L10: Lipids Flashcards Preview

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Flashcards in L10: Lipids Deck (16)
1

What is a lipid? Describe incl. functions

  • Fat baby fat!!!
  • [ ] energy source
  • any of a class of organic compounds that are fatty acids or their derivatives and are insoluble in water but soluble in organic solvents
  • Simple lipids (fats/oils) comprised of glyerol b.bone and fatty acids
  • organic compounds insoluble in water
  • Functions (animals):
    -carriers (electrons & substrates)
    -vitamin absorption
    -biological membranes
    -energy stores
  • Functions (plants):
    -structural (membranes, protective layers)
    -storage (oil in seeds/fruit)

2

*Describe how lipids can be classified
(can be simple, compound or non-glycerol based)

Describe simple lipids?

  • fats and oils are esters of FA w/ glycerol
  • glycerol b.bone w/ 1-3 FA attached
     

3

*Describe how lipids can be classified
(can be simple, compound or non-glycerol based)

Describe compound lipids?

  • Esters of FA's containing non-lipid substances
  • P, S, CHO, AA and proteins
  • phospholipids (picture)
  • glycolipids
  • lipoproteins
  • phosphoglycerides
     

4

*Describe how lipids can be classified
(can be simple, compound or non-glycerol based)

name some non-glycerol based lipids?

  • sphingomyelins
  • waxes
  • steroids
  • eicosanoids
  • cerebrosides

5

What is glycerol?

The alcohol component of all triglycerides

 

6

*Describe factors affecting the physical properties of lipids    

What are fatty acids?

  • Chains of C atoms w/ carboxyl group on end of each chain
  • General formula RCOOH, where R is C chain
  • Can be unsaturated (due to double bonds)
  • or saturated (no double bonds)

7

*Describe factors affecting the physical properties of lipids

(mono, di and tri saccherides)

  • Chain length and degree of unsaturation of FA's determine properties
  • Usually have an even number of C atoms, a single COOH, and an unbranched C chain
  • FA w/ more than one DB called poly unsaturated fatty acids (PUFA)

8

What is a glycolipid?

  • 2 alcohol groups of glycerol esterified and third is linked to a sugar residue

9

*Define what is meant by the term ‘essential fatty acid’ and give examples 

 

  • Must be supplied in diet
  • Linoleic and linolenic acid cannot be synthesised by animals
  • Arachidonic can be synthesised from linoleic, but slowly
  • Needed for membranes, lipid transport, enzymes, and prostaglandins
  • Oilseeds are rich source
  • Deficiencies rare in grazing animals, intensively kept animals at risk

10

*Describe the process of fat digestion & absorption in monogastrics 

What is the function of bile salts and pancreatic lipase?

  • Bile salts emulsify fats leaving the stomach
  • known as amphipaths (have polar/nonpolar; charged/uncharged sides)
    -aggregate together to form micelles
  • Pancreatic lipase hydrolyses triglycerides to monoglyc. and free FA
     

11

*Describe the process of fat digestion & absorption in monogastrics 

Where does the digestion of lipids occur?

Describe the 4 phases of lipid assimilation

  • digestion of lipids occurs in SI, by action of pancreatic lipase
  • must undergo emulsification by bile salts before they can be digested by water soluble lipase
  • 4 phases of assimilation:
    -1. emulsification (by bile salts)
    -2. Hydrolysis
    -3. Micelle formation
    -4. Absorption


     

12

*Describe the process of fat digestion & absorption in monogastrics 

Draw or explain diagram

13

*Describe the process of fat digestion and absorption in ruminants 

Major fats in grains are...?

Major fats in forages are...?

lipid digestion in ruminant is done by...?

Long chain fatty acids cannot be absorbed across rumen... T or F?

  • Major fat in grains are TGs
    -contain high proportion if linoleic acid
  • in forages are galactoglycerides
    -high proportion or linolenic
  • lipid digestion done by microbes
    -microbial extracellular lipases hydrolyse to glycerol and FFA (plus galactose)
    -glycerol and galactose metabolised by microbes
  • T

14

*Describe the process of fat digestion and absorption in ruminants 

Describe biohydrogenation
 

  • Addition of a H ion to remove a double bond (saturate)
  • Unsaturated FFA biohydronated by bacteria
  • 1st step in BHDN of linoleic acid, conjugated linoleic acid (CLA) is formed
    -Most CLA hydrogenated to stearic acid
    -CLA of particular interest due to range of biological activities incl inhibition of carcinogenesis

15

Describe the process of fat digestion and absorption in ruminants 

draw flow chart

16

Describe the process of fat digestion and absorption in ruminants 

Describe the relationship between dietary fat and rumen microbes

  • Inhibitory action of DF on forage digestibility
    -if fat in diet greater than 5%, -ve effect on microbe activity
  • Caused by antimicrobial activity of surface-active LCFA libertaed by lipolysis in rumen
  • Effect can be overcome by adding calcium hydroxidw to diet