Cell Bio: Chapter 7

Which of the following statements about integrins is true? a) They anchor cells to the substrate. b) They are found in both animal and plant cells. c) Different cell types are restricted to just one type of integrin. d) All of these statements are true.

a) They anchor cells to the substrate.

What ion is required to maintain the proper integrin structure and to facilitate ligand binding? a) calcium b) magnesium c) sodium d) manganese

a) calcium

Desmosomes are ________. a) disk-shaped adhesive junctions. b) restricted to cardiac muscle tissue. c) devoid of cadherins, but rich in intermediate filaments. d) all of these are correct answers

a) disk-shaped adhesive junctions.

Which animal cell structure do plasmodesmata in plants most closely resemble? a) gap junctions b) spot desmosomes c) zonulae adherens d) maculae adherens

a) gap junctions

What forms the barrier of the tight junctions that seals off the space between adjacent cells? a) paired rows of aligned integral membrane proteins b) paired rows of aligned phospholipids c) paired rows of carbohydrates d) interdigitating integral membrane proteins

a) paired rows of aligned integral membrane proteins

The bonds that selectins form with their ligands become _______ when the interaction is __________. a) stronger, placed under mechanical stress. b) weaker, placed under mechanical stress. c) stronger, exposed to a higher temperature. d) more elastic, exposed to a higher temperature.

a) stronger, placed under mechanical stress.

Metastatic cells are distinguished by the fact that _________. a) they are less adhesive than other cells. b) they are able to penetrate the basement membranes lining blood vessels. c) they are unable to invade other tissues, while normal cells can. d) they are less adhesive than other cells and they are able to penetrate the basement membranes lining blood vessels

a) they are less adhesive than other cells.

The mechanical properties of extracellular matrix are provided by _________. a) laminin. b) collagen. c) fibronectin. d) all of these answers are correct.

b) collagen.

From the basal surface to the apical surface of an epithelial cell, what is the order of cell junctions observed in the junctional complex? a) tight junction, belt desmosome, spot desmosomes/gap junctions b) gap junctions/spot desmosomes, belt desmosomes, tight junctions c) belt desmosome, tight junction, spot desmosomes/gap junctions d) belt desmosome, spot desmosomes/gap junctions, tight junctions

b) gap junctions/spot desmosomes, belt desmosomes, tight junctions

Which tight junction will form a tighter seal? a) one with a single strand of aligned integral membrane proteins b) one with a number of parallel, interconnected strands of aligned integral membrane proteins c) tight junctions containing a special kind of phospholipid d) tight junctions containing a special kind of carbohydrate

b) one with a number of parallel, interconnected strands of aligned integral membrane proteins

Some animals are found to be lacking a gene required to assemble epidermal tight junctions. What is a possible medical condition among those animals? a) an impermeable blood-brain barrier b) uncontrolled water loss c) defective antibodies d) All of these answers are correct.

b) uncontrolled water loss

Which of the following phrases does NOT describe a function of the glycocalyx? a) It mediates cell-cell and cell-substratum interactions. b) It provides mechanical protection for cells. c) It serves as a passageway for particles to reach the plasma membrane. d) It binds important regulatory factors that act on the cell surface.

c) It serves as a passageway for particles to reach the plasma membrane.

Which of the following statements about the basement membrane is false? a) It is a continuous sheet. b) It underlies the basal surface of epithelial tissues. c) Its only function is to provide mechanical support for attached cells. d) All of these statements are true.

c) Its only function is to provide mechanical support for attached cells.

Epithelial tissues _________. a) consist of extracellular materials, including a variety of distinct fibers. b) often contain cells scattered throughout the tissue. c) contain tightly packed cells and line spaces within the body. d) all of these are correct.

c) contain tightly packed cells and line spaces within the body.

You are charged with designing an artificial organ that requires all of its cells to communicate with one another effectively for proper functioning. What type of cell junction should you include when designing such an organ? a) adherens junctions b) tight junctions c) gap junctions d) none of these is the correct answer

c) gap junctions

Which structure forms an anchoring structure to the basement membrane for epithelial cells in vivo and yields an attachment that is regarded to be the tightest attachment within the human body between a cell and its extracellular matrix? a) laminin b) focal adhesions c) hemidesmosomes d) all of these are correct answers

c) hemidesmosomes

What kind of cell adhesion molecule mediates transient interactions between circulating leukocytes and vessel walls at inflammation and clotting sites? a) IgSFs b) integrins c) selectins d) cadherins

c) selectins

Cadherins appear to be important in holding cells together in __________ tissues. a) mesenchymal b) gel-like c) tightly cohesive d) noncohesive

c) tightly cohesive

Focal adhesions ________. a) contain integrins that develop transient interactions with the extracellular matrix. b) collect information about the chemical properties of the extracellular environment. c) transmit information to the cell interior that may lead to changes in cell adhesion, proliferation or survival. d) all of these answers are correct.

d) all of these answers are correct.

Which cell junction prevents the movement of solutes between the cells of an epithelial layer? a) zonulae adherens b) zonulae occludens c) tight junctions d) zonulae occludens and tight junctions

d) zonulae occludens and tight junctions