Chapter 7 - Cell Bio

Focal adhesions ________. contain integrins that develop transient interactions with the extracellular matrix. collect information about the chemical properties of the extracellular environment. transmit information to the cell interior that may lead to changes in cell adhesion, proliferation or survival.

All of these answers are correct

Possible reasons why metastatic cancer cells are less adhesive include: these cells induce surrounding normal cells to produce matrix metalloproteinases. reduced levels of E-cadherins. both of these choices. neither of these choices.

Both of these choices

You coat a Petri dish with fibronectin and proteoglycans and then culture cells on the dish. The cells adhere to the dish. You repeat the experiment, but this time you add RGD (arginine-glycine-aspartic acid) tripeptides to the culture dish as the cells are added. What happens? The cells adhere as they normally do. The cells immediately change their phenotype. The cells lyse and die immediately. The cells do not adhere to the dish.

The cells do not adhere to the dish.

Which of the following statements about focal adhesions is true? They anchor cells to the substratum. They can be rapidly disassembled upon a changing environment. They may act as a type of sensory structure leading to cell growth.

All of these answers are correct

Which of the following statements about gap junctions is true? They are found in animal cells only. They are composed of the protein connexin. They are specialized for intercellular communication.

All of these answers are correct

How are gap junctions and plasmodesmata different? Gap junctions are found in animal cells and plasmodesmata are found in plant cells. Gap junctions are found in plant cells and plasmodesmata are found in animal cells. Gap junctions are capable of dilation whereas plasmodesmata are rigid.

Gap junctions are found in animal cells and plasmodesmata are found in plant cells.

Calcium-dependent adhesion is to the cadherins as calcium-independent adhesion is to the __________. IgSF proteins fibronectins integrins glycocalyx

IgSF proteins

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

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

To which category of proteins listed below are NCAM and VCAM most closely related? proteoglycans antibodies integrins selectins

antibodies

Integrin is to a focal adhesion as ________ is to an adherens junction. integrin selectin fibronectin cadherin

cadherin

A student treated some cells with an agent that sequesters calcium from the medium. Which of the following proteins would most likely be affected in their cell-to-cell adhesion? immunoglobulins fibronectin cadherins integrins

cadherins

The molecules found within a pant cell wall include: cellulose, pectin, hemicellulose and glycolipids. cellulose, pectin, hemicellulose and glycoproteins. lignin, glycogen, cellulose and glycolipids. none of these.

cellulose, pectin, hemicellulose and glycoproteins

What kind of tissue consists largely of extracellular material, including a variety of distinct fibers that interact with each other in specific ways, with cells scattered throughout it? epidermis epithelium connective tissue epidermis and epithelium

connective tissue

Epithelial tissues _________. consist of extracellular materials, including a variety of distinct fibers. often contain cells scattered throughout the tissue. contain tightly packed cells and line spaces within the body.

contain tightly packed cells and line spaces within the body.

Plasmodesmata of plant cells have _________ in common with gap junctions in animal cells, but have _________ that gap junctions lack. connexin, connexon cytoplasmic continuity, desmotubules movement proteins, cytoplasmic continuity desmotubules, cell walls

cytoplasmic continuity, desmotubules

Which of the following cell types might have the highest number of desmosomes? smooth muscle cells red blood cells epithelial cells of the skin nerve cells

epithelial cells of the skin

What could be defined as an organized network of extracellular materials found beyond the immediate vicinity of the plasma membrane? intracellular matrix extracellular matrix extracellular material epicellular matrix

extracellular matrix

Animal cells can share some metabolites, such as ATP and coenzymes. Which structure below allows the sharing of these materials? tight junctions gap junctions adherens junctions plasmodesmata

gap junctions

Cells of the heart must contract in synchrony to produce an effective heart beat. The electrical signal telling each cell to contract must reach every cell of the heart at the same time. What kind of cell-to-cell junctions would you expect to find in heart tissue? gap junctions tight junctions desmosome adherens junctions

gap junctions

Which animal cell structure do plasmodesmata in plants most closely resemble? gap junctions spot desmosomes zonulae adherens maculae adherens

gap junctions

The addition of a peptide with an RGD sequence would probably _________ the binding of cultured cells with α3β1 surface receptors to a collagen-coated or laminin-coated dish. enhance inhibit have no effect on none of these

have no effect on

________ are members of an integral membrane glycoprotein family that bind to specific sugar arrangements in oligosaccharides that project from the surfaces of other cells. Selectins Integrins Immunoglobulin super family proteins Cadherins

selectins

Focal adhesions are common in cultured cells and found in vivo in: dermis to epidermis connections. muscle cell to tendon connections. cartilage to bone connections. bone to ligament connections.

muscle cell to tendon connections

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

stronger, placed under mechanical stress

From what cell organelle does the desmotubule appear to be derived? the SER of the two cells the RER of the two cells the Golgi apparatus of the two cells the cell wall of both cells

the SER of the two cells

You are studying a plant and inject fluorescein, a fluorescent dye, into a single cell on the surface of the plant. After a brief period of time, the dye spreads to cells neighboring the injected cell. What do you conclude? The cells are connected by the cell wall. The cells are connected by tight junctions. The cells are connected by plasmodesmata. The cells are connected by gap junctions.

the cells are connected by plasmodesmata

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

they are less adhesive than other cells

In going from the apical to the basal end of an epithelial cell, in what order do the various cell surface junctions appear? tight junction→adherens junction→desmosomes→hemidesmosomes desmosomes→hemidesmosomes→adherens junction→tight junction adherens junction→tight junction→desmosomes→hemidesmosomes tight junction→adherens junction→hemidesmosomes→desmosomes

tight junction→adherens junction→desmosomes→hemidesmosomes

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

zonulae occludens and tight junctions

Embryos injected with antibodies to fibronectin show inhibited movement of neural crest cells during development of the nervous system. These experiments show that: development of the neural crest involves the expression of antibody genes. developing neurons must synthesize fibronectin. fibronectin-antibody complexes form pathways for neural migration. neurons in embryos must transiently bind to fibronectin during migration.

neurons in embryos must transiently bind to fibronectin during migration

How might anti-selectin antibodies act as anti-inflammatory drugs? Anti-selectin antibodies prevent activated endothelial cells from expressing selectin. Anti-selectin antibodies compete with carbohydrate ligands on neutrophil surfaces for selectin binding sites. Anti-selectin antibodies prevent neutrophils from transiently binding vessel walls. Anti-selectin antibodies prevent activated endothelial cells from producing platelet activating factor.

Anti-selectin antibodies prevent neutrophils from transiently binding vessel walls

Although the protein families that comprise the ECM are very different, they have one of the following characteristics in common: They all have specific binding sites for one another and for cell surface receptors. They are all derived from proteins of the immune system. They all have membrane-spanning domains. None of them are attached to the cell.

They all have specific binding sites for one another and for cell surface receptors.

The tightest attachment between a cell and its extracellular matrix is seen at the site where an epithelial cell is attached to the underlying basement membrane. The specialized adhesive structure found at such a site is called a(n) ________. tight junction spot desmosome plasmodesma hemidesmosome

hemidesmosome

Which of the following proteins of the ECM has a membrane bilayer-spanning domain? fibrillar collagen heparan sulfate proteoglycans fibronectin laminin

heparan sulfate proteoglycans

Despite the presence of the blood-brain barrier, what cells, oddly enough, can pass through the blood-brain barrier by sending a signal that opens up the junction? red blood cells immune system cells platelets epithelial cells

immune system cells

If a laboratory mouse had a mutation rendering the gene that codes for the E-selectin and P-selectin proteins nonfunctional, which of the following symptoms would the animal exhibit? blistering of the skin clotting deficiencies metastasis inability to fight infection in the tissues

inability to fight infection in the tissues

The addition of a peptide with an RGD sequence would probably _______ the binding of cultured cells with α3β1 surface receptors to a fibronectin-coated dish. enhance inhibit have no effect on none of these

inhibit

Which of the following is not a role of integrins? Integrins may associate with sodium ions. Integrins anchor cells to the substrate. Integrins transmit signals to the intracellular compartment. Integrins participate in "inside-out" signaling.

integrins may associate with sodium ions

Which of the following is not an example of a type of extracellular matrix? basement membrane the cornea of the eye intermediate filaments bone

intermediate filaments

Actin filaments are to focal adhesions as __________ are to hemidesmosomes. myosin filaments keratin filaments microfilaments cadherins

keratin filaments