L10: Lipids Flashcards
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)
_*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
_*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
*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
What is glycerol?
The alcohol component of all triglycerides
*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)
_*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)
What is a glycolipid?
- 2 alcohol groups of glycerol esterified and third is linked to a sugar residue
*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
*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
*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)
- Hydrolysis
- Micelle formation
- Absorption**
*Describe the process of fat digestion & absorption in monogastrics
Draw or explain diagram
*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
*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
Describe the process of fat digestion and absorption in ruminants
draw flow chart
