Biological Membranes Flashcards
composed primarily of lipids with some associated proteins and carbs
Plasma Membrane (PM)
pass completely through the lipid bilayer
transmembrane proteins
associated w/ only interior or exterior surface pm
embedded proteins
may be bound through electrostatic interactions with the lipid bilayer
membrane associated (peripheral) proteins
proteins that allow cells to recognize each other & contribute to proper cell differentiation and development
Cell Adhesion Molecule (CAM)
allow for direct cell-cell communication & are often found in small bunches together; also called connexons (pores composed of 6 molecules of connexin)
gap junctions
prevent solutes from leaking into the spaces btw cells via a paracellular route
tight junctions
bind adjacent cells by anchoring their cytoskeletons
desmosomes
processes that do not require intracellular energy stores but rather utilize the [ ] gradient to supply the energy for particles to move
passive transport
substrates move down their concentration gradient directly across the membrane
simple diffusion
water will move from a region of lower solute concentration to one of higher solute concentration
osmosis
simple diffusion for molecules that are impermeable to the membrane (large, polar, or charged)
facilitated diffusion
are only open to one side of the CM at any given point
carriers
state in which the carrier is not open to either side of the phospholipid bilayer
occluded state
viable transporters for facilitated diffusion, may be in open or closed conformation
channels
results in the net movement of a solute against its [ ] gradient
active transport
uses ATP or another energy molecule to directly power the transport of molecules across a membrane
Primary Active Transport
uses energy released by one particle’s going down its electrochemical gradient to drive a different particle up its gradient
Secondary Active Transport
when both particles flow the same direction across the membrane
Symport
particles flow in opposite directions
Antiport
occurs when the cell membrane invaginates and engulfs material to bring it into the cell
Endocytosis
endocytosis of fluids and dissolved particles
pinocytosis
ingestion of large solids such as bacteria
phagocytosis
occurs when secretory vesicles fuse with the membrane, releasing material from inside the cell to the extracellular environment
exocytosis
