1. Types of lipids + FA
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Lipids are characterized by their _______ sensation and ___________ properties when isolated
fatty sensation and lubricant properties
solubility of lipids vs insolubility of lipids
• soluble in nonpolar organic solvents (hexane, chloroform, ether) • insoluble in water
3 major classes of lipids + what?
• simple lipids: FA esterified to alcohol • compound lipids: conjugated to non-lipid moiety • derived lipids: derived in living systems from simple or compound lipids
structure of glycerol
3 carbon chain with OH on each carbon + H to fill all 4 of carbon’s bonds
Triacylglyceride structure + type of bond?
3 FA esterified to glycerol - ester linkage
Are the R groups of FA in triacylglycerol the same?
no. short of long chain with carboxyl group at one end
triglycerides account for ___% of extractable lipid material present in biological systems
90%
difference between oil and fat?
• oil: liquid at room temp • fat: solid at room temp
Melting point: pure TG vs fats/lipids
• pure TG: sharp melting point • fats: solid fat content decreases over a broad temperature range –> reflects mixture of TG
short or long FA chain will melt faster?
short chain
what are waxes?
FA esterified to a fatty alcohol (long chain alcohol)
example of liquid and solid wax
• liquid: jojoba oil • solid: beeswax
Biosynthesis of wax: 2 steps + enzymes
• FA bound to Coenzyme A –> FA reductase catalyzes reduction of FA to fatty alcohol (carboxylic acid to alcohol) • Fatty alcohol + FA bound to CoA (different than first one) –> Wax synthase –> makes wax ester
waxes have limited application for food use –> 2 examples
• sealing agents (cheese) • polishing agents (apples)
Jojoba oil –> what? found where? used in what? + also considered as a potential _________ (because not __________ readily) food ingredient giving a __________
• liquid wax • obtained from seeds of desert shrub native to southwestern US and norther Mexico • cosmetics • low calorie (bc not digested readily) • fatty sensation
True wax vs other compounds in wax category (examples)
true wax: FA esterified to a simple fatty alcohol - other wax category: FA esterified to complex alcohols –> cholesterol and retinol
Cholesterol and retinol –> present in what degree of quantity? + important bc they are ?
• mg and micrograms • bc they are biologically active
Cholesterol structure? vs cholesteryl ester (wax)
OH + 4 rings ish + alkyl chain vs wax: R-C(double bond O)-O-4 rings ish + alkyl chain
retinol structure? vs vitamin A ester (wax) structure
Retinol: hexane ish + alkyl chain with conjugated double bonds + OH wax: hexane ish + alkyl chain + CH2O-C(double bond O)-R
what are compound lipids?
A category of lipids made up of a simple lipid (generally TG) conjugated to a non-lipid molecule
Compound lipids usually separated into 3 categories:
• Phospholipids • Glycolipids/sphingolipids • Lipoproteins
What are phospholipids?
TG with one of FA replaced with phosphoric acid or phosphoric acid derivative
When the non-lipid moiety is a phosphoric acid instead, the phospholipid is called ? Structure?
phosphatidic acid Glycerol + 2 FA + O-P(double bonded O)(-O minus)-OH
Structure of - phosphatidylethanolamine - phosphatidylcholine - phosphatidylserine - phosphatidylinositol
Glycerol + 2 FA + O-P(double bonded O)(-O minus)-X - ethanolamine: X = O-CH2-CH2-NH2 - choline: X = O-CH2-CH2-N+(CH2)3 –> emulsifier! - serine: X = O-CH2-CH(NH2)-COOH - inositol: hexane with OH on each carbone