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Flashcards in Lipids Deck (20):
0

Functions of lipids..?

Carrier molecules
Vitamin absorption
Membrane structures
Energy stores
Plants - structural & storage

1

Lipid classes?

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...)

2

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

3

Properties of glycolipids?

2 alcohol groups esterified + 1 sugar residue (linoleic & linolenic) - unsaturated

5

What are essential FAs? Give examples.

EFAs cannot be synthesised - must be supplied in the diet eg. Linoleic & linolenic acid

6

EFAs needed for...?

membranes
lipid transport
enzymes
prostaglandins

7

Rich source of EFAs?

oilseeds

8

T or F - EFA deficiencies are rare in grazing animals

true

9

bile salt synonym?

amphipath

10

What are the 4 phases of lipid assimilation?

1. Emulsification
2. Hydrolysis
3. Micelle formation
4. Absorption

11

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

12

Major fats in grains?

TGs (mainly linoleic acid)

13

Major fats in forages?

galactoglycerides (mainly linolenic acid)

14

T or F - long chain FAs can be absorbed across the rumen

false

15

Steps in ruminant fat digestion & absorption

1. Microbial extracellular lipases hydrolyse -> glycerol, LCFAs, galactose
2. Biohydrogenation (unsaturated FAs -> saturated FAs) - > CLA -> stearic acid

16

Biohydrogenation of linoleic acid (glycolipid) results in...?

Formation of conjugated linoleic acid (CLA)

17

Fate of CLA

Most is hydrogenated to stearic acid
Some -> SI -> adipose & milk fat

18

Why do we care about CLA?

Inhibition of carcinogenesis
Reduction of carcass fat deposition & milk fat production

19

Action of dietary fat on forage digestibility?

Inhibitory action if > 5-6%
Caused by antimicrobial activity of LCFA -> reduce intake & digestibility

20

How can the effects of antimicrobial LCFA be overcome?

Add calcium hydroxide to diet -> immobilises LCFA