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Functions of Lipids
- energy storage (fat in animals, oils in plants)
- structural component of membranes
- active roles (signalling, enzymes cofactors+pigments)
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States of Lipids
- -lipids have a low oxidation state, giving 9 kcal per gram
- -low hydration state, provides compact, dehydrated energy form
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Structure of fatty acids
- -hydrocarbon with carboxylic head
- -usually even number of carbons
- -can be saturated, mono-poly unsaturated (typically cis double bonds)
- -conjugated double bonds rare (where it alternates between single and double bonds, we know they are generally 3 carbons apart in nature)
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Fatty Acid Nomenclature
- -carboxyl group carbon is carbon number 1
- -then put a : and total number of double bonds
- -in BMSC use a delta and then superscript the location of all double bonds 18:3Δ9,12,15 would be alpha linolenic
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Interaction Forces
- -only use hydrophobic and van der waals, with hydrophobic being stronger
- -shorter chains or more double bonds are more likely to be liquid
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Triacylglycerols=Triglycerides from nutrition
- -storage form of lipids in plants and animals
- -simpler ones have same fatty acid at each position, more complex have different ones
- -removing the ester linkage will make more hydrophobic molecule (removing fatty acid tails from glycerol backbone)
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Olestra
- -eight fatty acids linked to a sucrose
- -same taste and texture as fat but you dont absorb it, just shit it out
- -not approved in canada
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waxes
- -waxes are nonpolar esters of long chain fatty acids and long chain monohydroxilic alcohols
- -very water insoluble
- -high melting temp (60-100 celsius)
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Glycerophospholipids
- -most abundant lipids in membranes
- -like normal triglyceride, except where the third fatty acid normally goes it is a phosphate
- -glycerol-3-phosphate+ 2 fatty acids=phosphatidate
- -C1 fatty acid usually 16 or 18 carbons and saturated
- -C2 fatty acid usually 18 or 20 carbons and unsaturated
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Galactolipids
- -only found in plant cells
- -one or two galactose molecules linked to C3 position of diacylglycerol
- -plants are usually low in phosphate, thats why they use an equivalent hydrophilic group

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Sulfolipids
 - -same as galactolipids, but use sulfonate group instead for hydrophilic head
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Ether Linked Fatty Acids
- -sometimes fatty acids can be linked by an ether linkage rather than esther linkage
- -more chemically stable and resistant to digestion by lipases

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Sphingolipids
- -single fatty acid joined by amide bond to form ceramie
- -3 classes of sphingolipid, have different polar head group
- 1-sphingomyelins
- 2-cerebrosides=glycosphingolipid with single sugar unit
- 3-ganglioside=glycoshpingolipid with more than 6 sugar units
 - pink part it sphingosine, yellow is fatty acid and blue X is where it varies
- -different blood types are glycosphingolipids where the X varies
- -sphingolipids are broken down in lysosomes by different lipases
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Extremophile Membranes
- -some extremophile archeabacteria live in high temp of pH environments that would force a lipid bilayer apart
- -in these extreme conditions the bilayer is actually just a single long chain hydrocarbon with glycerol head groups on both ends so it cant pull apart
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Steroids
- -steroids=sterols
- -structural membrane lipids
- -precursors for many biologically active products
- -four fused ring system with 3 6 carbon rings (A,B,C) and one 5 carbon ring (D)
- -ring system is rigid and nearly planar

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Cholesterol
- -mediate membrane fluidity (remember his concert stage setup metaphor)
- -precursor for steroid hormones and bile salts
- -cardiovascular disease linked
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Eicosanoids
- -paracrine hormones (act on cells near point of production)
- -derivatives of C20 PUFA (arachidonic acid)
- 3 Classes
- -Prostaglandins-constriction of blood vessels
- aspirin blocks production of prostaglandins
- -Thromboxanes-blood clot formation, aspirin also blocks their creation
- -Leukotrienes-smooth muscle contraction/bronchial constriction(asthma)
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Steroids as message carriers
-hydrophobic steroid derivatives carried by carrier proteins through bloodstream and pass through plasma membrane and bind to receptors in nucleus, this alters patterns of gene expression and metabolism
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Vitamin D
- -synthesized from 7-dehydrocholesterol in a series of reactions, one involves sunlight
- -rickets is deficency disease (alters growth pattern)
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Vitamin A
- -from liver, egg yolks, milk, or green/orange veggies
- -3 forms=retinol(alcohol), aldehyde, and retinoic acid
- -retinal aldehyde has role in vision
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Vitamin E
- -reducing reagent that scavenges oxygen free radicals (gets rid of free radicals) therfore considered antioxidant
- -deficiency causes scaly skin, weakness and sterility
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Vitamin K
- -used in blood coagulation proteins
- -vitamin K analogs (look alikes kinda) are given to people who suffer excess blood clotting, they act as competitive inhibitor to vitamin K, and are known as blood thinners (warfarin)
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