Define "polar" and "nonpolar". Which tends to be hydrophobic? Which tends to be hydrophilic? Explain why lipids do not mix well with water.
Polar = Has a separation of charge (dipole moment); nonpolar = Electronegativity difference of 0.5 - 1.9
Polar tends to be hydrophilic
Lipids do not mix well with water because water is polar and lipids are nonpolar. Lipids are hydrophobic
Why are fatty acids named fatty acids? What is "fatty" about them? What is acidic about them?
The acid is a carboxylic acid, the fatty is a nonpolar end consisting of carbon and hydrogen (hydrocarbon) which is lipid soluble (water insoluble).
Eicosapentaenoic acid (shown belos) is the major omega-3 polyunsaturate in fish oils and thus plays a cardioprotective role in nutrition. Using both nomenclature systems introduced in class, describe this fatty acid. You should be able to apply these nomenclature rules to other fatty acids.
Using the omega nomenclature (or n nomenclature): 20:5 omega-3 (20:5 n-3)
Using the delta nomenclature: 20:5 delta - 5,8,11,14,17
What is one reason triacylglycerols make such a good form of energy storage?
Triacylglycerols make a good form of energy storage because they are highly reduced, so they can be oxidated. They also are hydrophobic and thus are not weighed down by water.
What is the importance of the phosphate group in a phospholipid?
The phosphate group is polar and thus is able to interact with the aqueous intercellular and extracellular regions.
What two cell types that we discussed in class have significant glycosphingolipids in their plasma membranes? What other lipid types are cell membranes typically composed of?
Two cell types containing glycosphingolipids: Neural cells and red blood cells.
Lipid types which cell membranes are composed of: glycerophospholipids, sphyngolipids, and cholesterol.
Name four roles of sterols in humans.
Four roles of sterols in humans:
1 - part of the cell membrane
2 - converted to vitamin D
3 - they are hormones (which are transported through the blood stream by proteins)
4 - they are a component of bile salts or bile acids that have a role in digestion.
There are no binding proteins that chaperone eicosanoids through the circulation. How do they accomplish their function despite that?
Their action is meant to be local.
What is the mechanism of aspirin action?
Aspirin blocks cyclooxygenase from converting arachidonate into an eicosanoid, therefore blocking the signaling for pain, fever, inflammation, or clotting.