1. Chapter 2 Lipids
2.1 - Lipids

2. LIPID Lipids include: 1. Fatty acids 2. Neutral fats and oils 3. Waxes
4. Phospholipid
5. Sterols
6. Fat soluble vitamins

3. Lipids
Lipids are
Biomolecules that contain fatty acids or a steroid nucleus.
Soluble in organic solvents but not in water.
Named for the Greek word lipos, which means “fat.”
Extracted from cells using organic solvents.

4. Types of Lipids The types of lipids containing fatty acids are Waxes.
Fats and oils (triacylglycerols).
Glycerophospholipids.
Prostaglandins.
Not steroids, as they do not contain fatty acids.

5. Structures of Lipids

6. Chapter 2 Lipids
2.2 - Fatty Acids

7. Lipids are non-polar (hydrophobic) compounds, soluble in organic solvents.
Most membrane lipids are amphipathic, having a non-polar end and a polar end.
Fatty acids consist of a hydrocarbon chain with a carboxylic acid at one end.
A 16-C fatty acid: CH3(CH2)14-COO-
Non-polar polar
A 16-C fatty acid with one cis double bond between C atoms 9-10 may be represented as 16:1 cis D9.

8. Fatty Acid Formulas The formulas for fatty acids are written as
Condensed formulas.
Line-bond formulas.
For example caprylic acid with 8 carbon atoms.
CH3—(CH2)6—COOH
CH3—CH2—CH2—CH2—CH2—CH2—CH2—COOH

9. Fatty Acids

10. Fatty Acids Fatty acids Are long-chain carboxylic acids.
Typically contain carbon atoms.
Are insoluble in water.
Can be saturated or unsaturated.

11. Saturated Fatty Acids
Octanoic Acid

12. Unsaturated Fatty Acids
3 - Octenoic Acid
3, 6 - Octadienoic Acid
Short hand: 8:1 (D3)
8:2 (D3,6)

13. Cis And Trans Fatty Acids
Cis 9 - Octadecenoic Acid (oleic)
Trans 9 - Octadecenoic Acid (elaidic acid)

14. Saturated Fatty Acids Saturated fatty acids have Single C–C bonds.
Molecules that fit closely together in a regular pattern.
Strong attractions between fatty acid chains.
High melting points that make them solids at room temperature. 14

15. Some Saturated Fatty Acids
TABLE 2.1
Copyright © by Pearson Education, Inc. Publishing as Benjamin Cummings 15

16. Unsaturated Fatty Acids
Have one or more double C=C bond
Typically contain cis double bonds.

17. Properties of Unsaturated Fatty Acids
Have “kinks” in the fatty acid chains.
Do not pack closely.
Have few attractions between chains.
Have low melting points.
Are liquids at room temperature.
“kinks” in chain

18. Polyunsaturated Fatty Acids
Linoleic acid: Cis, cis, 9, 12 - Octadecadienoic acid
Linolenic acid: Cis, cis, cis 9, 12, 15 - Octadecatrienoic acid
Arachidonic acid: Cis, cis, cis, cis 5, 8, 11, 14 – Eicosatetraenoic acid
  Linoleic Acid
Linolenic Acid
Arachidonic Acid

19. Some fatty acids and their common names:
Double bonds in fatty acids usually have the cis configuration.
Most naturally occurring fatty acids have an even number of carbon atoms.
Some fatty acids and their common names:
14:0 myristic acid; 16:0 palmitic acid; 18:0 stearic acid; :1 cisD9  oleic acid
18:2 cisD9,12  linoleic acid
18:3 cisD9,12,15  a-linonenic acid
20:4 cisD5,8,11,14  arachidonic acid

20. Comparing Melting Points of Some Fatty Acids
TABLE 2.1

21. Effects of Double Bonds on the Melting Points
16:0 60
16:1 1
18:0 63
18:1 16
18:2 -5
18:3
-11
20:0 75
Fatty. Acids.
Melting point. P. (0C)
20:4
-50

22. Melting Points and Solubility in Water of Fatty Acids

23. Omega-6 and Omega 3- Fatty Acids
In vegetable oils are mostly omega-6 with
the first C=C at C6.
linoleic acid
CH3─(CH2)4─CH=CH─CH2─CH=CH─(CH2)7─COOH 6
In fish oils are mostly omega-3 with the
first C=C at C3.
linolenic acid
CH3─CH2─(CH=CH─CH2)3─(CH2)6─COOH 3

24. Some Omega-6 and Omega-3 Fatty Acids

25. Prostaglandin: One of a number of hormone-like substances that participate in a wide range of body functions such as the contraction and relaxation of smooth muscle, the dilation and constriction of blood vessels, control of blood pressure, and modulation of inflammation. Prostaglandins are derived from a chemical called arachidonic acid

26. Prostaglandins Prostaglandins have
20 carbon atoms in their fatty acid chains.
An OH on carbon 11 and 15.
A trans double bond at carbon 13.
C 13
C 11
C 15 n

27. Prostaglandins in the Body
Prostaglandins are
Produced by injured tissues.
Involved in pain, fever, and inflammation.
Not produced when anti-inflammatory drugs such as aspirin inhibit their synthesis.

28. Chapter 2 Lipids
2.3 - Waxes, Fats, and Oils

29. Waxes
Waxes are
Esters of saturated fatty acids and long-chain alcohols.
Coatings that prevent loss of water by leaves of plants.
TABLE 2.2 29

30. Fats and Oils: Triacylglycerols
Fats and oils are
Also called triacylglycerols.
Esters of glycerol.
Produced by esterification.
Formed when the hydroxyl groups of glycerol react with the carboxyl groups of fatty acids.

31. FAT AND OILS Mostly Triglycerides: Glycerol 3 Fatty Acids
An ester forms when a hydroxyl reacts with a carboxylic acid, with loss of H2O.
Glycerol Fatty Acids

33. Triacylglycerols In a triacylglycerol,
Glycerol forms ester bonds with three fatty acids.

34. Triglyceride (b - palmityl distearin)
GLYCERIDES
Monoglyceride (a - monostearin) Diglyceride (a, a' - distearin)
Triglyceride (b - palmityl distearin)

35. Olive Oil
Olive oil
Contains a high percentage of oleic acid, which is a monounsaturated fatty acid with one cis double bond.

36. MELTING POINTS OF TRIGLYCERIDES
-15
C12 15
C14 33
C16 45
C18 55
C18:1 (cis)
-32
Triglyceride
Melting Point (°C)
C18:1 (trans)

37. Melting Points of Fats and Oils
A triacylglycerol that is a fat
Is solid at room temperature.
Is prevalent in meats, whole milk, butter, and cheese.
A triacylglycerol that is an oil
Is liquid at room temperature.
Is prevalent in plants such as olive and safflower.

38. Oils with Unsaturated Fatty Acids
Have more unsaturated fats.
Have cis double bonds that cause “kinks” in the fatty acid chains.
Cannot pack triacylglycerol molecules as close together as in fats.
Have lower melting points than saturated fats.
Are liquids at room temperature.

39. Diagram of Triacylglycerol with Unsaturated Fatty Acids
Unsaturated fatty acid chains have kinks that do not allow close packing.

40. Saturated and Unsaturated Fatty Acids In Fats and Oils

41. 2.4 - Chemical Properties of Triacylglycerols
Chapter 2 Lipids
2.4 - Chemical Properties of Triacylglycerols

42. Chemical Properties of Triacylglycerols
The chemical reactions of triacylglycerols are similar to those of alkenes and esters.
In hydrogenation, double bonds in unsaturated fatty acids react with H2 in the presence of a Ni or Pt catalyst.
In hydrolysis, ester bonds are split by water in the presence of an acid, a base, or an enzyme.

43. Hydrogenation of Oils The hydrogenation of oils
Adds hydrogen (H2) to the carbon atoms of double bonds.
Converts double bonds to single bonds.
Increases the melting point.
Produces solids such as margarine and shortening.

44. Hydrogenation Ni + 3H2 glyceryl tripalmitoleate glyceryl tripalmitate
(tripalmitolean)
glyceryl tripalmitate
(tripalmitin)

45. Hydrolysis In hydrolysis,
Triacylglycerols split into glycerol and three fatty acids.
An acid or enzyme catalyst is required. +3 + 3

46. Saponification and Soap
Is the reaction of a fat with a strong base.
Splits triacylglycerols into glycerol and the salts of fatty acids.
Is the process of forming “soaps” (salts of fatty acids).
With KOH gives softer soaps.

47. Saponification
Saponification - hydrolysis of ester under alkaline condition. + 3
+ 3NaOH
“soap”

48. Saponification Value of Fats and Oils
Saponification # it is mgs of KOH required to saponify 1 g of fat.
Fat
Saponification #
Milk Fat
Coconut Oil
Cotton Seed Oil
Soybean Oil
Lard

49. 3. Iodine Number
Iodine Number: it is grams of iodine absorbed by 100 g of oil.
Molecular weight and iodine number can calculate the number of double bonds. 1 g of fat adsorbed 1.5 g of iodine value = 150.

50. Iodine Value Determination
Iodine Value = (ml of Na2S2O3 volume for blank - ml of Na2S2O3 volume for sample)  N of Na2S2O3  0.127g/meq  100
Weight of Sample (g)
Excess unreacted ICl

51. Iodine Numbers of Triglycerides
Fatty Acids
# of Double-bonds
Iodine #
Palmitoleic Acid 1 95
Oleic Acid 1 86
Linoleic Acid 2
173
Linolenic Acid 3
261
Arachidonic Acid 4
320

52. 2.5 - Glycerophospholipids
Chapter 2 Lipids
2.5 - Glycerophospholipids
Fatty acid
Glycerol
Fatty acid
PO4
Amino
alcohol

53. Glycerophospholipids
Glycerophospholipids are
The most abundant lipids in cell membranes.
Composed of glycerol, two fatty acids, phosphate and an amino alcohol.
Glycerol
PO4
Amino
alcohol
Fatty acid

54. Glycerophospholipids Are Polar
A glycerophospholipid has
Two nonpolar fatty acid chains.
A phosphate group and a polar amino alcohol.
CH3 │
HO−CH2−CH2−N−CH HO−CH2−CH2−NH3 │
choline CH ethanolamine +
NH3
│ Amino alcohols
HO−CH2−CH−COO−
serine

55. Structure and Polarity of A Glycerophospholipid
Copyright © by Pearson Education, Inc. Publishing as Benjamin Cummings

56. Lecithin and Cephalin Lecithin and cephalin are glycerophospholipids
Abundant in brain and nerve tissues.
Found in egg yolk, wheat germ, and yeast.
Copyright © by Pearson Education, Inc Publishing as Benjamin Cummings

57. Chapter 2 Lipids
2.6 - Sphingolipids

58. Sphingolipids Sphingolipids Are similar to phospholipids.
Contain sphingosine (a long-chain amino alcohol), a fatty acid, phosphate, and a small amino alcohol.
Have polar and nonpolar regions.
sphingosine
PO4
amino
alcohol
fatty acid

59. Sphingosine
Sphingosine is a long-chain unsaturated amino alcohol. CH3−(CH2)12 −CH=CH−CH−OH │ CH−NH2 CH2−OH sphingosine

60. Sphingolipids In sphingomyelin, a sphingolipid found in nerve cells
There is an amide bond between a fatty acid and sphingosine, an 18-carbon alcohol.

61. Glycosphingolipids
Glycosphingolipids: contain monosaccharides bonded to the –OH of sphingosine by a glycosidic bond.

62. Glycosphingolipids and Cerebrosides
Are sphingolipids that contain monosaccharides.
Can be a cerebroside with galactose.

63. 2.7 - Steroids: Cholesterol, Bile Salts, and Steroid Hormones
Chapter 2 Lipids
2.7 - Steroids: Cholesterol, Bile Salts, and Steroid Hormones

64. Steroid Nucleus A steroid nucleus consists of 3 cyclohexane rings.
1 cyclopentane ring.
No fatty acids.
steroid nucleus

65. STEROLS Cholesterol Fat soluble vitamins Bile acids
Male & female sex hormones
Adrenal corticosteroids

66. Cholesterol Cholesterol Is the most abundant steroid in the body.
Has methyl CH3- groups, alkyl chain, and -OH attached to the steroid nucleus.
An important constituent of cell membranes, has a rigid ring system and a short branched hydrocarbon tail.
Cholesterol is largely hydrophobic, but it has one polar group, a hydroxyl, making it amphipathic.

67. Cholesterol inserts into bilayer membranes with its hydroxyl group oriented toward the aqueous phase & its hydrophobic ring system adjacent to fatty acid chains of phospholipids.
The OH group of cholesterol forms hydrogen bonds with polar phospholipid head groups.

68. Cholesterol in the Body
Is obtained from meats, milk, and eggs.
Is synthesized in the liver.
Is needed for cell membranes, brain and nerve tissue, steroid hormones, and Vitamin D.
Clogs arteries when high levels form plaque.
Considered elevated if plasma cholesterol exceeds 200 mg/dL.
A normal, open artery.
An artery clogged by cholesterol plaque

69. TABLE 2.4

70. FAT SOLUBLE VITAMINS
Vitamin A:

71. Vitamin D2:
Vitamin E:

72. Bile Salts Bile salts Are synthesized in the liver from cholesterol.
Are stored in the gallbladder.
Are secreted into the small intestine.
Have a polar and a nonpolar region
Mix with fats to break them part.
Emulsify fat particles to provide large surface area.

73. Bile Salts
Polar region
Nonpolar region

74. Steroid Hormones (Sex Hormones)
Are chemical messengers in cells.
Are produced from cholesterol.
Include sex hormones such as androgens (testosterone) in males and estrogens (estradiol) in females.

76. Adrenal Corticosteroids
Adrenal corticosteroids are steroid hormones that
Are produced by the adrenal glands located on the top of each kidney.
Include aldosterone, which regulates electrolytes and water balance by the kidneys.
Include cortisone, a glucocorticoid, which increases blood glucose level and stimulates the synthesis of glycogen in the liver.

77. Adrenal Corticosteroids

78. Lipoproteins Lipoproteins
Combine lipids with proteins and phospholipids.
Are soluble in water because the surface consists of polar lipids.

79. Types of Lipoproteins Lipoproteins
Differ in density, composition, and function.
Include low-density lipoprotein (LDLs) and high-density lipoprotein (HDLs).
TABLE 2.5 79