Deck 19: Integrating Cells Into Tissues

Question 1

EDTA is a divalent cation chelator.Propose an explanation for how EDTA promotes the dissociation of animal cell tissue?

Answer 1

Much of cell-cell adhesion is mediated by cadherins.Cadherin interactions between cells are Ca²⁺ dependent.EDTA chelates divalent cations,including Ca²⁺,leading to dissociation of cadherin cell-cell interactions.

Question 2

A tight junction is made up of which of the following proteins?

A)tricellulin
B)occludin
C)claudin
D)all of the above

Answer 2

D

Question 3

Cellular responses to adhesion receptor signaling do NOT include:

A)cell proliferation.
B)cytoskeletal organization.
C)gene transcription.
D)all of the above

Answer 3

D

Question 4

What are the cytoskeletal proteins associated with hemidesmosomes?

Question 5

Desmosomes:

A)associate with actin filaments on the cytoplasmic side.
B)contain the transmembrane proteins desmoglein and desmocollin.
C)inhibit transfer of membrane proteins from the basolateral to the apical domain.
D)contain integrins.

Question 6

Which of the following is the term used to describe a thin,sheet-like meshwork of extracellular matrix components that can be found in epithelial cells?

A)basal lamina
B)basement membrane
C)gap junction
D)cell wall

Question 7

The collagen triple-helix domain is NOT:

A)rich in glycine.
B)an α helix.
C)rich in proline.
D)rich in hydroxyproline.

Question 8

What is the function of a gap junction?

Question 9

Syndecans are cell-surface proteoglycans that:

A)bind to collagens.
B)bind to multi-adhesive matrix proteins.
C)anchor cells to the extracellular matrix.
D)all of the above

Question 10

Basal lamina include all of the following,except:

A)type I collagen.
B)type IV collagen.
C)laminin.
D)nidogen.

Question 11

In a classic experiment,H.V.Wilson studied aggregation of mechanically dissociated individual sponge cells from two different species.He found that the cells of each species would adhere to one another but not to cells of the other species.Describe the factors involved in this species-specific aggregation.

Question 12

What is a polarized epithelial cell?

Question 13

The functions of the extracellular matrix include:

A)supporting differentiation.
B)inducing morphogenesis.
C)binding growth hormones.
D)all of the above

Question 14

Which of the following statements best describes the difference between low-affinity integrins and high-affinity integrins?

A)Many integrins can exist in two conformations: a low-affinity (bent)conformation and a high-affinity (straight)conformation.
B)Dissociation of the αβ heterodimer converts many integrins from the low-affinity to the high-affinity state.
C)Association of the αβ heterodimer converts many integrins from the low-affinity to the high-affinity state.
D)Proteolytic cleavage of the C-terminal tails of the two subunits converts many integrins from the low-affinity to the high-affinity state.

Question 15

Vertebrate gap junctions are composed of:

A)adherins.
B)collagens.
C)connexins.
D)integrins.

Question 16

Which one of the following is NOT a property of perlecan?

A)It contains laminin-like LG domains.
B)It is a proteoglycan.
C)It is only found in the basal lamina.
D)It is a glycoprotein.

Question 17

Proteoglycans are:

A)located exclusively at the cell surface.
B)located exclusively in the extracellular matrix.
C)highly positively charged.
D)glycoproteins that contain glycosaminoglycans.

Question 18

Multiadhesive matrix proteins form adhesive bridges between what components or structures?

Question 19

The major families of cell surface adhesion molecules include:

A)cadherins and selectins.
B)integrins.
C)the Ig-superfamily.
D)all of the above

Question 20

Cadherin cellular adhesion molecules promote:

A)collagen binding.
B)multiadhesive matrix protein binding.
C)cell-specific homophilic interactions.
D)all of the above

Question 21

Biological roles of proteoglycans and hyaluronan include all of the following,except:

A)maintenance of porosity for the diffusion of small molecules between cells and tissues.
B)presentation of growth factors to cells.
C)resistance to compression.
D)storage sites for extracellular energy reserves.

Question 22

As fibroblasts form a three-dimensional structure in contact with the ECM,the cells bound to ECM:

A)exhibit less mobility.
B)make the same adhesion structures as fibroblasts grown in two-dimensional culture.
C)proliferate at a faster rate.
D)de-differentiate.

Question 23

Heparan sulfate,an example of a(n)_____________,aids in the activation of ____________.

A)GAG;FGFR
B)proteoglycan;FGF
C)multi-adhesive protein;FGFR
D)integrin;cell motility

Question 24

Which of the following is NOT true regarding matrix metalloproteases?

A)Their activity depends on zinc ions.
B)They are responsible for cleaving β-catenin from E-cadherin.
C)They are inhibited by TIMPs.
D)Some of the members are called gelatinases.

Question 25

What are the three unusually abundant amino acids in collagen?

Question 26

What signal is released by endothelial cells to recruit circulating leukocytes?

A)Vesicle-sequestered P-selectins are moved to the cell surface.
B)Vesicle-sequestered αL β2 molecules are moved to the cell surface.
C)Integrins are cleaved from the plasma membrane so that the extracellular domain can bind leukocytes.
D)Secreted glycoproteins trigger leukocytes to initiate "rolling" motility.

Question 27

Dystroglycan is a large glycoprotein that binds to dystrophin in muscle cells.It is also present in other cells and can also bind to:

A)laminin.
B)the virus that causes Lassa fever.
C)the bacterium that causes leprosy.
D)all of the above

Question 28

Which extracellular matrix component is expressed in a cell-specific manner and binds to the tripeptide sequence Arg-Gly-Asp?

A)integrins
B)collagen
C)proteoglycans
D)fibronectins

Question 29

Describe the importance of extravasation and how leukocytes use this mechanism to fight infection/inflammation.

Question 30

Hydroxyproline is important in the formation of staple collagen polymers within cells.The formation of hydroxyproline requires:

A)vitamin A.
B)vitamin B.
C)vitamin C.
D)vitamin D.

Question 31

What effect might an injection of RGD peptide have on tumor cells moving through the blood/lymph system?

A)block cell attachment to new tissue and therefore prevent metastasis
B)encourage clumping of cancer cells for removal by the immune system
C)promote tumor cell binding to platelets and potentially lead to a fatal clot
D)block integrin-mediated cell cycle progression

Question 32

What is the oligomeric structure of integrins?

Question 33

 In mice engineered to overexpress the syndecan-1 gene in the hypothalamic region of the brain and other tissues,normal control of feeding by antisatiety peptides is disrupted,and the animals overeat and become obese.Other studies have shown that syndecan-3 may also be involved in the regulation of feeding behavior.Given the following information,which of these outcomes might you expect in experimentally manipulated mice?
Hypothalmic expression of syndecan-3 is increased by fasting.
Syndecan-3 knockout mice are resistant to diet-induced obesity.
Heparinase can cleave syndecan-3 to release heparin sulfate GAG chains that may suppress the activity of antisatiety peptides and feeding behavior.

A)Overexpression of heparinase in mice with normal levels of syndecan-3 would result in resistance to diet-induced obesity.
B) In mice with normal levels of syndecan-3,fasting followed by free access to a high-fat diet would lead to resistance to diet-induced obesity.
C)Lack of heparinase in mice with normal levels of syndecan-3 would result in animals that overeat and become obese.
D)Overexpression of heparinase in syndecan-3 knockout mice would reverse the resistance to diet-induced obesity.
E)There are two plausible hypotheses: 1)Overexpression of heparinase in mice with normal levels of syndecan-3 would result in resistance to diet-induced obesity;and 2)lack of heparinase in mice with normal levels of syndecan-3 would result in animals that overeat and become obese.

Question 34

NCAMs,a group of cell-adhesion proteins belonging to the Ig superfamily:

A)are more heavily sialylated in embryonic tissues than in adult tissues.
B)bind to proteoglycans.
C)mediate Ca²⁺-dependent cell-to-cell binding.
D)all of the above

Question 35

What is the role of Ca²⁺ in NCAM-mediated homophilic cell-cell adhesion?

Question 36

How are multiple forms of fibronectin generated?

Question 37

Polymerization of collagen into large collagen fibers occurs:

A)in the endoplasmic reticulum.
B)in the Golgi complex.
C)in secretory vesicles.
D)extracellularly.

Question 38

What kinds of polymerized structures do collagen types form?

Question 39

People with a defect in the synthesis of the integrin β2 subunit exhibit reduced:

A)leukocyte attachment.
B)leukocyte rolling.
C)endothelial cell activation.
D)extravasation.

Question 40

Which of the following best describes the structure of integrins?

A)Integrins cluster in cis until coming into contact with another cell,where a trans network forms.
B)Integrins are homodimers of subunits expressed in a cell-type specific manner,
C)A single integrin subunit forms heterophilic interactions with fibronectin and laminin.
D)Integrins are heterodimers composed of α and β subunits.

Question 41

How are cellulose fibrils laid down in parallel arrays?

Question 42

Pectins and hyaluronic acid are both:

A)secreted by animal cells.
B)very negatively charged.
C)proteins.
D)intracellular substances.

Question 43

What is the function of plasmodesmata in plants?

Question 44

Which of these is NOT a component of plant cell walls?

A)collagen
B)pectin
C)cellulose
D)hemicellulose