Karp's Cell and Molecular Biology: Ch 7. Interactions Between Cells and Their Environment Flashcards

The glycocalyx on the outer surface of the plasma membrane:

is missing from cells that line the digestive tract.
is also called the basal lamina.
can mediate cell-to-cell and cell-substratum interactions.
is found under the dermis of the skin.
is composed of lipids and proteins.

The extracellular matrix:

is capable of renewal and remodeling.
is unaffected by matrix metalloproteinases.
is rarely associated with disease conditions.
is a static structure that serves as a barrier to molecules attempting to cross the cell membrane.
has very similar characteristics throughout the body.

Which one of the following statements is FALSE about laminins?

They are extracellular phospholipids.
They are important in the migration of primordial germ cells.
They influence nerve outgrowth.
They bind to components of the basement membrane.
All of the choices are correct.

Which one of the following statements is FALSE about the basement membrane?

It underlies the inner endothelial lining of blood vessels.
It underlies the epithelial lining of the skin.
It may thicken in long-term diabetics.
It can prevent passage of proteins out of the blood and into the tissues.
It lies in contact with the apical plasma membrane of epithelial cells.

Which one of the following statements about collagen is FALSE?

It is largely produced by fibroblasts, but also by some other cells.
It is always present in the form of fibrils.
More than one type of collagen may be found in a single fiber.
The three-dimensional organization of collagen molecules is correlated with the properties of a particular tissue.
Collagens are very strong and resistant to pulling forces.

Matrix metalloproteinases act MOSTLY as:

buffers.
fibers.
enzymes.
receptors.
markers.

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.
fibronectin is not normally present in the embryo.

Which one of the following disorders is NOT related to abnormalities in collagen formation?

pulmonary fibrosis
cirrhosis of the liver
osteogenesis imperfecta
scurvy
emphysema

Which one of the following statements is FALSE?

The epidermis is composed of epithelial tissue; the dermis is composed of connective tissue.
Epithelial tissue lines the spaces and free surfaces of the body.
The outer surface of the plasma membrane contains receptors that mediate interactions between the cell and its environment.
Cell-surface receptors allow communication between the external environment and the internal environment of the cell.
The epidermis contains a number of distinct fibers that communicate with neighboring closely packed cells.

Interactions between cells and extracellular materials are involved in:

cell growth.
cell migration.
organization of tissues and organs.
cell differentiation.
all of the choices are correct.

Functions of the extracellular matrix do NOT include:

acting as a barrier to the passage of macromolecules.
separating adjacent tissues within an organ.
producing energy.
providing mechanical support.
serving as a substratum for cell migration.

Which one of these molecules is NOT a major component of the extracellular matrix in eukaryotes?

peptidoglycan
collagen
fibronectin
proteoglycan
laminin

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

The secretory and synthetic activities of the cells decrease.
The secretory and synthetic activities of the cells increase.
The cells die.
The cells enunciate.
The secretory and synthetic activities of the cells do not change.

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

hyaluronidase
hyaluronic acid
proteoglycase
fibronectin
laminin

Three-dimensional (3D) cellular structures that resemble organs in both development and organization are called:

organelles
organics
organoids
organs
enginorgans

Which of the following is NOT an example of stem cells?

tissue-specific stem cells from a mature organism
embryonic stem cells
induced pluripotent stem cells
stem cells from adult intestinal crypts
mature skin cells

In recent years, researchers have been able to develop organoids from which of the following tissues?

intestine
stomach
pancreas
optic cup
All of the other choices

Which of the following is a potential application of organoids?

creating model tissues that can be used in studying diseases
testing new drug therapies
growing organoid cultures that can be used for the individualized testing of potential therapeutics
growing organoid cultures that can be used for high-throughput testing of potential therapeutics
All of the other choices.

The addition of a peptide containing an RGD sequence would probably _______ the binding of cultured cells possessing surface receptors for fibronectin to a fibronectin-coated dish.

increase the amount of
inhibit
have no effect on
increase the rate of
both A and D are true.

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 bind to a diverse array of ligands.

Focal adhesions are common in cultured cells and are similar to adhesive contacts in:

dermis to epidermis connections.
muscle cell to tendon connections.
cartilage to bone connections.
bone to ligament connections.
focal adhesions are characteristic only of cells grown in vitro and are not similar to in vivo connections.

Integrins:

are receptors found on the cell surface.
are found on every living cell.
are composed of carbohydrate chains.
bind to molecules on the outside of the cell membrane, but do not bind to molecules on the inside of the cell.
are ubiquitous in the eukaryotic world.

Actin filaments are to focal adhesions as __________ are to hemidesmosomes.

myosin filaments
keratin filaments
microfilaments
integrins
collagen fibrils

________ 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
Calmodulins

Calcium-dependent adhesion is to the cadherins as calcium-independent adhesion is to the:

IgSF proteins.
fibronectins.
integrins.
glycocalyx.
adherins.

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
weak flexible bones

Which one of the following statements is TRUE?

Protein kinases prevent phosphorylation of a target protein.
Protein kinases activate target proteins through physical interaction.
Protein kinases and G proteins are regulatory molecules found within the cytosol.
Integrins are involved in making cell connections, but are not involved in transmembrane signaling.
Transmembrane signaling occurs only in epithelial cells.

Integral membrane proteins that play major roles in cell adhesion include all of the following EXCEPT:

selectins.
certain members of the immunoglobulin superfamily (IgSF).
certain integrins.
cadherins.
collagen.

Possible reasons why metastatic cancer cells are less adhesive include:

these cells produce matrix metalloproteinases that are directly associated with their invadopodia.
reduced levels of E-cadherins.
the ECM acts as a barrier.
these cells lack integrins.
both these cells produce matrix metalloproteinases that are directly associated with their invadopodia and reduced levels of E-cadherins.

Desmosomes are particularly numerous in all tissue environments EXCEPT:

tissues that are subjected to mechanical stress.
hyaline cartilage
the epithelial layer of the uterine cervix.
the skin.
cardiac muscle

When lymphocytes were removed from peripheral lymph nodes, radioactively labeled, and injected back into the body:

they returned to the sites from which they were originally derived.
they died.
they were attacked by immunoglobulins.
they damaged the internal organs.
they were attracted by the lymphocytes in the lymph nodes.

Which of the following can be affected by transmembrane signaling?

survival of a cell
migratory activity of a cell
growth of a cell
differentiation of a cell
All of these can be affected by transmembrane signaling.

Adherens junctions:

are particularly common in cardiac muscle.
form calcium-independent linkages with neighboring cells.
connect the external environment to microtubules of the cytoskeleton.
ensure survival of endothelial cells in the walls of blood vessels.
are common on the basal membrane of epithelial cells.

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 phospholipid 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 cause lysis of neutrophils.

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

They lose water.
They extrude cytoplasm.
They send out projections that make increasingly stable attachments.
Their membranes stiffen.
They make focal assignations.

Mice lacking the gene for claudin-1 are likely to die of:

malformation of the blood-brain barrier.
dehydration.
abnormally low levels of magnesium.
absence of an immune response.
uncontrolled inflammation.

Which one of the following statements is FALSE?

Tight junctions are numerous in epithelial tissue.
Tight junctions contain significant amounts of the proteins occludin and claudin.
Tight junctions help to form the blood-brain barrier.
Tight junctions may be selectively permeable.
Tight junctions are highly permeable to water.

Cells of the heart must contract in synchrony to produce an effective heartbeat. 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 that would be instrumental in accomplishing this task?

gap junctions
tight junctions
desmosome
adherens junctions
plasmodesmata

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
desmosomes, desmotubules

The first researchers to observe flow of ionic currents from one cell directly into another cell were:

Furshpan and Potter.
Kanno and Lowenstein.
Watson and Crick.
Revel and Karnovsky.
Naus and Yamasaki.

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

2
4
6
8
10

Cancer cells:

have increased numbers of gap junctions.
lose their ability to transmit signals across gap junctions.
transmit connexins to neighboring cells through gap junctions.
metastasize to adjacent tissues through gap junctions.
can be treated with chemotherapy through gap junctions.

Cell walls are NOT found in:

bacteria.
algae.
fungi.
animal cells.
terrestrial plants.

The molecules found within a plant cell wall include:

cellulose, pectin, hemicellulose and glycolipids.
cellulose, pectin, hemicellulose and proteins.
lignin, glycogen, cellulose and glycolipids.
proteoglycans, cellulose, hemicellulose, glycolipids.
cellulose, pectin, lignin, collagen.

About how long ago, did a population of algae start to move onto land?

Around 2 billion years ago
Around 1 billion years ago
Around 650 million years ago
Around 450 million years ago
Around 218 million years ago.

What ancient group of organisms is thought to have given rise to the vast diversity of land plants observed on our planet today?

bryophytes
charophycean green algae
cyanobacteria
cryologenous red algae
bassanypherous green algae

What evidence suggests that all land plants are descended from charophycean green algae?

Both groups of organisms have a particular rosette arrangement of cellulose synthase.
Both groups of organisms have a higher percentage of cellulose in their cell walls.
Both groups of organisms have vascular systems.
Both groups of organisms have exactly the same auxiliary photosynthetic pigments.
Both groups of organisms have a particular rosette arrangement of cellulose synthase and a higher percentage of cellulose in their cell walls.

What traits may have been critical for the ability of plants to adapt to life on dry land?

the specific cellulose microfibril structures created by rosette-arranged cellulose synthase complexes
a higher density of cellulose in cell walls
more efficient photosynthetic pigments
decreased turgor pressure
the specific cellulose microfibril structures created by rosette-arranged cellulose synthase complexes and a higher density of cellulose in cell walls

More recent studies have shown that some extant charophycean green algae species produce a number of other cell wall components shared with land plants, including:

mucilage
pectins
chlorophyll a
collagen
cellulose

Some researchers believe that certain cell wall innovations that evolved before the move from water to land helped the first land-dwelling plants to survive. In what ways might these innovations have helped the plants survive?

They may have helped the plants resist environmental stresses.
They may have helped to prevent desiccation.
They may have helped to protect the plants from UV damage.
They may have supplied more light to the plants.
They may have helped the plants resist environmental stresses, prevent desiccation, and protect the plants from UV damage.