LIPIDS AND FATSLIPIDS AND FATS
• *A group of organic substances that are greasy to touch and insoluble to H2O but
• soluble in organics solvents/non-polar solvents such as ether, benzene, alcohol and choloroform.
• Contain C,H,O but compared to carbohydrates, have less O2 in proportion to C & H
• Basic structural unit: fatty acids• Are chemically composed of 5 main
elements: C, H,O, N, P.• Composed of about 5% of the organic
matter of the cell.
FATSFATS
• Simple lipids
• Most concentrated source of energy
• Composed of C, H and O but C is greater in number and ratio of H to O is higher
• Solid at room temperature
OILOIL
• Physical state of fats that is liquid at room temperature
• Example: Mineral and lubricating oil from petroleum or oil of cloves
TrigycerideTrigyceride
• Chemical and clinical names for fats and oils
• Ester of glycerol and fatty acids
• Form of fats found in foodstuff and fat depot of most animals
GlycerolGlycerol
• 3 carbon chain which makes up the core of fat molecules, such that 1 molecule of fatty acid is attached to each of the 3 carbon unit of glycerol
H - glycerine linkage
H C OH HOOC R(CH)
H C OH HOOC R(CH)
H C OH HOOC R(CH)
H
Glycerol Fatty Acid Simple Triglyceride Tristearin
• If R1R17 and R33 are different they are considered mixed triglyceride
• Example– R1 C17 H33 Oleic Acid
– R2 C17 H35 Stearic Acid
– R3 C15 H31 Palmitic Acid
Functions of LipidsFunctions of Lipids1. Source of Energy
Fat as the most concentrated source of energy 9 cal/g
As adipose tissue, it is the major source of energy stored in quantity by the body
Fat is converted to acetyl CoA which yields great mount of ATP
2. Source of Essential Fatty Acids– From seed oils of wheat germ, corn
soybean, walnut, cotton seeds3. Carrier of Fat soluble vitamins and their
precursor
4. Insulation• subcutaneous layer of fat reduces heat
loss in cold weather (helps maintain body temperature)
• Excessive heat layer or subcutaneous fats (obesity) interfere with heat loss during warm weather thereby increasing discomfort
5. Protection of Vital Body Organs• -especially from physical shock
6. Palatability– Responsible for flavors and aroma of
foods in the diet– It stimulates flow of digestive juices
7. Satiety value– Fats retard the emptying of the stomach
(reduce gastric motility) and stay longer therefore delays the onset of hunger which makes the individual feel satisfied for a longer period of time
8. Acts at emulsifying agentLecithin helps in transport of fatty substances that cannot easily pass through the cell membrane
9. Lubricants Which aid in elimination10. Precursor of Prostaglandins Participates in the regulation of blood
pressure, heart rate and lipolysis11. Body Composition Female 18-25% of BW
Male 15-20%
12. Important constituent of tissue/cell membrane structure (phospholipids, cholesterol) - 30-40% lipids; 60-7-% proteins; RBC – phosphoglycerides
13. protective form of cell walls of many bacteria; leaves of higher plants; or the exoskeleton of insects and the skin of the vertebrates;
in animals, the waxes keep feathers, skin and hair soft, pliable and H2O repellant. While the cuticle waxes of plants protect them both from dehydration and from invasion of harmful organisms
14. As enzyme cofactors ( some fat soluble vitamins).
15. As transport form of some neurotransmitters ex. Acetylcholine
16. As receptors in nerve ending membranes.
17. As determinants of immunological specificity
Fatty AcidsFatty Acids
• Consist of a chain series of Carbon attached to a carboxyl group which concerns the acidic property of the compound
• They give a diversity and chemical specificity to the natural fats, similar to that given to proteins by amino acids
Classification of LipidsClassification of LipidsI. Classification by White – based on the
presence or absence of glycerol.
1. Fatty Acids
2. Lipids containing glycerol
a. Neutral fats (triacylglycerols)
b. Phosphoglycerides
c. Cardiolipin
d. Plasmologens
3. Lipids not containing glycerol a. Sphingolipids b. Aliphatic alcohol and waxes c. Terpenes 2 major grps of d. Steroids non-saponifiable lipids e. Prostaglandins 4. Lipids combined with other classes of
compounds a. Lipoproteins and proteolipids b. Glycolipids
II. Classification by Bloors:A. Simple Lipids- ester of fatty acids or other
alcohol
1. neutral fats or trigyceride 3 fatty acids combined with glyceride 2 fatty acids + glycerol + diglyceride 1 fatty acid + glycerol + monoglyceride– simple fats- all fatty acids are the same – Mixed fats- at least 2 fatty acids are
different
2. Waxes-at least 2 fatty acids with an alcohol other than glycerol
- long chain or cyclic alcohol - they are not digested by fat
splitting enzyme, so no nutritional value
- includes esters of cholesterol, Vitamin A and D
B. Compound Lipids- esters of fatty acid containing
groups in addition to an alcohol and fatty acid (CHO phosphate or nitrogenous group)
1. Phospholipids- fats containing H3PO4 and a
nitrogenous base in addition to fatty acid and glycerol
- plays an important role in the transport of fat to the different tissues and appear to be involved in its utilization
– Lecithin- emulsifying agent
– Cephalin- thromboplastic substance which initiates blood coagulation
2. Glycolipids- contains carbohydrate and nitrogenous
base
example: Cerebrosides which contain a molecule of glucose or galactose
3. Aminolipids or lipoproteins
- lipid molecule bound to protein; facilitate transport in the aqueous medium of blood
C. Derived Lipids- derivatives of simple and compound lipids due to
hydrolysis. - Some contain N or P or both, other contain S1. Fatty Acids2. Glycerol3. Steroids
1. Sterols- cholesterol2. Bile Acids- glycocholic acid3. Sex Hormones- progesterone4. Adrenal corticosterol5. Vitamin D
1. ergocalciferol (D1)
2. Cholicalceferol (D3)
FATTY ACIDSFATTY ACIDS• Content of fats and oils which are the
basis of their physical and chemical properties
• The most abundant occurring lipids• The building blocks of several classes
of lipids and neutral fats, phosphoglycerides, glycolipids, cholesterol esters and some waxes
• Products of fat hydrolysis
A. Structure of Fatty acidsA. Structure of Fatty acids
1.They are mainly straight chain aliphatic, monocarboxylic acids, ranging in chain lengths from 4 to 24 C atoms.
2.Type formula
( hydrophobic – R – COOH – hydrophilic)
3. FA maybe saturated and unsaturated
4. Most naturally occurring fatty acids are even numbered containing 16 to 18 C atoms.
5. Double bonds in naturally occurring fatty acids are always in a cis – as opposed to trans – configuration
a. the presence of the double bond gives rise to the possibility of geometric isomerism
b. the double bond forms around which the rest of the molecules maybe oriented; if the radicals are on the same side of the bond, the compound is called a cis – form; if on opposite sides, a trans – form.
HOOH(CH2)7CH CH(CH2)7COOH CH3(CH2)7CH CH3(CH2)7CHcis-oleic acid trans-elaidic acidCH3 H CH3 H
C C C C H H COO
COO
Classification of Fatty AcidsClassification of Fatty Acids1. Essential or indispensable Fatty Acids
When the body cannot synthesize them from other substance, it must be provided in the diet
Examples:• Linoleic Acid- (n-6 PUFA) sole dietary• Linolenic Acid- (n-3 PUFA) promotes growth• Arachidonic Acid- promotes growth
Deficiency in the diet produces:
1. Impairment of growth
2. Some form of dermatitis
3. Excessive thirst
4. Kidney damage in advance cases
5. Some cases of eczema and dermatosis- caused by vit. A deficiency are cured by addition of indispensable FA
2. Unsaturated Fatty Acids- if f.a. contains 1 double bond
monounsaturated, (oleic)- if f. a. contains 2 or more double bonds
polyunsaturated, (linoleic a., linolenic a., arachidonic a.)
• Unstable and reactive due to the presence of (=) bonds.
• Ends in “enoic”
Most important unsaturated fatty Most important unsaturated fatty acids:acids:
1. Oleic acid (C18H34COOH) – olive oil
CH3 (CH2)7 CH = CH (CH2)7 COOH
2. Linoleic acid (C18H32COOH) – corn oil
CH3 (CH2 )4 CH = CHCH2CH
= CH (CH2)7 COOH
3. Linolenic acid (C18H30COOH) – linseed oil
CH3CH2CH = CHCH2CH = CHCH2CH
= CHCH (CH2)7 COOH
Importance of Unsaturated FAcidsImportance of Unsaturated FAcids
1. Maintains normal growth and reproduction of lower animals
2. Prevents eczematous lesions of skin in man
3. Lowers the serum cholesterol level in man (polyunsaturated type)
3. Saturated Fatty Acids3. Saturated Fatty Acids• Fatty acids wherein the C atom holds as many H as it can hold.• Found in animal and vegetable fats (coconut and peanut oil)
H H
C C with w hydrogen atoms attached to each C atom
H H
eg,. Stearic Acid, Palmitic acid, myristic acid
• Contains up to 8C atoms; belong to acetic acid series w/ general formula of CnH2nO2
• Saturated fatty acids has no double bonds• Systematic name ends in “anoic”
ex. Lauric or duodecanoic – C12
myristic or tetradecanoic – C14
palmitic or hexadecanoic – C16
stearic or octadecanoic – C18
Classificattion of SFA accdg to the no. of C atoms:
1. Short chain – w/ < 6 C atoms
ex. Butanoic – 4 C atoms; pentanoic – 5 C
2. Medium chain – w/ 6-10 C atoms
ex. Heptanoic, octanoic, nonanoic, decanoic
3. Long chain – w/ H and more C atoms
ex. Dodecanoic, octadecanoic
Nomenclature of Fatty acidsNomenclature of Fatty acids1. Delta ( ) system – C atoms are numbered beginning
from the carboxylic end (COOH) ex. Linoleic acid - 18: 2c 9, 12 COOH CH3 2. N system (Number system) counting starts from the
methyl end of the molecule ex. Linoleic acid – 18: 2n – 6, 93. Omega system
Some metabolically important FA:Some metabolically important FA:Common name Systematic
nameNo. of C atoms
No. of = bonds
Chemical formula Occurrence
Lauric duodecanoic 12 0 C12H24O2 Laurel,
coconut
oil
Myristic tetradecanoic 14 0 C14H28O2 Coconut,nutmeg
Palmitic hexadecanoic 16 0 C16H32O2 Plants & animal fats
Stearic octadecanoic 18 0 C18H36O2 Animal fats
Palmitoleic Cis 9 hexadecanoic
16 1 C16H30O2 Butter, fish, oils,
hen fat
Oleic Cis 9 octadecanoic
18 1 C18H34O2 Cottonseed oil
Linoleic Cis 9 octadecadienoic
18 2 C18H32O2 Linseed oil
Linolenic All-cis-9,12,15 octadecatrienoic
18 3 C18H30O2 Linseed oil
Arachidonic All cis - 5,8,11,14 eicosatetraenoic
20 4 C20H32O2 Lecithin, cephalin, liver,
fish
Physical properties of Fatty acids:Physical properties of Fatty acids:1. Odorless, tasteless,colorless, greasy to
touch2. Insoluble to water but are soluble in
organic solvents such as chloroform, methanol, ether or benzene, carbon tetrachloride
3. Only small amounts are present in nature; abundant in amide or ester linkage
4. Boiling point and melting point rise w/ inc in chain length;inc. C atoms – inc. melting point – less soluble
5. At physiological ph, fatty acids are ionized and possess amphipathic character ( their hydrocarbon tail is hydrophobic while the carboxylic head (COOH) is hydrophilic.
6. Solubility decreases (inversely proportional) w/ increasing chain length. FA w/ R groups higher than C6 are only slightly soluble in water.
7. Specific gravity of fats is less than 0.
Chemical properties of FA due to Chemical properties of FA due to double bonds:double bonds:
1. Hydogenation- addition of hydrogen; hardening – UFA – hydrogenated by gaseous hydrogen in the presence of catalyst like platinum, palladium or nickel
* principle involved in the manufacture of artificial butter (oleomargarine) from vegetable oils.
2. Halogenation – Br and I
3. Oxidation leading to rancidity
exposure to air – acidic UFA – due to hydrolysis – liberation of volatile FA – formation of peroxides,odoriferous volatile aldehyde, ketones and acids – rancid odor
Lipoxidase – enzyme causing rancidity of fats and oils at room temperature
- change maybe catalyzed by bacteria
Types of rancidity
1. Hydrolytic rancidity – bad odor and taste are due to the free FA liberated (hydrolysis)
ex. Butterfat – w/ high %age of volatile FA
2. Oxidative rancidity – caused by oxidation of UFA and their = bonds w/ the production of shortered chain acids, aldehydes and ketones;more impt. type
ex. Tallowy butter – dairy industry
* O2 is necessary for oxidative rancidity. Light, heat, moisture and traces of certain metals such as Cu hasten the oxidative process
Due to COOH (carboxylic acid)Due to COOH (carboxylic acid)1. Esterification – a very slow reaction but maybe
accelerated by heat or addition of hydrogen ion2. Saponification – metallic salts of fatty acids
(soaps) will be produced when treated w/ alkali. - Na & K salts are soluble in water Na salts – hard soaps K salts – soft soaps - Ca & Mg salts and the heavy metals such as
Pb & Zn are insoluble in water3. Hydrolysis – fats are hydrolyzed by dilute acids
to FA and glycerol
• Assignment: ( Watch LORENZO’S OIL FILM )• 1. What ails the main character in the story? What are
the symptoms presented?• 2. What are the preventive measures/cure given to
remedy the problem?• 3. Is there a real cure to Lorenzo’s disease/illness?• 4. What is the mixture of Lorenzo’s oil?• 5. How will you relate the subject Biochemistry in the
story? • Write your answers in a one whole intermediate pad
paper. Submission is on Friday.• We’ll have discussion of Lipids and about the film.
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