Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
31 Cards in this Set
- Front
- Back
|
selective permeability
|
it allows some substances to pass i more easily than others
|
|
|
fluid mosaic model
|
the currently accepted model for the arrangement of phospholipids and proteins in the membranes of cells. fluid structure with a "mosaic" of various proteins embedded in or attached to a double layer of phospholipids
|
|
|
integral proteins
|
penetrate the hyrdophobic core of the lipid bilayer.
|
|
|
peripheral proteins
|
not embedded in the lipid bilayer at atll; they are appendages loosely bound to the surface of the membrane, often to exposed parts of integral proteins
|
|
|
concentration gradient
|
the region along which the density of a chemical substance decreases.
|
|
|
passive transport
|
diffusion of a substance across a biological membrane. the cell does not have to expend energy to make it happen.
|
|
|
osmosis
|
the movement of water across cell membrances; or the diffusion of water across a selectively permeable membrane
|
|
|
tonicity
|
the ability of a solution to cause a cell to gain or lose water. depends in part on concentration of solutes that cannot pass membrane, relative to the inside.
|
|
|
isotonic
|
the volume of an amimal cell is stable; no net movement of water across the plasma membrane. iso=same.
|
|
|
hypertonic
|
the cell will lose water to its environment, shrivel and probably die. has more nonpenetrating solutes.
|
|
|
hypotonic
|
the water will enter the cell faster than it leave, and the cell will swell and lyse (burst). has less nonpenetrating solutes
|
|
|
osmoregulation
|
the control of water balance
|
|
|
turgid
|
very firm; healthy state for most plants.
|
|
|
flaccid
|
limp; when a plants cells and surroundings are isotonic, no net tendency for water to enter
|
|
|
facilitated diffusion
|
when many polar molecules and ions empede the lipid bilayer of the membrane diffuse passively with the help of transport proteins that span the membrane.
|
|
|
plasmolysis
|
when a plant cell shrivels and its plasma membrane pulls away from its cell wall. causes plant to wilt and most likely die.
|
|
|
ion channels
|
group of channel proteins function as gated channels
|
|
|
gated channels
|
channels which open or close in response to a stimulus-electrical or chemical
|
|
|
active transport
|
used to pump a solute across a membrane against its gradient that requires work; the cell must expend energy. (membrane traffic)
|
|
|
sodium-potassium pump
|
transport system that works to exchange sodium for potassium across the plasma membrane of animal cells
|
|
|
membrane potential
|
the voltage across a membrane; ranges from -50 to -200 millivolts
|
|
|
electrochemical gradient
|
the combination of forces acting on an ion
|
|
|
electrogenic pump
|
a transport protein that generates voltage across a membrane
|
|
|
proton pump
|
actively transports hydrogen ions out of the cell; main electrogenic pump for bacteria, plants, and fungi.
|
|
|
cotransport
|
a single ATP powered pump that transports a specific solute can indirectly drive the active transport of several other solutes in the mechanism.
|
|
|
exocytosis
|
cell secretes certain biological molecules by thcye fusion of vesicles with the plasma membrane
|
|
|
endocytosis
|
the cell takes in biological molecules and particular matter by forming new vesicles from the plasma membrane
|
|
|
phagocytosis
|
"cellular eating"
|
|
|
pinocytosis
|
"cellular drinking"
|
|
|
ligands
|
any molecules that binds specifically to a receptor site of another molecule
|
|
|
receptor mediated endocytosis
|
used in human cells to take cholesterol for use in the synthesis of membranes and other steroids
|
