Lipids pt.2

advatages of fats over polysaccharides

• carry out more energy

• carry less water

• provids long0term (months) energy needs

Waxes

esthers of long chain saturated and unsaturated fatty acids with long chain alcohols

insoluble w/high melting pounts

wax functions

• storage of metabolic fuel in plankton

• protection and pliability for hair and skin in vertebrates

• waterproofing feathers

• protection from evaporation in tropical plants

• lotions, ointments, and polishes

Structual lipids in membranes (polar)

• polar heads and nonpolar tails

• diversity can come from

  • modifying backbones

  • changing the fatty acids

  • modifying head groups

• The properties of head groups determine the surface properties of membranes

Structual lipids in membranes (polar): diversity

• diff organisms have different mebrane lipid head group compositions

• diff tissues have different mebrane lipid head group compositions

Glycerophospholipids

• primary constituents of cell membranes

• two fatty acids form ester linkages w/ 1st and 2nd hydroxyl groups of L-glycerol-3-phosphate

• head group is charged at physiological pH

General structure of glycerophospholipids

• unsaturated fatty acids are commonly found connected to C2

• the highly polar phjosphate group may be further esterified by an alcohol (called head groups)

Exampkes of ohospholipds

• phophatidic acid

• phosphatidylcholine (choline)

• phosphatidylseine (serine)

• phosphatidylglycerol (glycerol)

• phosphartdylinositol4,5-biphosphate (mayo-inositol4,5-biphospate)

• cardiolipin (phosphatidylglycerol)

phosphatidylcholine

• major component of most eukaryotic cell membranes (prokaryotes like E coli don’t)

Ether Lipids: plasmogen

• vinyl ether analog of phosphatidylethanolamine

• common in vetebrate heart tissue in some protozoa and bacteria

Ether Lipids: platelets-activating factor

• Aliphatic ether analog of phosphatidylcholine

• Acetic acid has esterified position C2

• 1st signaling lipid IDed

• stimulated blood platelet aggregation

• mediates inflammation

Sphingolipids

back bone is not glycerol

• it is a long chain amino alcohol sphingosine

sphingolipid composition

a fatty acid is joing to sphingosine via an amide linkage (not ester like most lipids)

polar head group is connected by a glycosidic or phosphodiester linkage

sugar containing ones are on the outer face of the membrane

sphingomyelin

• ceraminde (sphingosine + aminde-linked fatty acid) + phosphocholine attached to alcohol

• abundant in myelin sheaththat sounds nerve cells