Lipids

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CHAPTER 10
Lipids
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Lipids
Learning Goals Know

• Biological roles of lipids
• Structure and properties of storage lipids
• Structure and properties of membrane lipids
• Structure and properties of signaling lipids
• Methods of Lipid Structure Determination

EOC Problem 1 starts off with what is a lipid
see next slide for the diversity of lipids.
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Lipids Structurally Diverse Class

• Organic molecules that are characterized by low
  solubility in water, that is, are relatively
  hydrophobic.
• Thought question would some amino acids act like
  lipids ? consider I, L, F, W, Y

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Biological Functions of Lipids

• Storage of energy
• Reduced compounds lots of available energy
• Hydrophobic nature good packing
• Insulation from environment
• Low thermal conductivity
• High heat capacity (can absorb heat)
• Mechanical protection (can absorb shocks)
• Water repellant
• Hydrophobic nature keeps surface of the organism
  dry
• Prevents excessive wetting (birds)
• Prevents loss of water via evaporation
• Buoyancy control and acoustics in marine mammals
• Increased density while diving deep helps sinking
  (just a hypothesis)
• Spermaceti organ may focus sound energy sound
  stun gun?

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More Functions

• Membrane structure
• Main structure of cell membranes
• Cofactors for enzymes
• Vitamin K blood clot formation
• Coenzyme Q ATP synthesis in mitochondria
• Signaling molecules
• Paracrine hormones (act locally)
• Steroid hormones (act body-wide)
• Growth factors
• Vitamins A and D (hormone precursors)
• Pigments
• Color of tomatoes, carrots, pumpkins, some birds
• Antioxidants
• Vitamin E

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Fatty Acid Naming Systems
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Effect of cis unsaturation on Stearic Acid 180
EOC Problem 8 Draw the structure of omega-6
fatty acid 161. You can pause here and do it !
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Fatty Acids
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Go Back to the TableLook at Melting Points
Their Meaning EOC Problem 2a and 2c Get Into
Melting Points and Unsaturation
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Glycerol Heart of Some Complex Lipids
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Triacylglycerol
When Unsatd acids are there, they are first at
C-2.
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Guinea Pig Adipocytes
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Arabidopsis Seed Section
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Sperm Whales Fatheads of the Deep
Adjusts buoyancy with Deep dives (1000m deep) by
crystallizing and becoming denserless energy is
used by the whale (to overcome buoyancy).
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Saturated and Unsaturated Fats in Food Lipids
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Trans Fatty Acids

• Trans fatty acids form by partial dehydrogenation
  of unsaturated fatty acids
• Done to increase shelf life or stability at high
  temperature of oils used in cooking (especially
  deep frying)
• A trans double bond allows a given fatty acid to
  adopt an extended conformation
• Trans fatty acids can pack more regularly and
  show higher melting points than cis forms
• Consuming trans fats increases risk of
  cardiovascular disease
• Avoid deep-frying partially hydrogenated
  vegetable oils
• Current trend reduce trans fats in foods
  (Wendys, KFC)
• EOC Problem 9 Calalytic hydrogenation of Veggie
  Oils

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Wax
EOC Problem 13 on the impermeability of waxes.
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Ear Wax (Cerumen) is Not Wax
The primary components of ear wax are shed layers
of skin 60 of the earwax consisting of
keratin 1220 saturated and unsaturated
long-chain fatty acids, alcohols and
squalene, 69 cholesterol
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Major Types of Lipids
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What X Can Be
5th Edition
Why are these arrows here?
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6th Edition
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Phosphatidylcholine

• Phosphatidylcholine is the major component of
  most eukaryotic cell membranes
• Many prokaryotes, including E. coli, cannot
  synthesize this lipid their membranes do not
  contain phosphatidylcholine

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Phosphatidyl Inositol Membrane Signaling
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Phospholipases
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Ether Lipids Plasmalogen

• Vinyl ether analog of phosphatidylethanolamine
• Common in vertebrate heart tissue
• Also found in some protozoa and anaerobic
  bacteria
• Function is not well understood
• Resistant to cleavage by common lipases but
  cleaved by few specific lipases
• Increase membrane rigidity?
• Sources of signaling lipids?
• May be antioxidants?

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Two Ether Linked aliphatic groups
High concentration in Heart Lipids
Active at 10-9 M Part of many things including
Inflammation
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Galactolipids in Chloroplasts
70-80 of Lipids in Thylakoid Membranes
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One Type of Achaea Membrane Lipid in
Hyperthermophiles
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Sphingolipids
Sphingolipids
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Discoverer of Sphingolipids
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Neuraminic Acid Sialic Acid
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Shapes of these Phospholipids
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ABO Blood Groups Glc-Gal-GalNAc-Gal Fuc
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ABO Blood Group Substances, 5th Ed
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Recycling Sphingolipids
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Membrane Lipid as Progenitor to Prostaglandins - 1
Arachidonic Acid C204?5,8,11,14
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Eicosanoids
Smooth Muscle Contraction
Hormones
Part of Blood Clotting
Asprin and Ibuprofin Inhibit Synthesis of
Prostaglandins Thromboxanes
NSAIDs Non Steroid Anti Inflammatory Drugs
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Cholesterol Steroid ( 4 fused rings)
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Steroid Hormones Made from Cholesterol
Multistep
Glucose Metabolism
Salt Excretion
Cholesterol
Anti-inflammatory
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Synthesis of Vitamin-D
Regulate Calcium Metabolism
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A child who began life in a closet
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Retinal Comes from Carotene
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Isoprene Vitamins
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Mitochondrial and Chloroplast Membrane Electron
Carriers
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Carotenoids
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Outline of Lipid Structure Identification
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Saponification and Methylation
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Gas or HPLC to separate and identify the Fatty
Acid Methyl Esters
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Mass Spectrometry of a Lipid
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A Little Review
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Things to Know and Do Before Class

1. Fatty acid properties and system of names.
2. Structures of Triacylglycerols.
3. Structures of Glycerol-Phospho-lipids.
4. Structures of Sphingolipids.
5. Progenitor of prostaglandins, thromboxanes, and
   leukotrienes arachidonic acid.
6. Cholesterol and other steroids.
7. Analysis of lipids.
8. Know how to do EOC Problems 1, 2a and c, 7-13
   and for fun (if you cook) problem 3 (works the
   same for Hollandaise sauce).