AN SC 260 Ch.5

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AN SC 260 Ch.5
2012-10-14 14:57:34
AN SC 260

Lipids in animal nutrition
Show Answers:

  1. What are lipids?
    • • Organic compounds
    • – Relatively insoluble in water
    • – Relatively soluble in organic solvents
    • – High content of hydrocarbons
  2. What are fatty acids?
    • • Carbon chains
    • – 2 – 24+ C atoms long
    • – Most animal and plant fats: are Straight (ie. not branched) chains are even number of carbons
    • - tend to have a methyl non polar hydrophobic end and a caboxyl end which is polar and hydrophillic
  3. Acetic acid formula?
    • Acetic acid – C2H4O2
  4. What does chain lenghth tell you about the lipid?
    • Longer chains tend to be more solid
  5. what does a short-chain (< 6 C) fatty acids tell you?
    • • Product of microbial fermentation of fibre
    • • Volatile (gas)
  6.  what does medium-chain (6 to 12 C) fatty acids tell you? 
    • • MC triglycerides easy to absorb (water-soluble)
    • • Product of digestion – palm kernel oil high in MC TG
  7. what does Long-chain (>12 C) fatty acids tell you?
    • most feed fats/oils
  8. What does very long-chain (>22 C) fatty acids tell you?
    • Specialized feed fats/oils – eg fish oil
  9. What is a saturated fatty acid?
    • – No double bonds
    • – Straight chain
    • – Tend to be solid at room temperature (fats)
  10. What is an unsaturated double bond? 
    • – At least one double bond
    • – Each cis double bond introduces a “kink” into the molecule
    • – Tend to be liquid at room temperature (oils)
  11. Monounsaturated vs polyunsaturated. How far do the bonds appear away from each other? 
    • Double bonds normally appear 3 C apart
  12. Trans vs Cis unsaturated fatty acids
    Trans fatty acids both the hydrogens are opposite sides of double bond compared to cis where they are on the same side of the hydrocarbon chain
  13. What is hydrogenation in trans fatty acids? How do they behave after hydrogenation? Who does this process naturally?
    • - Catalytic
    • - Biohydrogenation
    • - removal of the doube bond by addition of hydrogen

    - They behave like saturated fats because the double bond has been removed. Has negative effects to human health

    - Hydrogenation is preformed by rumen microbes as they dont like unsaturated fats so they change them to saturated 
  14. What is CLA? 
    Is a trans fatty acid (conjugated linolic acid) - but it reduces fat deposition and lowers inflammation. 
  15. Nomenclature: 18 carbons 2 double bonds at carbon 9 and 12. Common name? 
    Systemic name? Standard notation? Omega notation?
    • -linoleic acid
    • -9, 12 octadecadienoic acid
    • -18:2(9,12)
    • -18:2(n-6)
  16. How does standard notation work? Omega notation? 
    • • Carbons numbered beginning at the acid (carboxyl or COOH) end
    • – Also position of double bonds
    • - Carbons numbered beginning at the methyl end
  17. What is better omega or standard notation? 
    • • Fatty acid chains are lengthened by adding 2 C units at the carboxyl end
    • – Also shortened at carboxyl end (β-oxidation)
    • • Position of omega bonds remain constant – Metabolic differences
  18. What doe it mean Essential fatty acids? Examples?
    – Cannot be synthesized de novo by animals

    • • Linoleic acid (C18:26)
    • • Linolenic acid (C18:3 3)
    • • Arachidonic acid (C20:46)
    • – Conditionally essential
    • – Can be synthesized by most animals if linoleic acid present
  19. When you have branched and odd numbered fatty acid chains what does this tell you? example?
    • – Most are products of microorganisms
    • • Presence in ruminant tissues

    ex. lactobacillic acid
  20. Simple lipids? Examples
    • – Esters of fatty acids with various alcohols
    • – Fats and oils – glycerol + fatty acids
    • – Waxes – other alcohols + fatty acids
  21. Compound lipids? Examples?
    • – Esters of fatty acids containing non-lipid substances
    • • CHO, phosphorus, or proteins
  22. What are glycerides? 
    • – Plant, animal storage of energy
    • – Major form of lipid in the body
  23. What are Simple triglycerides? What is their lenghth? Saturation? 
    – Same fatty acid structure at all 3 positions

    • – Chain length (also depends on saturation)
    • • <10 C chain – liquid at room temperature
    • • >10 C chain – solid at room temperature

    • – Chain saturation (also depends on length)
    • • State (liquid or solid) depends on degree of saturation
  24. Mixed triglycerides? What is their state at room temperature?  
    - Considered a mixed tri if fatty acid structures not all the same

    -  Depends on mixture of fatty acids – Chain length and degree of saturation
  25. Why is there a difference in the melting point between stearic acid and linoleic acid?
    • Stearic acid (70 degrees) the chains interact with each other thus it is able to have a high melting point.
    • Compared to linoleic acid (-5 degrees) where there is double bonds and thus aren't able to interact as closely and have a low melting point
  26.  What are Sterols? Function? Examples
    - Multiple ring structure

    • – Bile acids
    • – Sex hormones
    • – Adrenal hormones
    • – Vitamin D
    • – Cholesterol

    • Cholesterol, ergosterol and cholecalciferol
  27. What are Phospholipids? Functions? 
    • Derivatives of triglycerides
    • – 2 fatty acid molecules
    • – 1 phosphate group

    • • Phospholipid bilayer
    • • Cell membranes
    • – Allow fat and water to cross membrane

    • • Emulsifying properties
    • – Lipid transport
    • • Keep lipids suspended in blood
    • – Fluidity of cell membranes
  28. Glycolipids?
    • • Phospholipids to which a carbohydrate chain is attached
    • – Often have markers for cellular recognition
  29. Lipoproteins? Examples? 
    • • A biochemical assembly that contains both proteins and lipids
    • – Covalently or non- covalently bound

    • Many enzymes, transporters, antigens, toxins
  30. Digestion/ absorption in the mouth?
    • – Physical emulsification
    • – Secretion of lingual lipase (secreted from the tongue, starts to break down fats)
  31. Digestion/ absorption in the stomach?
    • – Physical emulsification
    • – Activity of lingual lipase
  32. Digestion/ absorption in the small intestine? 6 things?
    • – Most digestion, all absorption
    • – Secretion of lipase from pancreas
    • – Form large droplets in chyme the movement to microvilli impaired
    • – Fats are not soluble in water they have a small surface area:volume
  33. Bile salts description? 
    • – Cholesterol-based
    • – Detergent
    • • Sterol region and Carboxyl region
  34. What do bile salts do? 
    • – Emulsify fats, are secreted by the liver 
    • – Have a Detergent activity
    • •  create Smaller droplets
    • •  increase  surface area
    • •  allow more lipase activity

    - They are also negatively charged so when they attach on the surfaces of fats they begin to repel each other. 
  35. What does intestinal pancreatic lipase do? 
    • – Work at oil-water interface
    • – Cleave TG in 1 and 3 position
    • • leaveing 2 fatty acids and 1 monoglyceride and Glycerol
  36. How is cholesterol created? 
    – Cholesteryl esters cleaved to cholesterol and free fatty acid
  37. What are fat globules made of? 
    • – Triglycerides
    • – Cholesterol
    • – Fat-soluble vitamins
  38. When lipid globules are futher reduced in size what is created? What are they made of? Where do they go?
    Micelles are formed. They are made of bile salts, monogylerides, fatty acids, phospolipids, and cholesterol. There small size allows them to migrate towards the villi. 
  39. How are the micelles absorped? 
    • Absorbed through intestinal cell membrane thru diffusion
  40. How are micelles formed? Where do they go?
    In the precesnce of bile salts, monoglyerides form micelles that are water watery intestine environment. Eventually the monoglycerides leave the micelle to enter the cell. Once the monoglyerides are in the cell they again come back together to form triglyerides. 
  41. What happens once the monoglycerides are in the enterocyte? 
    • – Longer chain (>C12) fatty acids re-formed into TG
    • – Shorter chain (<C12) fatty acids absorbed into lymph in most animals
    • – Cholesterol re-esterified
  42. lipids are incorporated in chylomicrons? What are chylomicrons? 
    • They are coated with lipoporteins.
    • They contain TG, Phospholipids, Cholesterol esters, Free Cholesterol, and Protein
  43. How do chylomicrons leave the enterocyte in mammals and birds? 
    By reverse pinocytosis for both. In mamals they leave by the lymph and in birds they leave by portal blood. 
  44. Where is cholesterol synthesized? Does how much we ingest have an effect on the amount in the blood? 
    It is mostly synthesized in the liver. The amount we ingest usually doesnt have an effect on how much is in the blood. 
  45. Where do the chylomicrons drain from and what does it look like?
    When they drain from the intestine they make the lymphatic vessels appear milky
  46. Where are bile salts recycled? Where are they absorbed? How are they broken down?
    They are recycled in the liver, and made available for re-use. They are sometimes absorped by the iliem. If not they will be broken down (deconjugation) and then excreted. This is a good way to get rid of excess bile salts. 
  47. What do Chylomicrons, VLDL, LDL, IDL, HDL do?
    • - VLDL, LDL, IDL carry cholesterol towards peripheral tissues. 
    • - High levels of LDL associated with increased atherosclerosis risk "bad"
    • - HDL carries cholesterol back to the liver for excretion 
    • -high levels of HDL associated with decreased atherosclerosis risk "good"
  48. What composition of LDL and HDL are present in red wine?
    It has low LDL and high HDL thus it is good for you! 
  49. Fat metabolism. Fat that is absorped from the diet?
    • - stored as fat (TG)
    • -incorportated into cell membranes (PL)
    • -oxidized as fuel in B oxidation
  50. What happens when there is excess energy?
    When there is excess lipids, carbohydrates, and amino acids they are stored as fat. Fat is a high energy store and is insoluble in water thus easy to sequester
  51. Fatty acid synthesis?
    There is four steps required to add a 2 carbon unit (malonyl CoA) to a growing fatty acid chain (elongation).

    • - Elongation
    • - Acetyl CoA is converted to Malonyl CoA (2 carbons)
    • - Malonyl CoA + fatty acid is converted to fatty acid which is 2C longer
    • - each 2 C addition requires 2 NADH and energy
  52. What is fatty acid synthase?
    • - Multifunctional enzyme
    • - Is able to carry out all 4 reactions
  53. Are animals able to saturate and unsaturate their fatty acids?
    Yes by either removing or adding hydrogen they can do both. However they can not make their own omega 3s
  54. Beta oxidation? How much ATP does it yield compared to glucose?
    • - Removal of 2 acetyl CoA units from a fatty acid to produce energy
    • – Turning a water-insoluble storage form into a water soluble TCA precursor

    -it is able to yield a huge amount compared to glucose. Fatty acid = 146 aTP and glucose = 38ATP
  55. What are the functions of lipids? 
    • • Energy
    • • Cell membrane structure
    • • Carrier of fat-soluble vitamins (absorption)
    • • Essential fatty acids
  56. Description of essential fatty acids?
    They are a required part of lipid-protein structure of cell membranes. In conjugation with other fatty acids that might not be essential 
  57. Essential fatty acids are involved with Eicosanoid metabolism (20 carbons). List some examples and functions. 
    • – Derivatives of arachidonic acid (or EPA)
    • • Thromboxanes
    • • Leukotrienes - 
    • • Prostaglandins
    • • Prostacyclins

    • - all involved in pain reception and regulation of sleep. 
    • -show hormone like action such as • Blood pressure • Smooth muscle contraction • Immune regulation • Nervous regulation • Intracellular Ca movement • Reproductive function
  58. Omega 3 fatty acids examples? Health effects?
    - Arachidonic acid C20:4(n-6), Eicosapentaenoic acid C20:5(n-3)

    • - mainly related to altered eicosanoid function
    • -long chain (20 + C) more effective than short chain. 
    • - has an effeciency of conversion
  59. What is better flax oil or fish oil
    It is a greater benefit to get omega 3 fatty acids from fish oil because they will have a greater concentration. Because as time goes on they are continually eating plants/fish that contain omega 3. 
  60. are omega 6 fatty acids as good as omega 3.
    No it takes more energy from 6 and there is a better response if they come from 3.