1
Q
- Which of the following is not a reason why collagen fibrils form extracellulary rather than intracellulary during the biosynthesis and transport of collagen from the endoplasmic reticulum through the Golgi apparatus to the cell surface
a. Type 1 procollagen cannot form the triple helical oligomers that are the core structure of any collagen oligomer
b. Type 1 procollagen contains hydroxylated proline and lysine residues that prevent polypeptide chain oligomerization within the cell
c. Procollagen must be soluble and small enough to fit within the intracellular transport machinery
d. Type 1 procollagen synthesized in cells contains nonhelical segments at each end of the polychain that limit their ability to oligomerize into collagen fibrils
A
a. Type 1 procollagen cannot form the triple helical oligomers that are the core structure of any collagen oligomer
2
Q
- A major function of tight junctions is to
a. Create a strong adherence between cells
b. Promote the intermixing of proteins between the apical and basolateral surfaces of cells
c. Sort cells on the basis of adhesion during cell migration in embryos
d. Seal the space between adjacent cells to provide, for example, a barrier to sugar diffusion across an epithelial cell layer
A
d. Seal the space between adjacent cells to provide, for example, a barrier to sugar diffusion across an epithelial cell layer
3
Q
- In hemidesmosomes, integrins are indirectly linked to
a. Lamin-rich intermediate filaments within the nucleus
b. Microtubules
c. Actin microfilaments
d. Cytoplasmic intermediate filaments
A
d. Cytoplasmic intermediate filaments
4
Q
- Homophilic interactions between cells involve interactions between
a. Adhesion molecules of different molecular classes
b. Between integrins and ICAMs
c. Cadherins and -catenin
d. Adhesion molecules of the same molecular class
A
d. Adhesion molecules of the same molecular class
5
Q
- The major function of adhesion proteins such as fibronectin is to
a. Link collagen, proteoglycans, and cells containing integrins
b. Support communication between adjacent cells
c. Link epithelial cell layers
d. Seal cell layers at tight function
A
a. Link collagen, proteoglycans, and cells containing integrins
6
Q
- ____, although structurally different from gap junctions in animal cell tissues, may be thought of as the functional equivalent of gap junctions in plants
a. hemidesmosomes
b. desmosomes
c. plasmadesmata
d. adherens junctions
A
c. plasmadesmata
7
Q
- the cell-cell interactions mediated by the selectins, integrins, and most members of the Ig superfamily are ___ interactions in which the cytoskeletons of adjacent cells are not linked to one another
a. nonspecific
b. stable
c. physiologically unimportant
d. transient
A
d. transient
8
Q
- proteins of the ___ family link transmembrane proteins of the tight junctions to actin
a. catenin
b. plakin
c. zonula occludens
d. plectin
A
c. zonula occludens
9
Q
- cellulose, chitin, and hyaluronan are all deposited extracellulary by
a. ABC transporters
b. Transmembrane enzyme complexes
c. Exocytosis
d. Secretion
A
b. Transmembrane enzyme complexes
10
Q
- Which of the following statements about collagen is false?
a. It is the most abundant protein in animal tissues
b. It forms a double helix, with two collagen molecules wrapped around one another in a ropelike structure
c. It contains an amino acid called hydroxyproline
d. It is a secreted protein
A
b. It forms a double helix, with two collagen molecules wrapped around one another in a ropelike structure
11
Q
- The major transmembrane proteins in tight junctions include all of the following except
a. Thrombospondin
b. Occludin
c. Claudin
d. JAM
A
a. Thrombospondin
12
Q
- The junctions between animal cells that allow the free passage of molecules smaller than approximately 1000 daltons are called
a. Hemidesmosomes
b. Gap junctions
c. Tight junctions
d. Plasmodesmata
A
b. Gap junctions
13
Q
- The basic structural polysaccharide of fungal cell walls, crab shells, and insect exoskeletons is
a. Chitin
b. Collagen
c. Hemicellulose
d. Cellulose
A
a. Chitin
14
Q
- Primary plant cells walls are cross-linked by
a. Lignin
b. Turgin
c. Pectin
d. Hemicellulose
A
c. Pectin
15
Q
- Adherens junctions and desmosomes may be distinguished from each other on the basis of
a. The linkage of cadherins either to actin filaments or to intermediate filaments
b. Whether the linkage is between two cells or between a cell and the extracellular environment
c. The presence of cadherins versus ICAMs
d. Whether the cadherins are linked directly or indirectly to the cytoskeletal elements
A
a. The linkage of cadherins either to actin filaments or to intermediate filaments
16
Q
- Adherens junctions link to cytoplasmic
a. Actin filaments
b. Intermediate filaments
c. Microtubules
d. Myosin filaments
A
a. Actin filaments
17
Q
- Which of the following signal molecules binds to nuclear receptors?
a. Thyroid hormone
b. Vitamin D3
c. Retinoic acid
d. Steroid
e. All of the above
A
e. All of the above
18
Q
- What is the difference between Gram-positive and Gram-negative bacteria?
a. Gram-positive bacteria make gramicidin A and Gram-negative bacteria do not
b. Gram-positive bacteria are motile and Gram-negative are not
c. Gram-positive bacteria are surrounded by a single membrane and Gram-negative by two membranes, with an inner membrane that is porous to small molecules and ions
d. Gram-positive bacteria are surrounded by a single membrane, whereas Gram-negative bacteria are surrounded by a double membrane, with an outer membrane that is porous to ions and small molecules
A
d. Gram-positive bacteria are surrounded by a single membrane, whereas Gram-negative bacteria are surrounded by a double membrane, with an outer membrane that is porous to ions and small molecules
19
Q
- Animal cells are embedded in a(n)
a. Extracellular matrix
b. Hemicellulose-rich hyaluronan layer
c. Pectin-rich basal lamina
d. Cell wall
A
a. Extracellular matrix
20
Q
- Integrins link extracellular matrix proteins either directly or indirectly to all of the following intracellular proteins except
a. Talin
b. Laminin
c. Actin
d. -actinin
A
b. Laminin
21
Q
- fibrous structural proteins of the extracellular matrix are embedded in gels formed from polysaccharides called
a. fibronectin
b. glycosaminoglycans (GAGs)
c. elastin
d. laminin
A
b. glycosaminoglycans (GAGs)
Molec Cell
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