LIPIDS

LIPIDSChem 161 Sat 8:30-11:301LIPIDSCompounds with preponderance of nonpolar groupsLimited solubility in waterSoluble in organic solvents, e.g. acetone and chloroformFATTY ACIDS

contains a COOH group

contains both polar (-COOH) and nonpolar (hydrocarbon) groups

amphipathicSATURATED FATTY ACIDS

UNSATURATED FATTY ACIDS

Exists in cis form

What happens to the melting point of the acids as the length of the carbon chain grows?Why?Which of the fatty acids are monounsaturated? Polyunsaturated?For monounsaturated FAs, do we observe the same relationship with the length of the chain and their melting points?

What pattern can be observed on the PUFAs melting point,whose length of carbon chain is the same?

What is the effect of the double bonds on the intermolecular force of these PUFAs?ESSENTIAL FATTY ACIDSNeeded in the human body that must be obtained from dietary sources because it cannot be synthesized within the body, in adequate amounts

ESSENTIAL FATTY ACIDS

Why are we talking about fatty acids?

TRIACYLGLYCEROLSStorage lipidsAlso known as fats/oils, triglycerides

TRIACYLGLYCEROLSMain reserve of energy (9 kcal/g), as compared to carbohydrates and proteins (4 kcal/g)

Stored in adipose tissues

TRIACYLGLYCEROLS

Simple triacylglycerolTRIACYLGLYCEROLS

Mixed triacylglycerolFats and oils? What is the difference?

FatOilGenerally from animalsGenerally from plantsWhat causes the difference in their physical states?

FatOil

REACTIONS Hydrolysis

REACTIONS Hydrogenation

REACTIONSOxidation

Antioxidants are usually added: BHT (butylated hydroxytoluene) and BHA butylated hydroxyanisole

PHOSPHOACYLGLYCEROLComponent of membranes

PHOSPHOACYLGLYCEROLBasis of classification

PHOSPHOACYLGLYCEROLBasis of classification

WAXESEsters from long chain alcohol (fatty alcohol) and long chain carboxylic acid (fatty acid)Protective coating

Component of carnauba waxWAXESEsters from long chain alcohol (fatty alcohol) and long chain carboxylic acid (fatty acid)Protective coating

Component of spermacetiSperm Whale

SPHINGOLIPIDS

Found in the nervous systemSPHINGOLIPIDSFound in the nervous system

Serves as coating of the myelin sheathGLYCOLIPID

Serves as markers for cellular recognitionGLYCOLIPID

Found in nerve tissuesSTEROIDS

What is common to all these steroids?STEROIDSPresence of this ring system

STEROIDSPresence of this ring system

Cholesterol

Component of membrane and starting material for other steroidal compoundsTransported by HDL and LDLBILE ACIDSFunctions as emulsifying agents

SEX HORMONES

ADRENOCORTICOID HORMONESProduced by the adrenal glands

BIOLOGICAL MEMBRANESMade up mostly of the lipid bilayers

Made up of phosphoglycerides, glycolipids, cholesterol (phytosterols)BIOLOGICAL MEMBRANESMade up mostly of the lipid bilayersMade up of phosphoglycerides, glycolipids, cholesterol (phytosterols)

BIOLOGICAL MEMBRANES

BIOLOGICAL MEMBRANES

Fatty acid profile of the membrane determines its fluidityBIOLOGICAL MEMBRANESPresence of cholesterol decreases the fluidity of the membrane

BIOLOGICAL MEMBRANESProteins are also found in the lipid bilayerIntegral and peripheral proteinFunctions as transport and receptor

BIOLOGICAL MEMBRANESProteins are also found in the lipid bilayerIntegral and peripheral proteinFunctions: transport, receptor, catalysis

FLUID MOSAIC MODEL

Accepted model of the biological membraneTRANSPORTTwo kinds based on use of energyPassive transport substance moves from higher concentration to lower concentration

b. Active transport substance moves against a concentration gradientPASSIVE TRANSPORTSimple diffusion-commonly seen in gases

Facilitated diffusion-assisted by protein carriers

ACTIVE TRANSPORT

BIOLOGICAL MEMBRANESProteins are also found in the lipid bilayerIntegral and peripheral proteinFunctions: transport, receptor, catalysis

RECEPTOR

EICOSANOIDSDerived from arachidonic acid

Prostaglandins, leukotrienes, thromboxanes

PROSTAGLANDINS

Induction of inflammation, control of blood pressure, stimulation of smooth muscle contraction, inhibit platelet aggregationLEUKOTRIENES

Play a role in smooth muscle constriction, like in asthma attacks

THROMBOXANES

induce platelet aggregation and smooth muscle contraction

What are the functions of lipids? A polar bear asked me.

FAT-SOLUBLE VITAMINS

VITAMIN A

VITAMIN A

An aldehydeVITAMIN A