lipids water insoluble (hydrophobic) non-polymeric structure energy storage, membrane constituent,...
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Lipids
Water insoluble (hydrophobic)
Non-polymeric structure
Energy storage, membrane constituent, hormone signaling
Migrate over-water 2,400 miles
I. Fatty Acids: Fuel & Membrane Building BlocksHydrocarbon with carboxylic acid head group
Highly reduced carbon source
Ionized at neutral pH (-ate not -ic acid form)
Which fatty acid is more reduced?
What makes soap a good cleaner?
Soap: fatty acid salt Soap: fatty acid salt
Naturally Occurring Animal Fatty Acids: Common and Systemic Names
Melting Point and Membrane Fluidity
Shorter chain length lowers melting point
cis Double bond lowers melting point
Unsaturated fatty acids (oils) lower melting point versus saturated fatty acids (solid)
Predict the oil composition from palm versus canola plants.
Health Versus Fat Quantity and Quality
Trans fats correlated with high blood cholesterol/cardiovascular disease (inflammation?)
Cis polyunsaturated fatty acids essential for the diet (inhibit blood clotting, reduce heart attack risk)
Vegetable oil (linolenate)
Shell fish/cold water fish (EPA/DHA)
II. Triacylglycerol in Energy StorageAnhydrous fat /gram stores 6x energy of hydrated glycogen
Triacylglycerol storage site – adipose tissue
Sugar storage 18 hrs; triacylglycerol storage several weeks
III. Phospholipids: Major Class of Membrane Lipids
Phosphatidate: key intermediate in phosphoglyceride biosynthesis and membranes
Lipid bilayer
Common Membrane Phosphoglycerides
What does the color coding for green, blue and pink represent?
Membrane Sphingolipids
Amino alcohol backbone – sphingosine
Sphingomyelin –sphingosine with a fatty acid amide linkage and choline; abundant in nerve cell membranes
Cerebroside – sphingosine with a sugar residue (aka glycolipid)
IV. Glycolipids
Gangliosides – sphingosine with multiple sugar residues
Sugars are extracellular
A, B and O blood typing
Multiple sugar units
V. Steroids
How does cholesterol orientate in the membrane?
Tetracyclic ring structure (3 cyclohexane fused with cyclopentane)
Facilitate lipid digestion
Membrane fluidity buffer
LipoproteinsProtein attachment to the surface of a membrane
N-Myristoylglycine
Membrane Component from a High-Temperature Organism
What are the chemical differences in this lipid from standard membrane lipids?
What impact do these alterations have on lipid behavior?
Phospholipids and Glycolipids Self-Assemble to Form a Lipid Bilayer
Driving Forces:
• H-bonding
• Hydrophobic effect
• Electrostatic interactions
• Van der Waal’s attractions (close packing)
Membrane Fluidity: Temperature, Cholesterol and Fatty-Acid-Composition Regulated
How does membrane composition alter with elevated temperature?
Significant Lateral Albeit Minimal Transverse Lipid Movement
Liposome for Potential Drug Delivery
Lipid Bilayer Small-Molecule Permeability
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* * *
Unassisted membrane crossing linked with H2O and non-polar solvent solubility
* Protein assisted transport
Peripheral and Integral Membrane Proteins
What tethers peripheral proteins to the membrane?
What secondary structure is common in membrane hydrophobic regions?
Different membrane orientation (a and e), surface position (f and e) and membrane componentassociation (d, and g)
Alpha Helices in the Integral Protein Bacteriorhodopsin
Bacteria light-harvesting protein that generates proton gradient
α-Helix most common 2° membrane structure
Helical (yellow) and charged (red) residues
Chapter 8 Problems: 1, 3, 5, 7, 9, 19, 21, 23 and 25