Bmsc Lipids

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Bmsc Lipids
2012-11-30 12:13:38
bmsc chapter 10 lipids

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  1. Functions of Lipids
    • energy storage (fat in animals, oils in plants)
    • structural component of membranes
    • active roles (signalling, enzymes cofactors+pigments)
  2. States of Lipids
    • -lipids have a low oxidation state, giving 9 kcal per gram
    • -low hydration state, provides compact, dehydrated energy form
  3. 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)
  4. 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
  5. 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
  6. 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)
  7. 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
  8. waxes
    • -waxes are nonpolar esters of long chain fatty acids and long chain monohydroxilic alcohols
    • -very water insoluble
    • -high melting temp (60-100 celsius)
  9. 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
  10. 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
  11. Sulfolipids
    • -same as galactolipids, but use sulfonate group instead for hydrophilic head
  12. 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
  13. 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
  14. 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
  15. 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
  16. Cholesterol
    • -mediate membrane fluidity (remember his concert stage setup metaphor)
    • -precursor for steroid hormones and bile salts
    • -cardiovascular disease linked
  17. 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)
  18. 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
  19. Vitamin D
    • -synthesized from 7-dehydrocholesterol in a series of reactions, one involves sunlight
    • -rickets is deficency disease (alters growth pattern)
  20. 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
  21. Vitamin E
    • -reducing reagent that scavenges oxygen free radicals (gets rid of free radicals) therfore considered antioxidant
    • -deficiency causes scaly skin, weakness and sterility
  22. 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)