1. Classes of Lipids fatty acids Fat soluble vitamins eicosanoids *
steroids
triacylglycerols
glycolipids
*waxes
phospholipids
* fatty acids absent

2. Functions Energy source Hydrophobic barriers Functional
storage compounds (triacyl glycerols)
Hydrophobic barriers
membrane constituents (phospholipids & glycoplipids)
Functional
protective coverings (waxes)
regulatory properties e.g. coenzymes
hormones (steroids, prostaglandins,vitamins)
signalling e.g. odours

3. 1.FATTY ACIDS General structure
Ionised at pH7 amphipathic O O
hydrophilic carboxyl group C
hydrophobic hydrocarbon chain

4. Aggregates of Fatty Acids
Hydrophobic tail
Surface film
Hydrophilic head
micelle
water

5. SATURATED FATTY ACIDS Typical example:stearic acid Sat FA
Highly flexible - free rotation around each C-c bond.
Pack together tightly in near crystalline array along their length.
VW contact with neighbouring mols.
Diag Lehninger p242
Mp increase with molecular mass
Typical example:stearic acid

6. MONOUNSATURATED FATTY ACIDS e.g. OLEIC ACID - 18:1
Unsat FA
Unsat common -
1. Monounsat
polyunsat up to 6 double bonds per chain.
Triple bonds rare.

7. POLYUNSATURATED ACIDS
LINOLEIC ACID - 18:2
Both bonds are cis

8. Acid name Symbol Function
Mp C
63.1
-0.5
69.6
13.4
Acid name Symbol Function
Butyric 4:0 Occur Capric in milk
Palmitic * Structural
Palmitoleic 16.1(9) lipids and
Stearic triacylglycerols
Oleic acid* 18.1(9)
Linoleic* essential fatty Linolenic acids
Arachidonic 20:4(5,8,11,14) Precursor of prostaglandins
Lignoceric 24:0 Components of
Nervonic 24.1(15) cerebrosides
* predominant fatty acid residues in cells

9. Link between metabolism of carbohydrates, fats and amino acids
Sugars
glycolysis
TCA Cycle
AcetylCoA
Pyruvate
AcetylCoA
Palmitic acid 16.0
Elongation
Desaturation
Amino acids
mitochondrion
Various Fatty Acids

10. Synthesis of Fatty Acids: 2 carbon additions
Palmitate 16.0
elongation
Stearate 18.0
desaturation
Oleate 18.1(9)
Linoleate (9,12)
Arachidonate 20.4 ( )
Linolenate 18.3 (9,12,15)
Other poly unsaturated FA
EICONASOIDS

11. General formula CH3 (CH2) nCOO Amphipathic Structure
Fatty acids: Summary
General formula CH3 (CH2) nCOO
Amphipathic
Structure
C (biological)
unsaturated / mono or polysaturated
cis configuration
branching simple
Rarely free
Alkyl chain+ terminal carboxylic group
Usually even no C atoms or 20 common. Long chains in nervous system e.g. C double bonds in nervonic acid. .
Unsat common - up to 6 double bonds per chain.
Triple bonds rare.
Numerical system indicates structure (p364)
A few have alpha-OH group. More oxidised forms only produces duringenergy production or specific physiol cases e.g. prostaglandins.
Branching simple, limited to methyl groups. E.g. isovaleric acid in echo-locating structures of mammals.
Free FA have free -COOH and circulate in the blood bound to serum albumin.
But Most occur as esters of glycerol or amides. Lacking the carboxylate group they are less soluble then FA = stored for future use.

12. TRIACYLGLYCEROL

13. Adipocyte cytoplasm triacylglycerol nucleus 10μm Energy store
Lipases in adipocytes and germ seeds break down TAG, releasing FA for export and fuel.
Advantage as store cf- polysac.
1.C more reduced
Oxidation gives twice as much energy per g as carbs.
2.Hydrophobic so organism does not need to carry weight of water of hydration assoc with stored polysacs.
3.Mols cluster - adopt position of minimal contact with aq surroundings - cannotparticipate in formation of membranes
Human - glycogen store = 6 h, although quick source of energy.
Fat tissue (adipose under skin, in abdominal cavity and mammary glands)
Obese = kg TAG in adipocytes. - can supply energy need for months.
nucleus

14. Sperm Whale
Spermaceti organ