Question 1 Which of the following statements best describes the difference betwe
ID: 39225 • Letter: Q
Question
Question 1
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 ?? heterodimer converts many integrins from the low-affinity to the high-affinity state.
C.
Association of the ?? 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 2
The collagen triple-helix domain is not:
A.
rich in glycine.
B.
rich in proline.
C.
an ? helix.
D.
rich in hydroxyproline.
Question 3
Vertebrate gap junctions are composed of:
A.
adherins.
B.
collagens.
C.
connexins.
D.
integrins.
Question 4
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 5
Basal lamina include all of the following except:
A.
type I collagen.
B.
type IV collagen.
C.
laminin.
D.
nidogen.
Question 6
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 7
NCAMs:
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 8
Proteoglycans are:
A.
located exclusively at the cell surface.
B.
located exclusively in the extracellular matrix.
C.
glycoproteins that contain glycosaminoglycans.
D.
highly positively charged.
Question 9
Which of the following is false regarding the matrix metalloproteases?
A.
Their activity depends on zinc ions.
B.
They are responsible for cleaving ?-catenin from E-cadherin.
C.
They are inhibited by TIMPs.
D.
Some of the members are called gelatinases.
Question 10
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.
A.
Many integrins can exist in two conformations: a low-affinity (bent) conformation and a high-affinity (straight) conformation.
B.
Dissociation of the ?? heterodimer converts many integrins from the low-affinity to the high-affinity state.
C.
Association of the ?? 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.
Explanation / Answer
1. A. Many integrins can exist in two conformations: a low-affinity (bent) conformation and a high-affinity (straight) conformation.
2. C. alpha helix
3. C. connexins
4. A. Integrins
5. A. Type I collagen
6. D. Storage sites for extracellular energy reserves
7. D. All of the above
8. C. glycoproteins that contain glycosaminoglycans.
9. All of the statements are true.
10. B. contain the transmembrane proteins desmoglein and desmocollin.
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