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Lipids (fats)

Lipids (fats). Ooh, totally aliphatic!. Lipids characteristics. Efficient storage of energy !!! Nonpolar or low polarity Many have a polar end (hydrophilic) and a nonpolar end (hydrophobic) = amphipathic molecules Insoluble in water Two major groupings: Hydrolyzable Nonhydrolyzable.

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Lipids (fats)

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  1. Lipids (fats) Ooh, totally aliphatic!

  2. Lipids characteristics • Efficient storage of energy !!! • Nonpolar or low polarity • Many have a polar end (hydrophilic) and a nonpolar end (hydrophobic) = amphipathic molecules • Insoluble in water • Two major groupings: • Hydrolyzable • Nonhydrolyzable

  3. Fatty acids in nature: • Saturation: • Saturated • Unsaturated • Monounsaturated • Polyunsaturated • Usually cis • Number of carbons are even • Linear molecules: not branched

  4. Omega number (ω) • This indicates how many carbons from the far end of the fatty acid to the first double bond • ω-1 is the methyl group at the end farthest from the COOH group • The omega number of linoleic acid would be ____

  5. Effect of saturation on melting points • Examine the chemical structures on the next slide. • How well would a saturated chain pack into a solid compared to an unsaturated chain? • Influence on melting point:

  6. Melting points of fatty acids • Animal fats are generally ________ at room temperature • Vegetable fats are generally ________ at room temperature • Which do you expect have more double bonds?

  7. Most of our animal fat and plant oil intake is triacylglycerols; get hydrolyzed and absorbed in gut, then reassembled: energy storage A major membrane lipid component: note hydrophilic end of molecule Another major membrane lipid: note hydrophilic end of molecule again! Another membrane lipid, but note saccharide attachment: think cell-recognition ie blood groups?

  8. Triacylglycerols • One glycerol + three fatty acids = one triacylglycerol • Triple esterification • Reverse is hydrolysis (3x over) • Base hydrolysis of triacylglycerol → soap (saponification) • Catalytic hydrogenation of unsaturated fats • Unsaturated triacylglycerol → saturated triacylglycerol • Alkene → alkane • Triacylglycerol = triglyceride • Energy source; energy reserves for the future

  9. Steroids: note the core ring structure of these molecules All steroids have this basic unit, although sometimes it is a little disguised

  10. Steroids • Cholesterol • Incorporated in cell membranes • Precursor to other animal steroids • Body can synthesize all it needs even if cholesterol is completely removed from the diet. It’s that important.

  11. Steroid hormones • Need only very low concentrations • Adrenals: • Cortisol (fight or flight) • Aldosterone (regulate electrolytes in blood) • Sex hormones • Chemical messengers and regulation of cell functions

  12. Vit D can be named as a cholesterol derivative – do you see the relationship?

  13. Vitamin D biosynthesis – notice compartmentation (location) of different steps

  14. Just to see these two drawn out to full chain length:

  15. Eicosanoids: Eicosane = ________ Eicosanoids are involved in:

  16. Membranes: • Optimal proportions of • Lipids • Proteins • Cholesterol • for strength and function • of that type of cell

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