chapter 8 Flashcards
primary cell wall
the outermost layer of a plant cell wall made of cellulose fibers and gelatinous polysaccharides that defines the shape of the cell and withstands the turgor pressure of the plasma membrane
pectins
a gelatinous polysaccharide found in the primary cell wall of plant cells, attracts and holds water forming a gel that keeps the cell wall moist
turgor pressure
the outward pressure exerted by the fluid contents of a plant cell against its cell wall
secondary cell wall
the inner layer of a plant cell wall formed by certain cells as they mature, provides support or protection
lignin
a substance found in the secondary cell walls of some plant cells that is exceptionally stiff and strong , most abundant in woody plants
extracellular matrix
a complex meshwork of proteins and polysaccharides secreted by animal cells and in which they are embedded
collagen
a fibrous, pliable cable-like glycoprotein that is a major component of the extracellular matrix of animal cells
integrins
any of a class of cell-surface proteins that bind to fibronectins and other proteins in the extracellular matrix thus holding cells in place
fibronectins
an abundant protein in the extracellular matrix that binds to other ECM components and to integrins in the plasma membrane helps anchor cells in place
metastasis
the spread of cancerous cells from their site of origin to distant sites in the body where they may establish additional tumors
multicellularity
the state of being composed of many cells that adhere to each other and do not all express the same genes with the result of specialized cell functions
tight junction
a type of cell to cell attachment where the plasma membrane of adjacent animal cells are attached, forming a barrier to restrict movement in the space between the cells
desmosomes
a type of cell to cell attachment consisting of cadherin proteins that binds the cytoskeleton of adjacent animal cells together
selective adhesion
the tendency of cells of one tissue type to adhere to other cells of the same type
antibody
an immunoglobulin protein produced by B cells that can bind to a specific part of an antigen tagging it for attack by the immune system
cadherins
any of a class of cell surface proteins involved in cell adhesion and important for coordinating movements of cells during embryological development
plasmodesmata
physical connection between two plants cells consisting of gaps in the cell walls through which the plasma membranes, cytoskeletons, and smooth ER can connect directly
hormones
any of many different signaling molecules that circulate throughout the body in blood and other body fluids and can trigger characteristic responses in distant target cells at very low concentrations
signal receptor
any cellular protein that binds to particular signaling molecule and triggers a response by the cell
signal transduction
the process by which a stimulus outside a cell is amplified and is converted to a response by the cell
G proteins
guanine nucleotide-binding proteins, are a family of proteins that act as molecular switches inside cells, and are involved in transmitting signals from a variety of stimuli outside a cell to its interior.
second messenger
a nonprotein signaling molecule produced or activated inside the cell in response to a stimulus at the cell surface
protein kinases
an enzyme that catalyzes the addition of a phosphate group to another protein, typically activating or inactivating the substrate protein
receptor tyrosine kinases
any of a class of cell surface signal receptors that undergo phosphorylation after binding a signaling molecule. The activated phosphorylated receptor then triggers a signal transduction pathway inside the cell
Ras protein
G protein that is activated by the binding of a signaling molecule to receptor tyrosine kinases and then initiates a phosphorylation cascade
phosphorylation cascade
a series of enzyme-catalyzed phosphorylation reactions commonly used in signal transduction pathways to amplify and convey a signal inward from the plasma membrane
cross-talk
interactions among signaling pathways that modify a cellular response
quorum sensing
cell to cell signaling in bacteria in which cells of the same species communicate via chemical signals. It is often observed that cell activity changes dramatically when the population reaches a threshold size or quorum
biofilms
a hard, polysaccharide rich layer secreted by bacterial cells which allows them to attach to a surface
