1. Lipids Water insoluble Substances
Soluble in organic solvents (acetone, benzene)
Important in human nutrition
Very concentrated form of energy, important biomolecules
Types of Lipids
Simple Lipids: †Fatty Acids, †Triglycerides
Compound Lipids: †Phospholipids
†Cholesterol
†Eicosanoids
†Lipoproteins (VLDL, LDL, HDL, Chylomicrons)
†Fat Soluble Vitamins (A,D,E,K)

2. Fat Cells cellwww.umm.edu/.../graphics/images/en/19267.jpg

3. Mortality http://www.cartoonstock.com/lowres/mba0054l.jpg

4. Fatty Acids Structure

5. Fatty Acids
Fatty Acids - straight hydrocarbon chain with a terminal Carboxyl (COOH)
†Saturated- no double bond
†Unsaturated- contains > one double bonds
¶ Monounsaturated- one double bond
¶ Polyunsaturated- 2 or more double bonds
†Essential FA- body cannot produce, must come from diet
Formula .... CH3(CH2)nCOOH
†Carbon # varies (in nature normally even #)
i.e.: 16C, 18C
†Normally 4-24
† Most abundant

6. Always a 3 Carbons difference between double bonds
Linoleic and Linolenic are essential Fatty Acids

7. Fatty acids: different health effect
different kinds: food fats
Canola oil, olive oil, safflower oil, fish oil
butter, beef tallow, lard, palm oil, coconut oil
saturated
Unsaturated
monounsaturated,
polyunsaturated fatty acids
Omega 3 - , Omega 6 - fatty acids
essential fatty acids,
trans- fatty acids

8. Good Sources Monounsaturated fat: (plant: good source)
canola oil, olive oil
Polyunsaturated fat: (plant: good source)
vegetable oil, sunflower oil, safflower oil
Omega 3 fat - plant, fish
Tropical oil: palm oil, coconut oil: (Plant): highly saturated: limit the intake
Limit saturated fat: animal source butter, beef fat, lard

9. Omega 6-, Omega 3- Fatty Acids
Normally, numbering of Carbon starts at carboxyl carbon
In Omega system, numbering starts from the opposite end (CH3-, omega)
Linoleic acid : Omega 6 Fatty Acid
CH3-C-C-C-C-C=C-C-C=C-C-C-C-C-C-C-C-COOH
(First double bond is located on the 6th Carbon, this is an Omega 6 Fatty Acid)
Linolenic acid : Omega 3 Fatty Acid
CH3-C-C=C-C-C=C-C-C=C-C-C-C-C-C-C-C-COOH
(First double bond on the 3 Carbon)
Both are highly unsaturated

10. Omega-3 and Omega-6 Fatty Acids Compared

11. Omega 3 FA † Decreases incidence of cardiovascular disease
• Health Benefits
† Decreases incidence of cardiovascular disease
† Decreases blood cholesterol levels
† Decreases blood clotting by decreasing platelet aggregation
AMA Recommendation: Eat fish meal: 2-3 times /week (10 oz)
Good for brain development and function, normal vision, heart, immune system, memory
Fish oil supplements: recommended with consultation with a doctor

12. n-3 fatty Acids Come in the Diet
† Linolenic Acid- from plants
† Eicosapentaenoic Acid (EPA)- 20:5D
† Docosahexaenoic Acid (DHA)- 22:6D
Italicized---> highly unsaturated and originate in fish oils
Important for making 3 Types of Important Biomolecules
† Prostaglandins
† Leukotrienes
† Thromboxanes

13. Hydrogenation
Physical Property of fats
Saturated- animal foods (solid, room temp)
Mono, poly unsaturated fat - plant foods (liquid)
Adding “H” at the double bonds changes Liquid vegetable oil to solid: hydrogenation ( un-saturation  saturation):
Trans fatty acids (Trans fat)
Hydrogenation generates trans fatty acids,
Trans fats - fried foods

14. Hydrogenation 21

16. FDA - Trans Fat – Heart Disease
Food and Drug Administration in the United States as of (January 2006) requires food manufacturers to list trans fat on nutrition facts labels.
Read the ingredient label and look for shortening, hydrogenated or partially hydrogenated oil.
The higher up on the list, the more trans fat is present in the food.
A 1994 Harvard University study found more than twice the risk of heart attacks among those who ate partially hydrogenated oils, which are high in trans fat, compared to those who consumed little trans fat.
Trans fatty acids are responsible for nearly 30,000 premature deaths per year in the U.S.

17. “Potential” Dangers Consuming trans fats:
Increase the levels of bad cholesterol and promote heart disease and circulatory disorders.
Depress the body's immune system.
Interfere with pregnancy and are related to low birth weight babies, and poor quality breast milk.
Worsen diabetes, hypertension and obesity by increasing insulin resistance.
Displace healthy fats, for example, the omega-3 fatty acids in fish oils, preventing them from performing their normal function.
Disturb liver function.

18. Hydrogenation- addition of H+ at the double bond of liquid oil --> solid fat (increases the melting point) example: shortening or margarine
Emulsification- breakdown (dispersion) of large fat molecules into small fat particles (globules)
physiological emulsifiers- bile, lecithin examples: homogenization of milk
Rancidity and Oxidation (spoilage) of the double bond forms a peroxide: bad taste and smell
Antioxidant (Vit E) added to oil to prevent spoilage

19. Triglyceride (Triacylglycerol)
• Typically known as FAT
• Most abundant (in nature and in body) form of lipid
• Neutral Fat
Triacylglycerol
monoacyglycerol= monoglyceride
diacylglycerol = diglyceride
Triglyceride= glycerol + 3 Fatty Acids

20. Figure 6.5 Monoacylglycerol structure and stereospecific numbering.
Fig. 6-5b, p. 132

21. Figure 6.4 Chemical structure of a monoacylglycerol (left) and a diacylglycerol (right).
Fig. 6-4, p. 132

22. Triacylglycerol Structure

23. Structure of Triacylglycerol

24. Phospholipids (Glycerophosphatides)
• Structural Lipid
• Polar lipid
• 1 Glycerol + 2 Fatty Acid chains + 1 Phosphate Group
(+ another group to classify the P-lipid)
• Main lipid found in plasma membrane to give structure, and outside of lipoproteins

25. Phospholipids

26. Phospholipids

27. Phospholipids

28. Cholesterol in Plasma Membrane

29. Ch 10: Plasma Membrane: Lipid Bilayer
Phospholipids: have both hydrophobic and hydrophilic region
Forming bilayer: Allow: hydrophobic groups inside and hydrophilic groups outside of the membrane
Major: phosphatidyl choline (Lecithin)
Lecithin
In every single cell
Synthesized in the body
From foods: liver, egg yolk, soybean
Emulsifier

30. Phospholipids are Part of Lipoproteins
Transport vehicles for lipid in blood
Lipids are hidden inside lipoproteins
Chylomicron: made in intestine
VLDL: made in intestine, liver
LDL: made from VLDL in blood
HDL: made in intestine, liver

31. Cells Functional unit of life None typical: all different
Fig. 10.1: Human cell: Liver cell
Plasma membrane
Outer boundary
Keeps cell composition constant
Selective permeability

33. Animal Cell Membrane

34. Transport Mechanism

35. Na K ATPase

36. Na Glucose CoTransport

42. Cholesterol Structure

43. CH 32 Digestion and Transport of Dietary Lipids
Dietary Fat is made of
† Triglyceride (must abundant , 95% of total dietary fat)
† Phospholipids
† Cholesterol
† Fat Soluble Vitamins
Lingual Lipase in mouth and gastric lipase hydrolyze mostly milk fat (short and medium chain fatty acids (carbon # fewer than 12) (important during infancy)
Major digestion
Stomach contents enter Small Intestine--> release of cholecystokinin (CCK): gut hormone --> release of bile & pancreatic lipase , colipase, bicarbonate (neutralize acidic stomach contents) (hormone secretin stimulate bicarbonate release)
bile breaks fat into small particles
pancreatic lipase works on small fat particles
TG --> free fa + 2-monoglyceride + some glycerol

44. Triacylglycerols Digestion

45. Bile Bile recirculation Emulsifier: Break fat into small pieces
‘Bile’: made in Liver
stored in Gallbladder
acts in Small Intestine
reabsorbed in Ileum (Entero Hepatic Cycle) (intestine < --- >liver)
Bile recirculation
Total bile pool: 2.5 – 5.0 g
> 90% is reabsorbed, ~ 0.5 g is lost in feces/day
Pool of bile recycle twice/ meal
Soluble fibers bind to bile  excreted
Drugs bind to bile promote excretion of bile in feces  to lower blood cholesterol

46. Recycling of Bile Salts

48. Bile Salt

49. Action of Pancreatic Lipase

50. Cholesterol ester and phospholipids digestion

51. Fat Digestion

52. Fat Absorption Depending on the length of the fatty acids chain
† Short and medium chain fatty acids are absorbed --> portal vein --> liver
† Long chain FA, 2- monoacylglycerols, glycerol, bile, Vitamins, cholesterol and lysophospholipids aggregate to form micelle (lump of these particles)  micelles move to microville  all of these particles are absorbed into intestinal cells, bile is not absorbed.

53. Resynthesis of triacylglycerol in intestinal epithelial cells

54. Triacylglycerol (TG) Absorption
In the enterocyte, a “new” triaclyglycerol is formed from fat digested fragments absorbed from micelles---
“New” Triglyceride + Phospholipid + Fat Soluble Vitamins + Cholesterol: packaged, and apoprotein is added -
--> formation of lipoprotein
This lipoprotein is called Chylomicron (CM)
Chylomicron is too large to pass directly into the blood stream. Instead. It is taken through lymph.
CM is released into the bloodstream at thoracic Duct.

56. Made from exogenous (dietary) fat
Chylomicron
• Chylomicron-->high in TG, low in cholesterol, protein and phospholipids
Made from exogenous (dietary) fat
• Transported through lymph--> then, blood stream
• In blood, some TG in CM is digested by lipoprotein lipase in the capillary of adipose cells to Fatty acids and glycerol. Fatty Acids are take up by the adipose cells : what is left is called Chylomicron Remnants --> return to Liver

57. Lipoprotein Structure

58. Chylomicron

59. Chylomicron

60. 4 Types of Lipoproteins • Chylomicron made in intestine
• VLDL liver, intestine
• LDL circulation
• HDL liver, intestine
† if it has more fat than protein, then it’s a lower density lipoprotein like VLDL
† if more protein than fat, then it’s a higher density lipoprotein like HDL 

61. Fate of Chylomicron

62. Transfer of ApoE and ApoCII from HDL to chylomicron
Apo E is recognized by membrane receptor on liver cell: Apo E bearing particles enter liver by endocytosis  fused with lysosomes  digested  contents are reused
ApoCII: activator of LPL: enzyme on capillary endothelial cells on muscle and adipose cells: digest triacylglycerol of chylomicron and VLDL: fatty acids are taken in

64. Liver and Adipose in Lipid Metabolism
Exogenous free fatty acids of shorter chain: absorbed into portal vein  liver
Chylomicron remnant : enters the liver from blood circulation  in the liver cell, chylomicron remnant (c.r.) is fused with lysosome  all components of c. r. such as cholesterol, amino acids, phospholipids come out to cytosol. Absorbed dietary TG from c.r. and newly synthesized TG (from glucose metabolism) are packaged into VLDL
VLDL comes out to blood some TG is taken up by the body cell (mostly adipose cells)  what is left is IDL or LDL

65. Liver’s Importance in Lipid Metabolism
Site of bile formation: made from cholesterol
Synthesis of lipoprotein VLDL
VLDL is made from endogenously made fat (fat made in liver)
† VLDL is rich in TG and cholesterol
† VLDL leaves the liver--> blood --> some TG is taken up by cell  leaving it as IDL, then eventually made to LDL (rich in cholesterol % total content)
HDL is synthesized in peripheral tissue