Lipids

• a family of biomolecules that have the common property of being soluble in organic solvents but not in water.
• typically the lipid content of a plant cell can be extracted using an organic solvent such as ether, chloroform, or acetone

fatty acids+ long chain of alcohols

fatty acids+ glycerol

• melting pt- determined by length of the chain & degree of unsaturation
• saturated- higher mp than unsaturated with same number of carbon atoms
• more double bonds- lower mp ignoring # of carbons
• solubility- low in water

glycerol+ fatty acid

alcohol+ fatty acid+ a third component

these undergo hydrolytic cleavage into two or more considerably smaller compounds in the presence of an acid, a base, or a digestive enzyme. All of these contain at least one ester group

these don't undergo hydrolytic cleavage b/c they don't contain an ester or amide, phosphate, or acetal group

• cell membrane structure
• energy storage
• hormones and vitamins

• long chain monocarboxylic acid
• size range C₁₂-C₁₄
• always and even number of carbons

• saturated- no double bonds
• unsaturated- one or more double bonds

• 18 tells number of C atoms
• 3 tells number of double bonds

the delta sign after the number of double bonds indicates the placement of the double bonds

monounsaturated fatty acids have 1 double bond in the carbon chain

polyunsaturated fatty acid have 2 or more double bonds

one part of the molecule is hydrophobic and another part is hydrophilic

• chemically fats and oils are both esters
• the alcohol portion is always derived from glycerol and the acid portion is furnished by the fatty acid
• B/c glycerol has 3 OH groups, a single molecule of glycerol can be bonded to 3 different acid molecules

• fats and oils
• a compound formed by the esterfication of three fatty acids to glycerol

• an omega- 6 fatty acid
• this means that the end most double bond is located 6 carbons from the methyl end of the chain
• CH₃(CH₂)₄(CH=CHCH₂)₂(CH₂)₆COOH

an omega- 3 fatty acid where the end most carbon atom having the double bond is 3 carbons from the methyl end

a synthetic polyester of sucrose and fatty acids passes through the digestive tract unabsorbed

• fats- soild at room temp
• oils- liquid at room temp
• waxes are solid- ester of a saturated fatty acid and a long chain alcohol containing from 14-30 carbons- serves as a protective coating in feathers

• esters of fatty acid and long chain alcohols
• water insoluble and not easily hydrolyzed

• ester of glycerol and a fatty acid.
• principal function is energy storage- fat
• diagram in note!

RCOOH+ROH--> RC(=O)OR+H₂O

• RC-C(=O)-OR+ H₂O-->R-C-OH + ROH
• important for fat and oil digestion

• RCOOH+NaOH-->RCOO^-Na⁺+H₂O
• the commerical production of the salt of fatty acids (soap)

• they can undergo the same reactions
• will also undergo addition
• most common addition is hydrogenation

• not all of the double bonds are converted to single bonds
• convert the oil into a solid

• decreases the degree of unsaturation, used to make margarines from oils
• now a health concern about the hydrogenation of food products.
• the problem is that during hydrogenation some of the cis-bonds are converted to trans

• hydrolysis-->glycerol+ 3 fatty acids
• saponification: 3 fatty acids+glycerol--> 3 fatty acid salts + 3 water
• esterification--> triacylglyerol + 3 water
• hydrogenation--> reduces the degree of PUFAs

• the C-C double bonds present in the fatty acid residues of a triacygylcerol are subject to oxidation with oxygen from the air as teh oxidizing agent
• producing both aldehyde and carboxylic acid products
• comerically prepared foods containing fats and oils nearly always contain antioxidants- substances that are more easily oxidized than the food

• oxygenated C₂₀ fatty acids that function as a messenger
• these are "hormone like" molecules rather than true hormones b/c they are not transported in the blood stream to their site of action
• unsaturated
• some are essentail fatty acids

• 1.inflammatory response
• 2.production of paon and fever
• 3.regulation of blood pressure
• 4.induciton of blood clotting
• 5.control of reproduction functions
• 6.regulation of the sleep/ wake cycle

• all are dervied from arachidoric acid a twenty carbon fatty acid derivation that contains a cyclopentane ring and oxygen containing functional group
• most of these are synthesized from arachidonic acid by a ring closer at C 8 & 12
• the enzyme catalyzing this is called cycloxygenase (COX)

catalyzes the normal physiological function

responsibly for the production of prostaglands

prostaglandins stimulate contractions in the reproductive system

• prostoglandins will:
• inhibit the secretion of hydrocholoric acid in the stomach
• increase secration of mucus layer
• protects mucose from acid invasion

block the oxidation of an achidonic acid to form the various classes of eicosanoids (block COX-2)

produced by WBC's in lungs

• produced by platelets in blood
• stimulates constriction of blood vessels
• Aggreation of platelets

broad class of compounds that all have the same base structure. a nonsaponifiable lipid

• most abundant steroid in the human body
• principal membrane lipid for fluidity
• insoluble in the aqueous medium of the blood

in order for it to be transported from the liver where it is synthesized, to the tissues, cholesterol combines w/ phospholipids & proteins to form small water soluble spherical particles called lipoproteins

• LDL supply more cholesterol than is needed, LDLs deposit cholesterol in the wall of arteries forming plaque
• results in:
• increased bp from: narrowing of arteries, reduced ability to stretch
• clot formation leading to: MI, stroke

need for healthy cell membranes and it serves as teh starting material for the synthesis of all other steroids and vit. D

low density lipoproteins transport chloesterol from the liver to the tissue

high density lipoproteins transport cholesterol from the tissue bakc to the liver

• emulsifying agents that make dietary lipids soluble in the aqueous environment of the digestive tract
• these salts are released ino the intestine from the gallbladder

• bile, a fluid secreted by the liver, stored in hte gallbladder, and released into the small intestine during digestion
• bile salts are cholesterol oxidation products

control reproduction and secondary sex hormones

• synthesized in the ovaries and adrenal cortex- the female sex hormone
• responsible for secondary sex characteristics, onset of puberty, regulation of the menstrual cycle, stimulate the development of the mammary glands

• synthesized in the testes
• responsible for the male scondary sex characteristics

• synthesized in the ovaries and the placenta
• prepare the lining of the uterus for implantation of the fertilized ovum

=)