lecture 5

lipids

functions

1. stored energy

2. components in plasma membrane of all cells

3. carrier for vitamin A,D,E,K

4. insulation and lubrication

definition

plants (forage, cereals) and animals

physical

group of compounds soluble in organic solvents (ether, benzene, chloroform); insoluble in water

chemical

esters of FAs and glycerol or some other alcohol

classifications

glycerol based vs non-glycerol based

simple lipids

1. triacylglycerols

2. sterols and sterol esters

triacylglycerols (aka triglycerides)

tri-acyl esters of glycerol

most nutritionally significant of lipids group

esters of FAs w/ alcohol (glycerol)

form bulk of animal and grain/oilseed lipid

sterols and sterol esters

basic unit for all sterols including cholesterol bile acids (salts), adrenal and sex hormones (steroids)

sterols in nature

phytosterols - plant

mycosterols - fungal

zoosterols - animal (ex. cholesterol)

compound lipids

glycolipids

lipoproteins

phospholipids

lecithin

glycolipids

CHO (carbohydrate) + fat —- lipid in plants

lipoproteins

lipid + protein —- transports lipid in body

phospholipids

PO4 + lipid —- component in cell membranes

lecithin

white waxy solid

phospholipid

must abundant

secreted in bile

body store of choline, methyl donor

fatty acids

determine properties of fats and oils

natural FAs

even number of C atoms (2-24_

straight chain

carboxyl group (-COOH) at end

odd chain but only due to absorption of microbial derived FA (milk, beef)

saturated FAs

no double bonds

acetic (acetyl)

propionic (propionyl-)

butyric (butyryl-)

stearic (stearyl-)

arachidic (arachidyl-)

unsaturated FAs

double bonds (18 C)

mononenes, dienes, trienes

oilseed

mononenes

1 double bound

ex. oleic acid, elaidic acid

dienes

>1 double bond

poly-unsaturated FA

ex. linoleic acid

trienes

3 double bonds

omega-3

cis config

most FA

orientation around C—C double bond

cis=same side

trans config

formed in rumen and during processing vegetable oils

opposite side

MP of FAs

length of carbon chain (<12 C are liquid - oils, >12 C are solid - fats)

inc in double bonds, dec MP

polyunsaturated FA

3 classes

linoleic family (w-6), linolenic family (w-3), oleic family (w-9)

phospholipids

lipid transport

precursor of eicosanoids

linoleic family (w-6)

growth, fertility, maintaining skin, RBC structure

linolenic family (w-3)

strucutre and function of eye and CNS

oleic family (w-9)

not abundant but can be made in body under conditions of essential fatty acid deficiency

fatty liver disease

common in overweight non-ruminant animals

hepatocyte filled with triacylglycerol

essential FAs

can’t synthesize sufficient quantities supplied in diet

corn oil + linseed oil, large effect

linoleic (dogs + cats)

FA defficiency

hair loss

scaly dermatitis

skin necrosis

unthrifty appearance

absorbed FA in body

organs remove and use rapidly

1. muscle, heart, liver

2. adipose tissue

3. mammary gland