Stearic acid (C18)

Oleic acid

fatty acids

ALAEssential 3

tight packing

less stable aggregates (lower melting point)

Adipocytes showing huge fat droplets that virtually fill the cells

cotyledon cell from a seed

It contains a complex mixture of lipid that is liquid (less dense) at 37°C, begin to cristallize at 31°C and it is solid (more dense) below 31°C

Fatty acid composition of three food fats

Many fast foods are deep-fried in partially hydrogenated vegetable oils and therefore contain high levels of trans fatty acids

Triacontanoylpalmitate

waxes

Ester bond

L-Glycerol 3-phosphate, the backbone of phospholipids

Glycerophospholipids

Glycerophospholipids

Ether lipids

Hethanolammine

choline

Ether lipids

Sphingolipids

similarities in shape and molecular structure of phosphatidylcholine (a glycerophospholipid) and sphingomyelin (a sphingolipid) are clear when their space-

filling and structural formulas are drawn as here.

similarities in shape and molecular structure of phosphatidylcholine (a glycerophospholipid) and sphingomyelin (a sphingolipid) are clear when their space-filling and structural formulas are drawn as here.

The polar head of many gangliosides

Glycosphingolipids as determinants of blood groups

The specificities of phospholipases

Phospholipids and Sphingolipids Are Degraded in Lysosomes

Pathways for the breakdown of GM1, globoside, and sphingomyelin to ceramide. A defect in the enzyme hydrolyzing a particular step is indicated by the partial breakdown product is noted.

Ceramide

Sphingosine

Growth arrestApoptosis

Proliferation

IMPORTANT ALSO FOR SKIN STRUCTURE AND FUNCTION

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Necrosis: a pathological responseto cellular injury

Apoptosis: a physiological response to specific suicide signals,

or lack of survival signals

Chromatin clumps

Chromatin condenses and migrates to nuclear membrane. Internucleosomal cleavage leads to

laddering of DNA at the nucleosomal repeat length, ca. 200 bp.

Mitochondria swell and rupture Cytoplasm shrinks without membrane rupture

Plasma membrane lyses Blebbing of plasma and nuclear membranes

Cell contents spill outCell contents are packaged in membrane bounded bodies, internal organelles still functioning, to be

engulfed by neighbours.

General inflammatory response is triggeredEpitopes appear on plasma membrane marking cell

as a phagocytic target.No spillage, no inflammation

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Sphingolipids• Contain sphingosine, a long-chain amino

alcohol

• Found in plants and animals

• Abundant in nervous system

• Has structural similarity to phospholipids– Ceramide tells cells to undergo apoptosis– Sphingosine tells cells to grow, divide

and migrate Remove Phosphoethanolamine

cholesterol

A fatty acid is esterifiedFor storage ortransport

detergents in the intestine

Glycerophoepholipid that act as intracellular messengers

Arachidonic acid

Eicosanoids Carry Messages to Nearby Cells

Arachidonic acid is the precursor of eicosanoids, including the prostaglandins, thromboxanes, and leukotrienes.

PROSTAGLANDINS

stimulate contraction of the smooth muscle during menstruation and labor

Affect blood flow and wake-sleep cycle

Affect responsiveness to hormones

TROMBOXANES

Produced by plateletes, are involved in blood clot formation

Affect blood flow

LEUKOTRIENES

stimulate contraction of smooth muscles

Steroids derived from cholesterol

Many of the plant volatiles are derived from isoprene

Cholesterol is made from acetyl-CoA

• Mevalonate formation is

the first stage of cholesterol

synthesis

Mevalonate is converted to isoprene-containing molecules

• Isoprenoids are

precursors for several

important biomolecules

Vitamin D production

Vitamin A1 and its precursor and derivatives