- 1. Lipids Compiled by group 5 Imanuelle Orchidea Meiliza
Ekayanti Teguh Permana
2. overview Lipids are diverse in form and are defined by
solubility in non-polar solvents (and insolubility in water) Lipids
are used for efficient energy storage, as structural components of
cell membranes, as chemical messengers and as fat-soluble vitamins
with a variety of functions Our cells can also biosynthesize most
lipids 3. Types of Lipids Following is a summary of the types of
lipids we will study and their general structures: 4. Fatty Acids
The simplest lipids are the fatty acids, which rarely exist alone
in nature, but instead are usually a component of more complex
lipids Fatty acids are carboxylic acids with a long hydrocarbon
chain attached Although the acid end is polar, the nonpolar
hydrocarbon tail makes fatty acids insoluble (or sparingly soluble)
in water Fatty acids can be classified by how many double bonds are
present in the hydrocarbon tail: - Saturated fatty acids have only
single bonds - Monounsaturated fatty acids have one double bond -
Polyunsaturated fatty acids have two or more double bonds 5. Lipids
may be broadly defined as hydrophobic or amphipathic small
molecules that originate entirely or in part by carbanion-based
condensations of thioesters and/or by carbocation-based
condensations of isoprene units 6. Building Blocks 7. Structures
and Melting Points of Saturated Fatty Acids 8. Physical Properties
of Saturated Fatty Acids Saturated fatty acids have: Molecules that
fit closely together in a regular pattern Strong attractions
(dispersion forces) between fatty acid chains High melting points
that makes them solids at room temperature. 9. Structures and
Melting Points of Unsaturated Fatty Acids 10. Physical Properties
of Unsaturated Fatty Acids Unsaturated fatty acids have: Nonlinear
chains that do not allow molecules to pack closely Weak attractions
(dispersion forces) between fatty acid chains Low melting points
and so are liquids at room temperature 11. Triglycerides The
triesters of fatty acids with glycerol (1,2,3trihydroxypropane)
compose the class of lipids known as fats and oils. These
triglycerides (or triacylglycerols) are found in both plants and
animals, and compose one of the major food groups of our diet.
Triglycerides that are solid or semisolid at room temperature are
classified as fats, and occur predominantly in animals. Those
triglycerides that are liquid are called oils and originate chiefly
in plants, although triglycerides from fish are also largely oils.
12. Fats and Oils Formed from glycerol and fatty acids O
CH2OHCHOHHO+C O(C H 2 ) 1 4 C H 3HOC(C H 2 ) 1 4 C H 3O CH2OHg lyc
e ro lHOC(C H 2 ) 1 4 C H 3p a lm itic a c id (a fa tty a c id )17
13. Triglycerides (triacylglcerols) Esters of glycerol and fatty
acids e ste r b o n d s O CH2OC(C H 2 ) 1 4 C H 3+H 2O(C H 2 ) 1 4
C H 3+H 2O+H 2OO CHOC OCH2OC(C H 2 ) 1 4 C H 318 14. Non-fatty Acid
Lipids Non-fatty acid lipids are steroids group Contains steroid
chain structure The most familiar lipid with steroid chain is
cholesterol Cholesterols are biosynthesized naturally in our bodies
15. Cholesterol BiosynthesisConversion of
3-hydroxy-3-methyl-glutaryl-Coenzyme A to mevalonate by HMG CoA
reductase. This is the rate limiting step in cholesterol
biosynthesis. 16. Trivial Names of Fatty Acids Trivial names (or
common names) are non-systematic historical names, which are the
most frequent naming system used in literature. Most common fatty
acids have trivial names in addition to their systematic names (see
below). These names frequently do not follow any pattern, but they
are concise and often unambiguous. 17. Saturated FormulaCommon
NameMelting PointCH3(CH2)10CO2Hlauric acid45
CCH3(CH2)12CO2Hmyristic acid55 CCH3(CH2)14CO2Hpalmitic acid63
CCH3(CH2)16CO2Hstearic acid69 CCH3(CH2)18CO2Harachidic acid76 C 18.
Unsaturated FormulaCommon NameMelting
PointCH3(CH2)5CH=CH(CH2)7CO2Hpalmitoleic acid0
CCH3(CH2)7CH=CH(CH2)7CO2Holeic acid13
CCH3(CH2)4CH=CHCH2CH=CH(CH2)7CO2Hlinoleic acid-5
CCH3CH2CH=CHCH2CH=CHCH2CH=CH(CH2)7CO2Hlinolenic acid-11
CCH3(CH2)4(CH=CHCH2)4(CH2)2CO2Harachidonic acid-49 C 19. Systematic
names Systematic names (or IUPAC names) derive from the standard
IUPAC Rules for the Nomenclature of Organic Chemistry, published in
1979,[6] along with a recommendation published specifically for
lipids in 1977.[7] Counting begins from the carboxylic acid end.
Double bonds are labelled with cis-/trans- notation or E-/Z-
notation, where appropriate. This notation is generally more
verbose than common nomenclature, but has the advantage of being
more technically clear and descriptive. Example : (9Z)-octadecenoic
acid (oleic acid) 20. Delta-x nomenclature In x (or delta-x)
nomenclature, each double bond is indicated by x, where the double
bond is located on the xth carboncarbon bond, counting from the
carboxylic acid end. Each double bond is preceded by a cis- or
trans- prefix, indicating the conformation of the molecule around
the bond. For example, linoleic acid is designated "cis-9, cis-12
octadecadienoic acid". This nomenclature has the advantage of being
less verbose than systematic nomenclature, but is no more
technically clear or descriptive. 21. n-x Nomenclature nx (n minus
x; also x or omega-x) nomenclature both provides names for
individual compounds and classifies them by their likely
biosynthetic properties in animals. A double bond is located on the
xth carboncarbon bond, counting from the terminal methyl carbon
(designated as n or ) toward the carbonyl carbon. For example,
-Linolenic acid is classified as a n3 or omega-3 fatty acid, and so
it is likely to share a biosynthetic pathway with other compounds
of this type. The x, omega-x, or "omega" notation is common in
popular nutritional literature, but IUPAC has deprecated it in
favor of nx notation in technical documents 22. Hydrogenation O
CH2OC(C H 2 ) 5 C H C H (C H 2 ) 7 C H 3O CHOCNi (C H 2 ) 5 C H C H
(C H 2 ) 7 C H 3+ 3H2O CH2OC(C H 2 ) 5 C H C H (C H 2 ) 7 C H 329
23. Product of Hydrogenation 30O CH2OC(C H 2 ) 1 4 C H 3O CHOC(C H
2 ) 1 4 C H 3O CH2OC(C H 2 ) 1 4 C H 3Hydrogenation converts double
bonds in oils to single bonds. The solid products are used to make
margarine and other hydrogenated items. 24. Hydrolysis
31Triglycerides split into glycerol and three fatty acids (H+ or
enzyme catalyst) O CH2OC(C H 2 ) 1 4 C H 3O CHOCH (C H 2 ) 1 4 C H
3++3 H 2OO CH2OC(C H 2 ) 1 4 C H 3 CH2OHCHOHCH2OHO +3 HOC(C H 2 ) 1
4 C H 3 25. Saponification and Soap 32 Hydrolysis with a strong
base Triglycerides split into glycerol and the salts of fatty acids
The salts of fatty acids are soaps KOH gives softer soaps 26. O
CH2OC(C H 2 ) 1 6 C H 3O CHOC(C H 2 ) 1 6 C H 3+ 3 N aO HO CH2OC(C
H 2 ) 1 6 C H 3 C H2OHCHOH + 3 N aC H2OHO + -OC(CH 2 ) 14 C H 3s a
lts o f fa tty a c id s (s o a p s ) 33 27. Explanation The
presence of a soap or a detergent in water facilitates the wetting
of all parts of the object to be cleaned, and removes
water-insoluble dirt by incorporation in micelles The surfactant
molecules reversibly assemble into polymolecular aggregates called
micelles. By gathering the hydrophobic chains together in the
center of the micelle, disruption of the hydrogen bonded structure
of liquid water is minimized, and the polar head groups extend into
the surrounding water where they participate in hydrogen bonding.
These micelles are often spherical in shape, but may also assume
cylindrical and branched forms, as illustrated on the right. Here
the polar head group is designated by a blue circle, and the
nonpolar tail is a zig-
