bch 351 lipids, fatty acids (triacylglycerols & phospholipids) & cholesterol

lipid fxns

structural components of membranes

barriers w/in cells

E storage molecules

vitamins

chemical signals & recognition

fatty acids structure

long aliphatic (NP) hydrocarbon tail attached to polar head

polar head group pKA = 4.5-5.0 & is anion at pH 7

sat FAs

no double bonds

solid @ room temp

unsat FAs

has double bonds

liquid @ room temp (oil)

most naturally occurring FAs have ___ double bond configuration

cis

the longer the chain of a FA, the ___ the melting temp

higher

the more double bonds in a FA chain, the __ the melting temp

lower

monounsat FAs

one double bond

polyunsat FAs

multiple double bonds

greek letter for terminal C

w

omega

cis FAs

bent shape (kink)

more difficult for fats to stack upon each other since H’s on same side, so they will be mostly liquid form

trans FAs

straight shape

since H’s on opposite sides, its easier for the molecules to stack upon each other, so they’re mostly found in solid form & have higher melting point

triacylglycerol

3 fatty acyl chains joined by ester bonds to glycerol (3 C alcohol)

very hydrophobic

liquid or solid depending on length of FA chains & # of double bonds

TAGs energy storage

fats & oils usually found as TAGs

used for long term E storage in adipocytes under skin & abdomen

glycerophospholipids

glycerol w/ 2 acyl chains & phosphate

R1 usually sat FA

R2 usually unsat FA

form membranes & bilayers

micelles

spherical, single lipid layer

soluble in water

hydrophilic head

hydrophobic interior

glycerophospholipid - ethanolamine

phosphate - O - CH2-CH2-NH3+

eth = 2 C

amine = NH3+

glycerophospholipid - serine

phosphate - O - CH2-CH(COO-)-NH3+

glycerophospholipid - choline

phosphate - O - CH2-CH2-N+(CH3)3

3 methyl groups

phospholipases

hydrolyze phospholipids @ specific ester bonds

release AAs

plasmalogens

class of lipid

vinyl ether link (-C=C-)

important for stability & organization of lipid rafts - memb regions w/ high conc of proteins

sphingolipids

class of lipid

built on amino alcohol sphingosine instead of glycerol

enriched in CNS

participate in tissue development, cell recognition & adhesion, receptors for toxins

ceramides

FA linked to NH2 w/ amide bond (-N-CO-R)

important in skin

cholesterol

membrane lipid

hydrophobic, ABCD rings, rigid

cholesterol is a precursor to

steroids

lipoprotein particles

have phospholipid/protein coat that carries lipids

low density lipoprotein (LDL)

transport cholesterol from liver to peripheral tissues

apo B-100 protein targets LDL to tissue

“bad cholesterol”

high density lipoprotein (HDL)

transport cholesterol from blood to liver to be destroyed

scavenges

“good cholesterol”

chylomicrons (lipoprotein)

transport TAGs from intestines to tissues

cholesterol: memb fluidity has an __ relationship w/ temperature

inverse

at high temps, cholesterol will ___ memb fluidity

decrease

at low temps, cholesterol will ___ memb fluidity

increase