Chapter 20 Key Terms

Question 1

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

Answer 1

Adherens junction

Question 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.

Answer 2

Apical

Question 3

Situated near the base; opposite of apical.

Answer 3

Basal

Question 4

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

Answer 4

Basal lamina

Question 5

A member of a family of Ca+2 dependent proteins that mediates the attachment of one cell to another in animal tissues.

Answer 5

Cadherin

Question 6

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

Answer 6

Cancer

Question 7

Specialized region of connection between two cells or between a cell and the extracellular matrix.

Answer 7

Cell junction

Question 8

Mechanically strong fibrous layer deposited by a cell outside its plasma membrane. Prominent in most plants, bacteria, algae, and fungi, but not present in most animal cells.

Answer 8

Cell wall

Question 9

Long, thin strand of cellulose that helps strengthen plant cell walls.

Answer 9

Cellulose microfibril

Question 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.

Answer 10

Collagen

Question 11

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

Answer 11

Connective tissue

Question 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.

Answer 12

Desmosomes

Question 13

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.

Answer 13

Embryonic stem (ES) cell

Question 14

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.

Answer 14

Extracellular matrix

Question 15

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.

Answer 15

Fibroblast

Question 16

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

Answer 16

Gap junction

Question 17

Structure that anchors epithelial cells to the basal lamina beneath them.

Answer 17

Hemidesmosome

Question 18

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.

Answer 18

Integrin

Question 19

Cell-cell junction that connects one plant cell to the next; consits of a channel of cytoplasm lined by membrane.

Answer 19

Plasmodesma (plural plasmodesmata)

Question 20

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.

Answer 20

Tight junction

Question 21

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

Answer 21

Tissue

Question 22

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.

Answer 22

Fibronectin

Question 23

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.

Answer 23

Genetic instability

Question 24

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

Answer 24

Glycosaminoglycan (GAG)

Question 25

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

Answer 25

Induced pluripotent stem cell (iPS)

Question 26

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

Answer 26

Metastasis

Question 27

A gene, that when activated, can potentially make a cell cancerous. Typically a mutant form of a normal gene (proto-oncogene) is involved in the control of cell growth or division.

Answer 27

Oncogene

Question 28

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

Answer 28

Pluripotent

Question 29

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 ECM and guide cell migration.

Answer 29

Proteoglycan

Question 30

Gene that when mutated or overexpressed can transform a normal cell into a cancerous one.

Answer 30

Proto-oncogene

Question 31

The artificial production of genetically identical copie sof animal by, for example, the transplantation of a somatic cell nucleus into an enucleated fertilized egg.

Answer 31

Reproductive cloning

Question 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.

Answer 32

Stem cell

Question 33

Procedure that uses nuclear transplantation to generate cells for tissue repair and other such purposes, as opposed to producing whole multicellular individuals.

Answer 33

Therapeutic cloning

Question 34

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.

Answer 34

Tumor suppressor gene

Question 35

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.

Answer 35

Wnt protein