Biochemistry:%20A%20Short%20Course

1
Lipids
Migrate over-water 2,400 miles
Water insoluble (hydrophobic) Non-polymeric
structure Energy storage, membrane constituent,
hormone signaling
2
I. Fatty Acids Fuel Membrane Building Blocks
Hydrocarbon with carboxylic acid head
group Highly reduced carbon source Ionized at
neutral pH (-ate not -ic acid form)
Soap fatty acid salt
Which fatty acid is more reduced? What makes
soap a good cleaner?
3
Naturally Occurring Animal Fatty Acids Common
and Systemic Names
4
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.
5
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)
6
II. Triacylglycerol in Energy Storage
Anhydrous fat /gram stores 6x energy of hydrated
glycogen Triacylglycerol storage site adipose
tissue Sugar storage 18 hrs triacylglycerol
storage several weeks
7
III. Phospholipids Major Class of Membrane Lipids
Phosphatidate key intermediate in
phosphoglyceride biosynthesis and membranes
Lipid bilayer
8
Common Membrane Phosphoglycerides
What does the color coding for green, blue and
pink represent?
9
Membrane Sphingolipids
Amino alcohol backbone sphingosine Sphingomyel
in sphingosine with a fatty acid amide linkage
and choline abundant in nerve cell membranes
Cerebroside sphingosine with a sugar residue
(aka glycolipid)
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IV. Glycolipids
Gangliosides sphingosine with multiple sugar
residues Sugars are extracellular A, B and O
blood typing
Multiple sugar units
11
V. Steroids
Tetracyclic ring structure (3 cyclohexane fused
with cyclopentane) Facilitate lipid
digestion Membrane fluidity buffer
How does cholesterol orientate in the membrane?
12
Lipoproteins
Protein attachment to the surface of a membrane
N-Myristoylglycine
13
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?
14
Phospholipids and Glycolipids Self-Assemble to
Form a Lipid Bilayer

• Driving Forces
• H-bonding
• Hydrophobic effect
• Electrostatic interactions
• Van der Waals attractions (close packing)

15
Membrane Fluidity Temperature, Cholesterol and
Fatty-Acid-Composition Regulated
How does membrane composition alter with elevated
temperature?
16
Significant Lateral Albeit Minimal Transverse
Lipid Movement
17
Liposome for Potential Drug Delivery
18
Lipid Bilayer Small-Molecule Permeability
Unassisted membrane crossing linked with H2O and
non-polar solvent solubility Protein
assisted transport





19
Peripheral and Integral Membrane Proteins
Different membrane orientation (a and e),
surface position (f and e) and membrane
componentassociation (d, and g)
What tethers peripheral proteins to the
membrane? What secondary structure is common in
membrane hydrophobic regions?
20
Alpha Helices in the Integral Protein
Bacteriorhodopsin
Bacteria light-harvesting protein that generates
proton gradient a-Helix most common 2
membrane structure Helical (yellow) and charged
(red) residues
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Chapter 8 Problems 1, 3, 5, 7, 9, 19, 21, 23
and 25