Flashcards in Lipids Deck (20):
Functions of lipids..?
Plants - structural & storage
Glycerol based - 1. Simple lipids - esters of fatty acids + glycerol (fats & oils) 2. Compound lipids - esters of FAs + non-lipid molecule (P, CHO, protein)
Non-glycerol based (steroids, waxes...)
Factors that determine physical properties of lipids?
Chain length & degree of saturation
Double bonds increase boiling point
Highest MP: stearic acid
Lowest MP: arachidonic acid
Properties of glycolipids?
2 alcohol groups esterified + 1 sugar residue (linoleic & linolenic) - unsaturated
What are essential FAs? Give examples.
EFAs cannot be synthesised - must be supplied in the diet eg. Linoleic & linolenic acid
EFAs needed for...?
Rich source of EFAs?
T or F - EFA deficiencies are rare in grazing animals
bile salt synonym?
What are the 4 phases of lipid assimilation?
3. Micelle formation
Briefly list steps of lipid digestion & absorption in monogastrics
1. TGs emulsified in SI by bile (duodenum)
2. Pancreatic lipases hydrolyse TGs -> monoglycerides & FFAs
3. Micelles formed by lipase & bile carry monoglycerides & FFAs -> luminal surface
4. Micelles release monoglycerides & FFAs near epithelial surface -> passive diffusion thru lipid bilayer
Major fats in grains?
TGs (mainly linoleic acid)
Major fats in forages?
galactoglycerides (mainly linolenic acid)
T or F - long chain FAs can be absorbed across the rumen
Steps in ruminant fat digestion & absorption
1. Microbial extracellular lipases hydrolyse -> glycerol, LCFAs, galactose
2. Biohydrogenation (unsaturated FAs -> saturated FAs) - > CLA -> stearic acid
Biohydrogenation of linoleic acid (glycolipid) results in...?
Formation of conjugated linoleic acid (CLA)
Fate of CLA
Most is hydrogenated to stearic acid
Some -> SI -> adipose & milk fat
Why do we care about CLA?
Inhibition of carcinogenesis
Reduction of carcass fat deposition & milk fat production
Action of dietary fat on forage digestibility?
Inhibitory action if > 5-6%
Caused by antimicrobial activity of LCFA -> reduce intake & digestibility