Cell Structure Chapter 17 Practice

Microglia (support cells in the brain) are connected by gap junctions. When the fluorescent dye Lucifer yellow is injected into individual microglia that are part of a large group of cells, dye passes to other cells. When microglia are treated with the calcium ionophore, 4Br-A23187, there is a dramatic decrease in dye passage between cells. The passage of molecules between cells can be regulated by the intracellular Ca2+ content. When the Ca2+ concentration is increased outside an individual cell, the movement of fluorescent molecules into that cell is inhibited, suggesting that gap junctions are closed under these conditions. "The passage of molecules between cells can be regulated by the intracellular Ca2+ content. When the Ca2+ concentration is increased in an individual cell, the movement of fluorescent molecules into that cell is increased, suggesting that gap junctions are open under these conditions. The passage of molecules between cells can be regulated by the intracellular Ca2+ content. When the Ca2+ concentration is increased outside an individual cell, the movement of fluorescent molecules from that cell is inhibited, suggesting that gap junctions are closed under these conditions. The passage of molecules between cells can be regulated by the intracellular Ca2+ content. When the Ca2+ concentration is increased in an individual cell, the movement of fluorescent molecules from that cell is inhibited, suggesting that gap junctions are closed under these conditions.

"The passage of molecules between cells can be regulated by the intracellular Ca2+ content. When the Ca2+ concentration is increased in an individual cell, the movement of fluorescent molecules into that cell is increased, suggesting that gap junctions are open under these conditions.

Which of the following statements is true regarding cell-cell adhesion? Adhesive junctions are characterized by the attachment of long molecules of hyaluronate. Adhesion is coordinated with many cellular processes except cell survival. Adherens junctions are exclusive to plant cells. Adhesion molecules include plakoglobulin, which cements two cells together. Adhesive junctions are dynamic in response to cellular signals.

Adhesive junctions are dynamic in response to cellular signals.

Which of the following is the most accurate summary concerning the common adhesive glycoproteins of the ECM, fibronectins, and laminins? Both of these proteins are extremely large adaptor-like proteins, containing multiple domains that serve as attachment sites for collagen, heparin, heparin sulfate, and cell-surface receptors. Both of these proteins are components of tight junctions and desmosomes. Both of these proteins are components of the cell wall. Both of these proteins are enzymes.

Both of these proteins are extremely large adaptor-like proteins, containing multiple domains that serve as attachment sites for collagen, heparin, heparin sulfate, and cell-surface receptors.

In animal cells, the extracellular matrix plays important roles in all of the following processes except adhesion. differentiation. cell division. motility. DNA replication.

DNA replication.

Which of the following is false with regard to the extracellular matrix? Extracellular matrices play a role in determining the shape of a cell. Extracellular matrices are only found in association with eukaryotic cells. Bone and cartilage are examples of cells that have specialized extracellular matrices associated with their function. These structures are external to the cell membrane, but are still an integral component of cell function. Extracellular matrices play a role in determining the mechanical properties of tissues and organs.

Extracellular matrices are only found in association with eukaryotic cells.

Which of the following is mismatched? cadherins-embryonic development lectins-carbohydrates IgSF[emdash]chondroitin cadherins-calcium ions selectins-leukocytes

IgSF[emdash]chondroitin

Loewenstein and colleagues injected cells with fluorescent molecules of different molecular weights, and a fluorescence microscope was then used to observe the movement of the molecules into adjacent cells. When molecules with molecular weight of 1926 were injected, they did not pass from cell to cell, but molecules with molecular weight of 1158 did. The gap junctions that connect adjacent cells in insect salivary glands allow the passage of small molecules (molecular weight up to at least 1158 daltons), whereas larger molecules (1926 daltons) do not flow between cells. The gap junctions that connect adjacent cells in insect salivary glands allow the passage of small molecules (molecular weight up to at least 1158 daltons), whereas larger molecules (1926 daltons) unexpectedly attach to the cell receptors. The gap junctions that connect adjacent cells in insect salivary glands block the passage of small molecules (molecular weight up to at least 1158 daltons), whereas larger molecules (1926 daltons) flow between cells. The gap junctions that connect adjacent cells in insect salivary glands allow the passage of both small molecules (molecular weight up to at least 1158 daltons), as well as larger molecules (1926 daltons) to flow between cells.

The gap junctions that connect adjacent cells in insect salivary glands allow the passage of small molecules (molecular weight up to at least 1158 daltons), whereas larger molecules (1926 daltons) do not flow between cells.

Which of the following experimental treatments would NOT be a potentially effective strategy to inhibit or prevent cell-cell adhesion? removal of calcium ions from the extracellular space adding an antagonist to prevent integrin function application of a protease that specifically destroys CAMs application of an antibody that inhibits the function of lectins

adding an antagonist to prevent integrin function

Focal contact is associated with which of the following type of cellular junction? plasmodesmata tight junctions gap junction adhesive junction all of the above

adhesive junction

Which of the following cell junctions are associated with the proper alignment of intestinal epithelial cells? tight junctions gap junctions adhesive junctions desmosomes all of the above

all of the above

Which of the following is not associated with adhesive junctions? cadherins plaques connexin desmosomes hemidesmosomes

connexin

Polarized cells are characterized by random orientation within an organ. distinct apical and basolateral sides. a polar flagellum. random orientation within a tissue. a polar flagellum and distinct apical and basolateral sides.

distinct apical and basolateral sides.

Collagens are NOT __________. the most abundant component of the extracellular matrix in animals load-bearing proteins in the extracellular matrix found as bundles of double-helical polypeptides high in glycine, hydroxylysine, and hydroxyproline

found as bundles of double-helical polypeptides

In the extracellular matrix of animal cells, collagen and elastin fibers are embedded with this matrix. glycoaminoglycans proteoglycans pectins lignins glycoaminoglycans and proteoglycans

glycoaminoglycans and proteoglycans

A type of adhesive junction that is associated with the connection between an epithelial cell and the basal lamella is the desmosome. plasmodesmata. focal contact. gap junction. hemidesmosome.

hemidesmosome.

The molecule of the extracellular matrix of animal cells that is associated with joint lubrication and friction reduction is hyaluronate. pectin. proteoglycan. fibronectin. glycosaminoglycan.

hyaluronate.

For a cancerous tumor to move from tissue to tissue in metastasis, which proteins of the basal lamina must it be able to degrade or pass through? laminins and type IV collagen cadherins and lectins plectin and actin claudins and CAMs

laminins and type IV collagen

You are investigating cell localization by targeting the carbohydrates associated with various cell types. Based on this molecule's ability to bind various carbohydrates, which of the following would help determine which carbohydrates are found on the cell surface? proteoglycans lectins connexins cadherins pectins

lectins

Collagens are associated with which of the following types of cellular junctions? gap junctions adhesive junctions tight junctions plasmodesmata none of the above

none of the above

Which of the following activities is not associated with cadherins? loss of activity associated with cancer segregation of cells to specific tissues paracellular transport embryonic development establishment of synaptic connections

paracellular transport

A collection of fibrous intracellular attachment proteins is called a(n) annulus. connexon. plaque. tonofilament. plaque and tonofilament.

plaque.

In performing research, you treat frog zygotes with antibodies that bind E-cadherin. As a result, you expect no change with regard to development. the cells to become exclusively muscle tissue. the cells to be loosely associated and abort development. the cells to be loosely associated and develop into a novel strain of frog. the cells to divide uncontrollably.

the cells to be loosely associated and abort development.

The type of cellular junction prominent in the stomach and kidney is the plasmodesmata. laminin junction. adhesive junction. gap junction. tight junction.

tight junction.

Paracellular transport is associated with which of the following? tight junctions hemidesmosomes desmosomes integrins adherens junctions

tight junctions