Chapter 7 Flashcards
amiphipathic molecule
both water loving (hydrophillic) and water fearing (hydrophobic) regions
fluid mosaic model
membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids
integral proteins
penetrate the hydrophobic interior of the lipid bilayer
transmembrane proteins
spam the membrane
peripheral proteins
not embedded in the lipid bilayer at all; loosely bound to the surface of the membrane
selective permeability
allows some substances to cross more easily than others
diffusion
the movement of particles of any substance so that they spread out into the available space
concentration gradient
region along which the density of a chemical substance increases or decreases
passive transport
diffusion of a substance across a biological membrane
osmosis
diffusion of free water across a selectively permeable membrane, whether artificial or cellular
tonicity
the ability of a surrounding solution to cause a cell to gain or lose water
isotonic
iso (same; no net movement of water across the plasma membrane
hypertonic
hyper (more water)
hypotonic
hypo (less water)
osmoregulation
the control of solute concentrations and water balance
turgid
very firm
flaccid
limp
plasmolysis
as the plant cell shrivels, its plasma membrane pulls away from the cell wall at multiple places (can lead to plant death)
facilitated diffusion
molecules and ions blocked by the lipid bilayer of the membrane diffuse passively with the help of transport proteins that span the membrane
electrochemical gradient
combinations of forces acting on an ion
cotransport
a transport protein can couple the down hill diffusion of the solute to the uphill transport of a second substance against its own concentration gradient
endocytosis
cell takes in molecules and particulate matter by forming new vesicles from the plasma membrane
