Deck 7: Interactions Between Cells and Their Environment

Question 1

If extracellular matrix materials are added back to the cells described in question #2,what happens?

A)Nothing happens.
B)Everything happens.
C)The differentiated state of the cells is restored and the cells produce their usual products.
D)The cells die.
E)The cells dedifferentiate.

Answer 1

C

Question 2

Collagen fibrils are strengthened by covalent cross-links between _____ and ____ residues on adjacent collagen molecules.

A)lysine,hydroxylysine
B)proline,hydroxyproline
C)lysine,hydroxyproline
D)proline,hydroxylysine
E)proline,lysine

Answer 2

A

Question 3

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

A)intracellular matrix
B)extracellular matrix
C)extracellular netrax
D)intercellular material
E)epicellular matrix

Answer 3

B

Question 4

Type II collagen mutations alter the properties of cartilage tissue and are known to cause _______.

A)osteogenesis imperfecta
B)Ehler-Danlos syndromes
C)Alport syndrome
D)dwarfism and skeletal deformities
E)diabetes

Question 5

You place mammary gland epithelial cells in culture and then treat them with enzymes that digest the surrounding extracellular matrix.What happens?

A)The secretory and synthetic activities of the cells decrease.
B)The secretory and synthetic activities of the cells increase.
C)The cells die.
D)The cells enunciate.
E)The secretory and synthetic activities of the cells do not change.

Question 6

You are investigating the interactions of integrin $\alpha$ and $\beta$ subunits and isolate the extracellular portion of an integrin as a soluble $\alpha$ / $\beta$ heterodimer.The heterodimer lacks the associated transmembrane and cytoplasmic domains normally present as part of the molecule.You experimentally link the $\alpha$ and $\beta$ subunits at the bases of their legs so that the ligand-binding regions of the $\alpha$ and $\beta$ subunits approach one another.Which of the following statements is true about the molecules formed?

A)The molecules bind their ligand tightly.
B)The molecules are unable to bind a ligand.
C)The molecules are cleaved.
D)The molecules denature their ligand.
E)The molecules denature and degrade.

Question 7

All collagen family members consist of _____ chains arranged in a _______.

A)2,double helix
B)3,double helix
C)3,triple helix
D)3,triple lattice
E)2,triple helix

Question 8

Mutations in other collagen genes can lead to a variety of distinct but related defects in collagen matrix structure,one of which causes hyperflexible joints and highly extensible skin.These defects are usually referred to as ______.

A)osteogenesis imperfecta
B)Ehler-Danlos syndromes
C)Alport syndromes
D)Cushing's syndrome
E)diabetes

Question 9

What integral membrane protein family made of two membrane-spanning chains ( $\alpha$ and $\beta$ )is involved in attaching cells to their extracellular microenvironment?

A)laminins
B)fibronectins
C)integrins
D)myosins
E)lysins

Question 10

Evidence strongly suggests that the bent conformation of an integrin is _______ and unable to bind its ligand.

A)loose
B)active
C)tight
D)stretched
E)inactive

Question 11

Type I collagen mutations cause a potentially lethal condition characterized by extremely fragile bones,thin skin and weak tendons.This condition is called _______.

A)osteogenesis imperfecta
B)Ehler-Danlos syndrome
C)Alport syndrome
D)dwarfism and skeletal deformities
E)diabetes

Question 12

The basal lamina of which structure may thicken abnormally in long-term diabetics causing kidney failure?

A)the dermis
B)the epidermis
C)the glomerulus
D)the bladder epithelium
E)the pericardium

Question 13

What substance joins proteoglycans together into gigantic complexes called proteoglycan aggregates? These complexes can occupy very large volumes.

A)hyaluronidase
B)hyaluronic acid
C)proteoglycase
D)fibronectin
E)laminin

Question 14

In an integrin,what structure is it that crosses the lipid bilayer?

A)a transmembrane pleated sheet
B)a transmembrane spear
C)a transmembrane plate
D)a transmembrane helix
E)a bent,curved leg

Question 15

What would be the effect on primordial germ cells when an embryo is exposed to laminin-specific antibodies?

A)They arrive at the developing gonad more quickly.
B)Their movement to the developing gonad is disrupted.
C)They begin to divide rapidly.
D)They increase greatly in size.
E)Their nuclei disintegrate.

Question 16

The activation of a membrane integrin by the binding of its cytoplasmic portion to molecules in the cytoplasm and the resultant increase in its affinity for an extracellular ligand is called ________.

A)inside-out signaling
B)outside-in signaling
C)right-side-out signaling
D)simple signaling
E)integrination

Question 17

The degradation of the extracellular matrix,along with cell surface proteins,is accomplished mostly by a _____-containing enzyme family called _______.

A)copper,matrix metalloproteinases
B)copper,MMPs
C)zinc,matrix metalloproteinases
D)magnesium,matrix metalloproteinases
E)manganese,MMPs

Question 18

Basement membranes contain Type IV collagen,a nonfibrillar collagen organized in a flattened network.The Type IV collagen trimer has some interspersed nonhelical segments.What property does this confer upon basement membranes?

A)strength
B)flexibility
C)extensibility
D)transparency
E)opacity

Question 19

In the corneal stroma,the uniformity of collagen fiber size and the ordered packing of the fibers confers what property on the corneal stroma?

A)strength
B)flexibility
C)extensibility
D)transparency
E)opacity

Question 20

If antibodies to fibronectin are exposed to an embryo through which neural crest cells are migrating,what happens?

A)Neural crest cell movements are inhibited.
B)Neural crest cell movements are excited.
C)Neural crest cells die.
D)Neural crest cells divide.
E)Neural crest cells convert into muscle cells.

Question 21

Epidermolysis bullosa,an inherited blistering disease,is caused by ________.

A)production of antibodies against hemidesmosome plaque proteins
B)production of autoantibodies
C)production of antibodies against spot desmosome plaque proteins
D)genetic alterations in any one of a number of hemidesmosomal proteins
E)production of antibodies against connexins

Question 22

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)________.

A)tight junction
B)spot desmosome
C)plasmodesma
D)hemidesmosome
E)gap junction

Question 23

Focal adhesions ________.

A)may act as a type of sensory structure
B)collect information about the physical properties of the extracellular environment
C)collect information about the chemical properties of the extracellular environment
D)transmit information to the cell interior that may lead to changes in cell adhesion,proliferation or survival
E)All of these are correct.

Question 24

Focal adhesions ________.

A)have been implicated in cell locomotion
B)contain integrins that develop transient interactions with the extracellular matrix
C)collect information about the chemical properties of the extracellular environment
D)transmit information to the cell interior that may lead to changes in cell adhesion,proliferation or survival
E)All of these are correct.

Question 25

Which of the following proteins are known to be associated with focal adhesions?

A)actin
B)aconitase
C)myosin
D)malin
E)actin and myosin

Question 26

Filaments connected to the dense plaque underlying the membrane in a hemidesmosome course outward into the cytoplasm.These filaments are composed of the protein _____ and are best known as ______.

A)actin,microfilaments
B)keratin,microfilaments
C)actin,intermediate filaments
D)keratin,intermediate filaments
E)tubulin,intermediate filaments

Question 27

Why do cells flatten out as they make contact with a surface?

A)They lose water.
B)They extrude cytoplasm.
C)They send out projections that make increasingly stable attachments.
D)Their membranes stiffen.
E)They make focal assignations.

Question 28

To what is the cytoplasmic domain of integrins in the region of a focal contact connected via various adaptors?

A)tubulins of the cytoskeleton
B)actinin of the cytoskeleton
C)actin of the cytoskeleton
D)dynein of the cytoskeleton
E)band III protein of the membrane

Question 29

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

A)Selectins
B)Integrins
C)Immunoglobulin super family proteins
D)Cadherins
E)Calmodulins

Question 30

What proteins have been shown to be altered by genetic mutations in patients who suffer from epidermolysis bullosa?

A)the $\alpha$ ₆ integrin subunit
B)the $\beta$ ₄ integrin subunit
C)collagen VII
D)laminin-5
E)All of these are correct.

Question 31

What ion is not known to bind to integrins?

A)calcium
B)magnesium
C)sodium
D)divalent cations
E)manganese

Question 32

What kind of experiments have provided evidence that most integrins have unique functions?

A)enzyme assays
B)gene addition experiments
C)gene knockout experiments
D)freeze-fracture,freeze etch experiments
E)sucrose density centrifugation

Question 33

The filaments associated with hemidesmosomes are __________.

A)actin filaments
B)keratin filaments
C)microtubules
D)intermediate filaments
E)keratin filaments and intermediate filaments

Question 34

If experimentally linked $\alpha$ / $\beta$ heterodimer integrin subunits are separated,what happens?

A)The molecules bind their ligand tightly
B)The molecules are unable to bind a ligand.
C)The molecules are cleaved.
D)The molecules denature their ligand.
E)The molecules are denatured and degraded.

Question 35

Which disease is an inherited blistering disease that can occur in patients with genetic alterations in any one of a number of hemidesmosomal proteins,including the $\alpha$ ₆ or $\beta$ ₄ integrin subunit,collagen VII or laminin-5?

A)epidermolysis bullosa
B)bullous pemphigoid
C)blisterosis
D)hemidesmosomosis
E)eczema

Question 36

You disaggregate cells from two different developing organs and mix them together.Initially,they form a mixed clump.What happens next?

A)The clump stabilizes.
B)The cells sort themselves out so that each cell adhered only to cells of the same type.
C)The mixed clump persists.
D)The clumped cells die.
E)The clump forms a mesenchyme.

Question 37

In which disease do individuals produce antibodies that bind to proteins present in hemidesmosmes? It causes the lower layer of the epidermis to lose attachment to the underlying basement membrane and thus to the underlying connective tissue layer of the dermis.The leakage of fluid into the space beneath the epidermis results in severe blistering of the skin.

A)epidermolysis bullosa
B)bullous pemphigoid
C)blisterosis
D)hemidesmosomosis
E)eczema

Question 38

Cells were allowed to bind to beads that had been covered with a coating of fibronectin.When the membrane-bound beads were pulled by an optical tweezer,the resultant mechanical stimulus was transmitted into the cell interior.What response did this cause?

A)It generated a wave of Src kinase activity.
B)It caused nuclear shrinkage.
C)It caused activation of phosphofructokinase.
D)It caused inhibition of phosphofructokinase.
E)It inhibited Src kinase activity.

Question 39

You coat a Petri dish with fibronectin and proteoglycans and culture cells on the dish.The cells adhere to the dish.You repeat the experiment but this time add RGD tripeptides to the culture dish as the cells are added.The result of this experiment is an example of what biochemical process?

A)competitive inhibition
B)noncompetitive inhibition
C)enzymatic activation
D)feedback inhibition
E)allosterism

Question 40

You coat a Petri dish with fibronectin and proteoglycans and culture cells on the dish.The cells adhere to the dish.You repeat the experiment but this time add RGD tripeptides to the culture dish as the cells are added.What happens?

A)The cells adhere as they normally do.
B)The cells die immediately.
C)The cells lyse immediately.
D)The cells do not adhere to the dish.
E)The cells immediately change their phenotype.

Question 41

What type of cell adhesion molecule is associated with cells being held together by adherens junctions at the site of the junction?

A)adherins
B)selectins
C)IgSFs
D)integrins
E)cadherins

Question 42

Lymphocytes are isolated and labeled with radioactive isotopes.They are then exposed to frozen tissue sections of a lymphoid organ.What happens?

A)The lymphocytes bind uniformly to the sections.
B)The lymphocytes bind to each other.
C)The lymphocytes selectively adhere to the endothelial lining of venules in peripheral lymph nodes.
D)The lymphocytes selectively adhere to the endothelial lining of arterioles in peripheral lymph nodes.
E)The lymphocytes do not stick to the sections.

Question 43

You genetically engineer nonadhesive cells to express one variety of cadherins and then mix the cells in various combinations.You then monitor their interactions.What do you observe?

A)The genetically engineered cells adhered preferentially to cells expressing one of the other cadherins.
B)The genetically engineered cells adhered preferentially to cells expressing the same cadherins.
C)The genetically engineered cells did not stick to any other cells.
D)The genetically engineered cells died.
E)The genetically engineered cells migrated to a different location.

Question 44

What can be described as solitary,nonadhesive,nonpolarized migratory cells?

A)a mesenchyme
B)cartilage
C)an epithelium
D)a mesothelium
E)an endothelium

Question 45

What is thought to be the origin of immunoglobulins?

A)They may be derived from immune system molecules in invertebrates.
B)They may be derived from cell-adhesion receptors in invertebrates.
C)They may be derived from cell-adhesion receptors in fish.
D)They may be derived from cell-adhesion molecules in amphibians.
E)They may be derived from immune system molecules in reptiles.

Question 46

Which of the following tissues are typically derived from mesenchymal cells?

A)mesodermal tissues
B)ectodermal tissues
C)only blood
D)only muscle
E)mesodermal tissues,blood and muscle

Question 47

The cells of the epiblast of a developing mammalian embryo display what cell adhesion molecules on their surfaces,molecules that presumably promote their close association with one another?

A)selectins
B)E-cadherins
C)P-cadherins
D)integrins
E)IgSFs

Question 48

From the apical surface to the basal 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)tight junction,gap junction,belt desmosome,spot desmosomes
C)belt desmosome,tight junction,gap junctions,spot desmosomes
D)belt desmosome,gap junctions,tight junctions,spot desmosomes
E)gap junctions,spot desmosomes,belt desmosome,tight junction

Question 49

Calcium ions form bridges between ________.

A)successive domains of a given cadherin molecule
B)cadherins on adjacent cells
C)cadherins on the same cell
D)cadherins and IgSFs
E)IgSFs and selectins

Question 50

The binding of lymphocytes to the endothelial lining of venules in peripheral lymph node frozen tissue sections could be blocked in what way? This demonstrated the existence of what kind of molecule?

A)Treatment with antibodies against specific lymphocyte surface glycoproteins,selectins
B)Treatment with antibodies against specific lymphocyte surface glycoproteins,IgSFs
C)Treatment with antibodies against specific lymphocyte surface glycoproteins,integrins
D)Treatment with antibodies against specific ECM glycoproteins,selectins
E)Treatment with antibodies against specific ECM glycoproteins,cadherins

Question 51

L1 is an IgSF molecule that has been shown to be important in neural development; it is thought that it may be involved in axon growth within the embryonic nervous system.What evidence supports this statement?

A)L1 mutants always die.
B)L1 mutants show deficits in their vision.
C)People who die of L1-deficiency are often missing two large nerve tracts.
D)People who die of L1-deficiency are often missing a significant portion of their brain.
E)People who die of L1-deficiency are often missing a significant portion of their spinal cord.

Question 52

While most IgSF members are involved in various aspects of immune function,some of them mediate ________ cell-cell adhesion.

A)calcium-dependent
B)calcium-independent
C)magnesium-dependent
D)manganese-dependent
E)iron-independent

Question 53

What can be described as a tightly adherent,polarized cell layer?

A)a mesenchyme
B)cartilage
C)an epithelium
D)a mesothelium
E)mesoderm

Question 54

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
E)more elastic,placed under mechanical stress

Question 55

What is the function of most IgSFs?

A)cell adhesion
B)cell division
C)mediating specific interactions of epithelial cells with cells needed for immune response
D)mediating specific interactions of lymphocytes with cells needed for the immune response
E)cell fusion

Question 56

Cadherins appear to be important in holding cells together in __________ tissues.

A)mesenchymal
B)loosely cohesive
C)tightly cohesive
D)noncohesive
E)gel-like

Question 57

What determines the strength of adhesion between apposing cells held together by cadherins?

A)the length of the cadherins connecting the cells
B)the width of the cadherins connecting the cells
C)the amount of tryptophan in the cadherins connecting the cells
D)the number of cadherins in a cluster connecting the cells
E)the number of tyrosine residues in the cadherins connecting the cells

Question 58

When tight junctions,gap junctions and desmosomes are arranged in a specific array,the assortment of surface specializations is called a(n)__________.

A)junctional array
B)synaptonemal complex
C)belt complex
D)junctional complex
E)spot complex

Question 59

The loss of cadherin function may be instrumental in what disease state?

A)colds
B)the spread of benign tumors
C)the spread of malignant tumors
D)influenza
E)AIDS

Question 60

Which of the following tissues are typically not derived from mesenchymal cells?

A)mesodermal tissues
B)ectodermal tissues
C)blood
D)muscle
E)bone

Question 61

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?

A)red blood cells
B)immune system cells
C)platelets
D)complement cells
E)epithelial cells

Question 62

During gap junction formation,connexons in apposing cells become tightly connected through extensive noncovalent interactions of __________.

A)connexin subunit intracellular domains
B)connexin subunit extracellular domains
C)connexin carbohydrates
D)connexin lipids
E)polynucleotides

Question 63

What explains the fact that plants lack the specialized junctions seen in animal cells?

A)the presence of the large central vacuole
B)the presence of chloroplasts
C)the presence of the cell wall
D)the presence of mitochondria
E)the absence of centrioles,basal bodies,cilia and flagellae

Question 64

Which tissues below are typically derived from the single-celled epithelium on the dorsal surface of a chick embryo after gastrulation?

A)muscle
B)skin,ectodermal tissues and nervous system
C)only skin
D)only ectodermal tissues
E)only tissues of nervous system

Question 65

Which tissues below are typically derived from the cells on the dorsal surface of a mammalian embryo after gastrulation that express N-cadherins and stop expressing E-cadherins?

A)skin
B)only brain
C)only spinal cord
D)only neural tube
E)brain,spinal cord and neural tube

Question 66

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)paired rows of polynucleotides
E)interdigitating integral membrane proteins

Question 67

Animals lacking the claudin-1 gene suffered from ___________.

A)uncontrolled water loss
B)high salt loading
C)low salt loading
D)Mg²⁺ ion permeability
E)constant,unremitting pain

Question 68

A new type of communication system has been discovered that consists of thin,highly elongated tubules capable of conducting cell-surface proteins,cytoplasmic vesicles and calcium signals from one cell to another.This system is referred to as ________.

A)T tubules
B)scanning tunneling EMs
C)tunneling nanotypes
D)tunneling nanotubes
E)sarcoplasmic tubules

Question 69

Pemphigus vulgaris __________.

A)is characterized by a loss of epidermal cell-cell adhesion
B)is an autoimmune disease
C)is characterized by severe blistering of the skin
D)is caused by the production of antibodies against one of the desmogleins
E)All of these are correct.

Question 70

What is thought to promote the release of future mesoderm cells from an epithelium and their transformation into mesenchymal cells?

A)a stoppage in the expression of E-cadherin genes
B)an increase in the expression of E-cadherin genes
C)degradation of the cell membrane
D)the cytoplasm taking on an anti-adhesive character
E)autophagy of the nucleus

Question 71

Which tissues below are not typically derived from the cells on the dorsal surface of a mammalian embryo after gastrulation that express N-cadherins and stop expressing E-cadherins?

A)skin
B)brain
C)spinal cord
D)neural tube
E)None of these are correct.

Question 72

Desmosomes are particularly numerous in tissues _____________.

A)that are subjected to mechanical stress
B)like cardiac muscle
C)like the epithelial layers of the skin
D)like the epithelial layers of the uterine cervix
E)All of these are correct.

Question 73

The opening in the center of a connexon that allows the passage of solutes between cells is called a(n)________.

A)connexin
B)annulus
C)cumulous
D)lunulus
E)limulus

Question 74

Each connexon in a gap junction is constructed of ___ connexin subunits.

A)2
B)4
C)6
D)8
E)10

Question 75

Which animal cell structure do plasmodesmata in plants most closely resemble?

A)maculae adherens
B)spot desmosomes
C)zonulae adherens
D)gap junctions
E)zonulae occludens

Question 76

Attachment of an integrin to its ligand can induce which of the following responses within a cell?

A)changes in cytoplasmic pH
B)changes in cytoplasmic C2⁺ ion concentration
C)protein phosphorylation
D)gene expression
E)All of these are correct.

Question 77

Which tissues below are not typically derived from the single-celled epithelium on the dorsal surface of a chick embryo after gastrulation?

A)muscle
B)skin,ectodermal tissues and nervous system
C)skin
D)ectodermal tissues
E)nervous system

Question 78

One small region of a human kidney tubule known as the thick ascending limb (or TAL)has tight junctions that are permeable to magnesium (Mg²⁺)ions.What is thought to account for the permeability of this tight junction to magnesium ions?

A)The membrane in this region is leaky because of special phospholipids.
B)Loops of claudin molecules that extend into the extracellular space form pores in the TAL.
C)Loops of claudin molecules that extend into the cytoplasm form pores in the TAL.
D)Loops of claudin molecules fully embedded in the TAL membrane form pores in the TAL.
E)Claudin molecules form gap junctions that allow the passage of magnesium ions.

Question 79

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
E)one with a number of parallel,interconnected strands of interdigitated integral membrane proteins

Question 80

What kind of molecule does not pass through a gap junction?

A)ions
B)cAMP
C)inositol phosphates
D)ribosomes
E)cGMP