Lipids Part 1 Flashcards
Lipids
• 4 main groups
(Saturated and Unsaturated)
(Glycerol-containing Lipids)
(Sphingolipids,Steroids,Wax)
(Lipoproteins)
– Fatty Acids
– Glycerides
– Nonglyceride Lipids
– Complex Lipids
Energy Source
– When oxidized, each gram of fat releases______ of energy, or more than twice the energy released by oxidation of a gram of carbohydrate
9 kcal
Energy Storage
– In the form of ____in adipocytes
triglycerides (TAG)
Cell Membrane Structural Components
(3) make up the basic structure of all cell membranes
– Phosphoglycerides, sphingolipids, and steroids
BIOLOGICAL FUNCTIONS OF LIPIDS
• Hormones –_____ Hormones
• Vitamins – Lipid-soluble vitamins
• Vitamin Absorption – Dietary fat serves as a____ of the lipid-soluble vitamins
• Protection – fats as
• Insulation – subcutaneous fat
Steroid
(A,D,E, and K)
carrier
shock absorber
• Are long-chain monocarboxylic acids
• Generally contain an even number of carbon atoms
FATTY ACIDS
FATTY ACIDS
• Short-Chain Fatty Acids
• Medium-Chain Fatty Acids
• Long-Chain Fatty Acids
– Less than 6 carbons
– 6-10 carbons
– More than 12 carbons
– Each C being “saturated” with H
Saturated Fatty Acids
Sat. Fatty Acids
– General Formula:
CH3 (CH2 )nCOOH
– Composed of at least one carbon-to carbon double bond
– Almost are in the cis configuration
Unsaturated Fatty Acids
– Composed of one carbon-to-carbon double bond
Monounsaturated Fatty Acids (MUFA)
– Composed of more than one carbon-to carbon double bond
Polyunsaturated Fatty Acids (PUFA)
– are identified by position of the double bond nearest the methyl end (CH3 ) of the carbon chain; this is described as an omega number;
Polyunsaturated Fatty Acids (PUFA)
– If PUFA has first double bond 3 carbons away from the methyl end =
omega 3 FA
- If PUFA has 6 carbons from methyl end =
omega 6 FA
– H’s on same side of the double bond; fold into a U-like formation; naturally occurring
cis-Fatty Acid
– H’s on the opposite side of the double bond; occur in partially hydrogenated food
trans-Fatty Acid
Fatty acids with double bonds before
the 9th carbon are
ESSENTIAL
Fatty acids with no double bonds before the 9th carbon are
NONESSENTIAL
Your body can form C=C double bonds after the 9th carbon
Nonessential
– Fatty acids react with alcohols to form esters and water
Esterification
are the products of the dehydration of a carboxylic acid and an alcohol.
Esters
- Producing fatty acids from esters
- Opposite of esterification
Acid Hydrolysis
– Is the base-catalyzed hydrolysis of an ester
Saponification
– the product of this reaction, an ionized salt, is a soap
Saponification
• Have a long uncharged hydrocarbon tail and a negatively charged terminus (the carboxylate terminus), they form micelles that dissolve oil and dirt particles
soap
Reaction at the Double Bond (Unsaturated Fatty Acids)
• Used in the food industry to convert polyunsaturated vegetable oils into saturated solid fats
Hydrogenation
• Carried out to add hydrogen to some, but not all, double bonds in polyunsaturated oils
• In this way liquid vegetable oils are converted into solid form (Crisco and margarine)
Partial Hydrogenation
• Are lipid esters that contain the glycerol molecule and fatty acids
GLYCERIDES
GLYCERIDES
2 classes
Neutral glycerides
Phosphoglycerides
Glycerides
– nonionic and nonpolar
– have polar region, the phosphoryl group, in addition to the nonpolar fatty acid tails
Neutral Glycerides
Phosphoglycerides
– Produce after the esterification of glycerol with a fatty acid
Neutral Glycerides
Esterification of glycerides may occur at one, two, or all three positions, producing:
• Monoglycerides
• Diglycerides
• Triglycerides
NONGLYCERIDE LIPIDS
Sphingolipids
Steroids
Cholesterol
– Are lipids that are not derived from glycerol
– Amphipathic and structural components of cellular membranes
Sphingolipids
Derived from sphingosine (long chain, Ncontaining alcohol)
2 TYPES
Sphingolipids
• Sphingomyelins
• Glycosphingolipids
– Located throughout the body, but are particularly important structural lipid components of nerve cell membranes
– Found in abundance in the myelin sheath the surrounds and insulate cells of the CNS
– Role is essential to proper cerebral function and nerve transmission
Sphingomyelins
– Include the cerebrosides, sulfatides, and gangliosides
Glycosphingolipids (Glycolipids)
Are built on a ceramide backbone structure, which is a fatty acid amide derivative of sphingosine
Glycosphingolipids
Cerebrosides – Are characterized by the presence of a single monosaccharide head group
– found almost exclusively in the membranes of brain cells
– Consists of ceramide joined to the monosaccharide galactose
Galactocerebroside
Cerebrosides – Are characterized by the presence of a single monosaccharide head group
– found in the membranes of macrophages
– Consists of ceramide bonded to the hexose glucose
Glucocerebrosides
– Contain the steroid nucleus (steroid carbon skeleton)
Steroids
• known sterol, found in the membranes
Cholesterol
– Amphipathic
– Involved in the regulation of the fluidity of the membrane as a result of the nonpolar fused ring
– Hydroxyl group is polar
– Perhydrocyclopentanophenanthrene ring
Cholesterol
________
• Can also exist in an esterified form called______, with the hydroxyl group conjugated by an ester bond to a fatty acid
– No polar groups making them very hydrophobic
CHOLESTEROL
cholesteryl ester,
• Almost exclusively synthesized by animals, but plants do contain other sterols similar in structure to cholesterol
• It is not readily catabolized by most cells, therefore, does not serve as a source of energy
CHOLESTEROL
T or F
Cholesterol can be a source of energy
False
Cholesterol
Can be converted in the liver to (2)
– Promote fat absorption in the intestine by acting as detergent
primary bile acids (e.g. cholic acid) and chenodeoxycholic acid
_______
– Are amphipathic derivatives of cholesterol
– Synthesized in the liver and stored in the gallbladder
(2)
Bile Salts
• Cholate
• Chenodeoxycholate
Emulsifying agent – whose polar hydroxyl groups interact with water and whose hydrophobic regions bind to lipids
Bile salts
Steroid Hormones
– Testosterone
– Progesterone
– Estrone, Estrogen, and its derivatives
– Cortisone and Cortisol
– Aldosterone
– Derived from many different sources and have a variety of chemical compositions, depending on the source
Long hydrocarbon tails – extremely hydrophobic – completely insoluble in water
Waxes
• – protective coating for hair and skin (used in skin creams and ointments)
Lanolin - wax
