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Lipids: Fats & Oils

Lipids, essential molecules composed of C, H, O, include fats, phospholipids, steroids, serving as a concentrated energy source. Learn about their structure, functions, and significance in cellular membranes. Explore saturated and unsaturated fats, phospholipids' dual nature, and the role of cholesterol in cell membranes.

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Lipids: Fats & Oils

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  1. Lipids: Fats & Oils

  2. long term energy storage concentrated energy Lipids

  3. Lipids • Lipids are composed of C, H, O • long hydrocarbon chains (H-C) • “Family groups” • Fats (triglycerides) • phospholipids • steroids • Do not form polymers • big molecules made of smaller subunits • not a continuing chain

  4. enzyme H2O Fats • Structure: • glycerol (3C alcohol) +fatty acid • fatty acid = long HC “tail” with carboxyl (COOH) group “head” dehydration synthesis

  5. Building Fats • Triacylglycerol • 3 fatty acids linked to glycerol • ester linkage = between OH & COOH hydroxyl carboxyl

  6. enzyme enzyme enzyme H2O H2O H2O H2O Dehydration synthesis dehydration synthesis

  7. Why do humanslike fatty foods? Fats store energy • Long HC chain • polar or non-polar? • hydrophilic or hydrophobic? • Function: • energy storage • concentrated • all H-C! • 2x carbohydrates • cushion organs • insulates body • think whale blubber!

  8. Saturated fats • All C bonded to H • No C=C double bonds • long, straight chain • most animal fats • solid at room temp. • contributes to cardiovascular disease (atherosclerosis) = plaque deposits

  9. Unsaturated fats • C=C double bonds in the fatty acids • plant & fish fats • vegetable oils • liquid at room temperature • the kinks made by doublebonded C prevent the molecules from packing tightly together mono-unsaturated? poly-unsaturated?

  10. Saturated vs. unsaturated saturated unsaturated 

  11. Phospholipids • Structure: • glycerol + 2 fatty acids + PO4 • PO4 = negatively charged It’s just like apenguin… A head at one end & a tail at the other!

  12. Phospholipids • Hydrophobic or hydrophilic? • fatty acid tails = • PO4 head = • split “personality” hydrophobic hydrophillic “attracted to water” Come here,No, go away! Come here,No, go away! interaction with H2O is complex & very important! “repelled by water”

  13. Phospholipids in water • Hydrophilic heads “attracted” to H2O • Hydrophobic tails “hide” from H2O • can self-assemble into “bubbles” • bubble = “micelle” • can also form a phospholipid bilayer • early evolutionary stage of cell? water bilayer water

  14. Why is this important? • Phospholipids create a barrier in water • define outside vs. inside • they make cell membranes!

  15. Steroids • Structure: • 4 fused C rings + ?? • different steroids created by attachingdifferentfunctional groups to rings • different structure creates different function • examples:cholesterol, sex hormones cholesterol

  16. Cholesterol • Important cell component • animal cell membranes • precursor of all other steroids • including vertebrate sex hormones • high levels in blood may contribute to cardiovascular disease

  17. Cholesterol helps keep cell membranes fluid & flexible Important component of cell membrane

  18. From Cholesterol  Sex Hormones • What a big difference a few atoms can make!

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