Sukalski lipids11complete with metabolism much detail
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This document outlines the key objectives and content to be covered in a lecture on lipids. It will discuss the structures of common fatty acids, how fatty acid chain length and saturation affect melting point. It will also define triglycerides, phospholipids, and the sites of action and products of phospholipases. The roles of pancreatic lipase, phospholipases, and bile acids in digesting and absorbing lipids will be explained. Finally, it will discuss why specialized lipoprotein particles are necessary to transport triglycerides and cholesterol in the bloodstream.
Sukalski lipids11complete with metabolism much detail
- 1. Lipids 1 Dr. K. A. Sukalski February 25, 2002
- 2. Objectives Know the common names and structures of the following fatty acids: • C16, C16:1 • C18, C18:1, C18:2, C18:3 • C20:4 Understand the relationship between fatty acid chain length, unsaturation and melting point. Recognize a TAG, MAG, and DAG (triacylglycerol, monoacylglycerol, diacylglycerol). Recognize a phospholipid. You will not need to be able to differentiate among the different kinds of phospholipids.
- 3. What are the sites of action and products of the phospholipases A1, A2, C, and D? Define amphipathic (amphiphilic means the same thing) (see textbook). What are the main lipid components of the average diet? Understand how the actions of pancreatic lipase, phospholipase and bile acids (same as bile salts for our purpose) contribute to the digestion and absorption of lipid. What happens to the absorbed products of dietary lipid inside the intestinal cell? Know the basic composition of chylomicrons. Why is a special, complicated mechanism of transporting TAGs and cholesterol in the blood necessary? What is this mechanism?
- 4. Major Macromolecules Carbohydrates Proteins Nucleic Acids Lipids
- 5. Fig 9.1 Structural relationships of major lipid classes Signals Energy Structure
- 6. Most Important Lipids: My Choice Fatty Acids – oxidized for energy – building blocks for TAGS and PL – precursors to hormones - Eicosenoids Triacylglycerols - TAGS – storage form of fatty acids which are used for energy Phospholipids – PLs – For membranes Cholesterol
- 7. This is a fatty acid. Amphipathic – contains both polar and nonpolar parts Even Number of carbons Melting Point chain length saturation (=) Nomanclature: C1, α, β, ω Figure 9-2 p. 266
- 8. Table 9.1 Note: oleate = oleic acid stearate = stearic acid
- 9. Saturated vs Unsaturated Fatty Acids C18 stearate C18:1 oleate C18:3 linolenate MP = 70 MP = -17 MP = 13
- 10. Triacylglycerols: a Family with Many Members Note these are very hydrophobic!!! More so than the fatty acids from which they are made Energy Storage
- 11. Glycerolphos-pholipids Amphipathic!!! Membrane Components
- 12. Fig 9.9 Phospholipases hydrolyze phospholipids PLase A1 or A2 gives a lysophospholipid (lacking a fatty acid) PLase C gives a diacylglycerol PLase D gives a phosphatidate
- 13. Other Classes of Lipids Lipids Important in Membrane Structure – Sphingolipids (Fatty acids and Carbohydrates) – Steroids, especially cholesterol Specialized functions – Waxes – Prostaglandins
- 14. Lipid Metabolism Chapter 16
- 15. Chapter 16 Fatty Acids – oxidized for energy – building blocks for TAGS and PL – precursors to hormones - Eicosenoids Triacylglycerols - TAGS – storage form of fatty acids which are used for energy
- 16. Composition of Lipid in the Diet 90% TAGs PLs Cholesterol
- 17. Digestion and Absorption of Dietary Lipids We have a problem. – Think “oil and water” or “cutting a cow from a herd” How do we get from large fat globules to small molecules which can be absorbed across the intestinal cell?
- 18. Break the hydrophobic TAGs down to a monoacylglycerol + 2 fatty acids Break Phospholipids down to lysophospholipid and a fatty acid Coat the particles with amphipathic molecules (bile salts or bile acids) to make micelles – hydrophobic part meshes with the lipid – hydrophilic part presents to the water compartment
- 19. Fig 16.2 Action of pancreatic lipase
- 20. Fig 16.3 Dietary phospholipids are degraded by phospholipases
- 21. Fig 16.1 Bile salts are amphipathic derivatives of cholesterol and amino acids. • Taurocholate and glycocholate (cholesterol derivatives) are the most abundant bile salts • Amphipathic: hydrophilic (blue), hydrophobic (black) Synthesized in Liver Stored in gall bladder Secreted into intestine Forms micelles
- 22. Absorbed from Micelles Monoacylglycerol Free fatty acids Lysophospholipids Cholesterol
- 23. In the Intestinal Cell monoacylglycerol + 2 fatty acids-- TAGs cholesterol + fatty acid -- cholesterol ester lysophospholipid + fatty acid -- PL apolipoprotein B And we have a special kind of lipoprotein called a chylomicron to transport lipids around the body
- 24. Why Do We Need Lipoprotein Particles to Transport Lipid? Solubility of cholesterol as an example of functional importance of lipoprotein particles. 0.2 mg/dL in water at 250. 150 – 200 mg/dL in plasma 30% free 70% esterified In Bile: Bile salts and phosphatidyl- choline maintain cholesterol in solution. 390 mg/d: in bile 96% free 4% esterified
- 25. Fig 16.5 Structure of a lipoprotein
- 26. Fig 16.6 Summary of lipoprotein metabolism Lipoprotein Lipase
- 27. Major Classes of Lipoprotein Particles