How can one hormone, such as
estrogen, mediate so many effects?A. Estrogen is produced in very
large concentration and therefore diffuses widely.B. Estrogen is
kept away from the surface of any cells not able to bind it at the
surface.C. Estrogen has specific receptors inside several cell
types, but each cell responds in the same way to its binding.D.
Estrogen binds to specific receptors inside many kinds of cells,
each of which have different responses to its binding.E. The
subcomponents of estrogen, when metabolized, can influence cell
response.DWhat are scaffolding proteins?A. microtubular protein
arrays that allow lipid-soluble hormones to get from the cell
membrane to the nuclear poresB. ladderlike proteins that allow
receptor-ligand complexes to climb through cells from one position
to anotherC. large molecules to which several relay proteins attach
to facilitate cascade effectsD. relay proteins that orient
receptors and their ligands in appropriate directions to facilitate
their complexingE. proteins that can reach into the nucleus of a
cell to affect transcriptionCGTPase activity is important in the
regulation of signal transduction because itA. phosphorylates
protein kinases.B. converts cGMP to GTP.C. hydrolyzes GTP to GDP
thus shutting down the pathway.D. decreases the amount of G protein
in the membrane.E. increases the available concentration of
phosphate.CWhat is apoptosis?A. a way to stimulate transcriptionB.
a type of second messengerC. a type of membrane receptorD.
controlled cell suicideE. a metabolic step in blood clottingDWhy
has C. elegans proven to be a useful model for understanding
apoptosis?A. The animal has as many genes as complex organisms, but
finding those responsible is easier than in a more complex
organism.B. While the organism ages, its cells die progressively
until the whole organism is dead.C. All of its genes are constantly
being expressed so all of its proteins are available from each
cell.D. The nematode undergoes a fixed and easy-to-visualize number
of apoptotic events during its normal development.E. This plant has
a long-studied aging mechanism that has made understanding its
death just a last stage.DWhy is apoptosis potentially threatening
to the healthy "neighbors" of a dying cell?A. Released cellular
energy would interfere with the neighbors' energy budget.B.
Neighboring cells would activate immunological responses.C. Cell
death would usually spread from one cell to the next via paracrine
signals.D. Lysosomal enzymes exiting the dying cell would damage
surrounding cells.E. Bits of membrane from the dying cell could
merge with neighbors and bring in foreign receptors.DIn C. elegans,
ced-9 prevents apoptosis in a normal cell in which of the following
ways?A. Ced-9 remains inactive until it is signaled by ced-3 and
other caspases.B. Ced-9 cleaves to produce ced-3 and ced-4.C. It
prevents the caspase activity of ced-3 and ced-4.D. Ced-9 prevents
blebbing by its action on the cell membrane.E. Ced-9 enters the
nucleus and activates apoptotic genes.CWhich of the following
describes the events of apoptosis?A. The cell's DNA and organelles
become fragmented, the cell dies, and it is phagocytized.B. The
cell dies, and the presence of its fragmented contents stimulates
nearby cells to divide.C. The cell's DNA and organelles become
fragmented, the cell shrinks and forms blebs, and the cell's parts
are packaged in vesicles that are digested by specialized cells.D.
The cell's nucleus and organelles are lysed, and the cell enlarges
and bursts.E. The cell dies, it is lysed, its organelles are
phagocytized, and its contents are recycled.CIf an adult person has
a faulty version of the human analog to ced-4 of the nematode,
which of the following is most likely to result?A. excess skin
lossB. activation of a developmental pathway found in the worm but
not in humansC. formation of molecular pores in the mitochondrial
outer membraneD. neurodegenerationE. a form of cancer in which
there is insufficient apoptosisEIn research on aging (both cellular
aging and organismal aging), it has been found that aged cells do
not progress through the cell cycle as they had previously. Which
of the following would provide evidence that this is related to
cell signaling?A. cAMP levels change very frequently.B. Their lower
hormone concentrations elicit a lesser response.C. ATP production
decreases.D. Enzymatic activity declines.E. Growth factor ligands
do not bind as efficiently to receptors.