chapter 20 key terms cellular communities

cell junction in which the cytoplasmic face is attached to actin filaments.

describes the tip of a cell, structure, or organ. the apical surface of an epithelial cell is the exposed free suface (opposite to the basal surface).

situated near the base. the basal surface of a cell is opposite the apical surface.

thin mat of extracellular matrix that separates epithelial sheets, and many types of cells, such as muscle cells or fat cells, from connective tissue. sometimes called a basement membrane.

a member of a family of proteins that mediates Ca2+ - dependant cell-cell adhesion in animal tissues.

disease caused by abnormal and uncontrolled cell division resulting in localized growths, or tumors, which may spread throughout the body.

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

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.

fibrous protein rich in glycine and proline that is a major component of the extracellular matrix and connective tissues. exisits in many forms: type I, the most common, is found in skin, tendon, and bone; type II is found in cartilage; type IV is present in basal laminae; and so on.

tissues such as bone, tendons, and the dermis of the skin, in which extracellular matrix is plentiful and carries the mechanical load.

specialized cell-cell juntion, usually formed between two epithelial cells, characterized by dense plaques of protein into which intermediate filaments in the two adjoining cells are inserted.

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

an undifferentiated cell type derived from the inner cell mass of an early mammalian embryo. embryonic stem cells can be maintained indefinately as a proliferating cell population (cell line) in culture, but remain capable of differentiating, when placed in an appropriate environment, to give any of the specialized cell types in the adult body.

sheets of cells covering an external surface or lining an internal body cavity.

common cell type found in connective tissue that secretes an extracellular matrix rich in collagen and other extracellular matrix macromolecules. migrates and proliferates readily in wounded tissue and in tissue culture.

extracellular matrix protein that binds to integrins on cell surfaces, helping cells to adhere to the matrix.

communicating cell-cell junction that allows ions and small molecules to pass from the cytoplasm of one cell to the cytoplasm of the next.

increased mutation rate seen, for example, in cancer cells, resulting from the presence of mutations that interfere with the accurate replication and maintenance of the genome.

family of high-molecular-weight polysaccharides containing amino sugars; found as protective coats around animal cells.

specialized anchoring cell junction between an epithelial cell and the underlying basal lamina.

somatic cell reprogrammed into an embryonic stem-cell-like state by artificially introducing a particular set of genes.

family of transmembrane proteins present on cell surfaces that enable cells to adhere to each other and to the extracellular matrix, being also involved in cell signaling.

the spreading of cancer cells throughout body from the inital site of the tumor.

any abnormally activated gene that can make a cell cancerous. typically a mutant form of a normal gene (proto-oncogene) involved in the control of cell growth or division.

cell-cell junction in plants in which a channel of cytoplasm lined by membrane connects two adjacent cells through a small pore in their cell walls.

molecule consisting of one or more glycosaminoglycan chains attached to a core protein.

relatively undifferentiated cell that can continue dividing indefinately, throwing off daughter cells that undergo terminal differentiation into particular cell types.

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.

organized mass of cells with a specific function that forms a distinctive part of a plant or animal.

a gene that in a normal tissue cell inhibits progress through the cell cycle. Loss or inactivation of both copies of such a gene from a diplois cell can cause it to divide as a cancer cell.

member of the Wnt family of extracellular signal proteins with many roles in development, inclusing the maintenance of stem cells in a proliferative state.