Chapter 20

Question 1

adherens junction

Answer 1

Cell junction that helps hold together epithelial cells in a
sheet of epithelium; actin filaments inside the cell attach to
its cytoplasmic face.

Question 2

apical

Answer 2

Describes the top or the tip of a cell, structure, or organ; in
an epithelial cell, for example, this surface is opposite the
base, or basal surface.

Question 3

basal

Answer 3

Situated near the base; opposite of apical

Question 4

basal lamina

Answer 4

Thin mat of extracellular matrix, secreted by epithelial cells,
upon which these cells sit.

Question 5

cadherin

Answer 5

Disease caused by abnormal and uncontrolled cell
proliferation, followed by invasion and colonization of body
sites normally reserved for other cells.

Question 6

cancer

Answer 6

Disease caused by abnormal and uncontrolled cell
proliferation, followed by invasion and colonization of body
sites normally reserved for other cells.

Question 7

cell junction

Answer 7

Specialized region of connection between two cells or

between a cell and the extracellular matrix.

Question 8

cell wall

Answer 8

Mechanically strong fibrous layer deposited outside the
plasma membrane of some cells. Prominent in most plants,
bacteria, algae, and fungi, but not present in most animal
cells

Question 9

cellulose micropibril

Answer 9

Long, thin polysaccharide fiber that helps strengthen plant

cell walls.

Question 10

collagen

Answer 10

Triple-stranded, fibrous protein that is a major component
of the extracellular matrix and connective tissues; it is the
main protein in animal tissues, and different forms can be
found in skin, tendon, bone, cartilage, and blood vessels.

Question 11

connective tissue

Answer 11

Tissues such as bone, tendons, and the dermis of the skin,
in which extracellular matrix makes up the bulk of the
tissue and carries the mechanical load.

Question 12

desmosome

Answer 12

Specialized cell–cell junction, usually
formed between two epithelial cells, that
serves to connect the ropelike keratin
filaments of the adjoining cells, providing
tensile strength.

Question 13

differentiated cell

Answer 13

Cell that has undergone a coordinated change in gene

expression, enabling it to perform a specialized function.

Question 14

embryonic stem cell

Answer 14

An undifferentiated cell type derived from the inner cell
mass of an early mammalian embryo and capable of
differentiating to give rise to any of the specialized cell
types in the adult body

Question 15

epithelium

Answer 15

Sheet of cells covering an external surface or lining an

internal body cavity.

Question 16

extracellular matrix

Answer 16

Complex network of polysaccharides (such as
glycosaminoglycans or cellulose) and proteins (such as
collagen) secreted by cells. A structural component of tissues
that also influences their development and physiology.

Question 17

fibroblast

Answer 17

Cell type that produces the collagen-rich extracellular matrix
in connective tissues such as skin and tendon. Proliferates
readily in wounded tissue and in tissue culture.

Question 18

fibronection

Answer 18

Extracellular matrix protein that helps cells attach to the
matrix by acting as a “linker” that binds to a cell-surface
integrin molecule on one end and to a matrix component,
such as collagen, on the other.

Question 19

gap junction

Answer 19

In animal tissues, specialized 
connection between juxtaposed 
cells through which ions and small 
molecules can pass from one cell to 
the other.

Question 20

genetic instability

Answer 20

An increased rate of mutation often caused by defects
in the systems that govern the accurate replication and
maintenance of the genome; the resulting mutations
sometimes drive the evolution of cancer.

Question 21

glycosaminoglycan (GAG)

Answer 21

Polysaccharide chain that can form a gel that acts as a
“space filler” in the extracellular matrix of connective
tissues; helps animal tissues resist compression.

Question 22

hemidesmosome

Answer 22

Structure that anchors epithelial cells to the basal lamina

beneath them.

Question 23

induced pluripotent stem cell

Answer 23

Somatic cell that has been reprogrammed to resemble
and behave like a pluripotent embryonic stem (ES) cell
through the artificial introduction of a set of genes encoding
particular transcription regulators.

Question 24

integrin

Answer 24

One of a family of transmembrane proteins present on cell
surfaces that enable cells to make and break attachments
to the extracellular matrix, allowing them to crawl through
a tissue.

Question 25

metastisis

Answer 25

The spread of cancer cells from the initial site of the tumor
to form secondary tumors at other sites in the body.

Question 26

oncogene

Answer 26

A gene that, when activated, can potentially make a cell

cancerous. Typically a mutant form of a normal gene (protooncogene) involved in the control of cell growth or division.

Question 27

organoid

Answer 27

Capable of giving rise to any type of cell or tissue.

Question 28

plasmodesma

Answer 28

Capable of giving rise to any type of cell or tissue.

Question 29

pluripotent

Answer 29

Capable of giving rise to any type of cell or tissue.

Question 30

proteoglycan

Answer 30

Molecule consisting of one or more glycosaminoglycan
chains attached to a core protein; these aggregates can
form gels that regulate the passage of molecules through
the extracellular medium and guide cell migration.

Question 31

proto-oncogene

Answer 31

Gene that when mutated or overexpressed can transform a

normal cell into a cancerous one

Question 32

stem cell

Answer 32

Relatively undifferentiated, self-renewing cell that produces
daughter cells that can either differentiate into more
specialized cell types or can retain the developmental
potential of the parent cell.

Question 33

tight junction

Answer 33

Cell–cell junction that seals adjacent epithelial cells together,
preventing the passage of most dissolved molecules from
one side of the epithelial sheet to the other.

Question 34

tissue

Answer 34

Cooperative assembly of cells and matrix woven together
to form a distinctive multicellular fabric with a specific
function.

Question 35

tumor supressor gene

Answer 35

A gene that in a normal tissue cell inhibits cancerous
behavior. Loss or inactivation of both copies of such a gene
from a diploid cell can cause it to behave as a cancer cell.

Question 36

Wnt protein

Answer 36

Member of a family of extracellular signal molecules that
regulates cell proliferation and migration during embryonic
development and that maintains stem cells in a proliferative
state.