Cell Membrane Components

phospholipid structure

glycerol, phosphate, 2 fatty acid tails

cholesterol structure

polar OH head, ring structure, hydrocarbon tail

cholesterol comes from

animals

cell recognition + cell signaling, NO TRANSPORT

glycoprotein

cell recognition, contributes to membrane stability, NO TRANSPORT

glycolipid

allows facilitated diffusion of substances across membrane (passive transport)

protein channel

loosely attached, involved in signal transduction + cytoskeletal anchoring, NO TRANSPORT

peripheral membrane protein

spans across membrane, facilitated diffusion OR active transport

integral membrane protein

found in membranes, hormones, sebaceous glands, ear canal, includes triglycerides, phospholipids, steroids, waxes.

lipids

lipids with choline as head group, mostly in outer membrane layer (e.g. phosphatidylcholine, sphingomyelin).

choline class

has hydrophobic + hydrophilic

amphipathic

most common phospholipid, has choline R group, fatty acid saturation varies

phosphatidylcholine

double bonds in

unsaturated

the synthetic arrangement of phospholipids. has pocket for drug delivery

liposome

naturally forming lipid structure. NOT a bilayer, NO lipid pocket

micelle

membrane fluidity: lipids can

rotate, flex, diffuse laterally, RARELY flip flip (transverse diffusion)

decrease membrane fluidity

saturated phospholipids

main site of lipid synthesis

ER

modifies + sorts lipids for membrane stability

golgi

strongly attached; embedded within lipid bilayer - includes TRANSMEMBRANE + MONOLAYER ASSOCIATED types)

integral membrane proteins

loosely attached to membrane surface, NOT embedded

peripheral membrane proteins

covalently attached to lipids, embedded similarly to integral proteins

lipid-associated proteins

nonpolar external surface, polar H-bonds are internal —> allows interaction with hydrophobic lipid tails

alpha helix

hydrophobic outside, hydrophilic inside, can form pores/channels.

beta-barrel/rolled beta sheet

roles of membrane proteins

transport, anchoring, receptors (ligand binding —> signal transduction), enzymes

alpha helices, beta sheets, barrels define whether protein becomes a pore, channel, or receptor

protein folding importance

proteins are ________ distributed throughout the membrane, and some are restricted to specific regions

asymmetrically

always extracellular, protect protein from damage, retain water for lubrication, prevent unwanted cell-cell adhesion

membrane carbohydrates

type of integral protein that fully spans the membrane

transmembrane proteins

integral protein embedded in only one leaflet of the membrane

monolayer-associated proteins

lipid-associated proteins covalently attached to membrane lipids

lipid-linked proteins

peripheral proteins bound to other membrane proteins rather than the membrane itself

protein-attached proteins