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Unformatted text preview: Professor Hinck Bio 110, problem set 2 1) Draw in detail a basic phospholipids and describe how phospholipids arrange themselves in the lipid bilayer. Think about a lipid and about what would happen to the bi-layer if parts of the lipid were modified i.e. if the hydrocarbon chain was longer than normal etc. etc. ANS) see Fig 10-3 and then ask yourself about some changes and how it would affect things. So for example, what happens to membrane fluidity if all the hydrocarbons are really short (more fluid) or really long (less fluid) or completely saturated (less) etc etc. 2) Five students in the class always sit together in the front row. This could be because A) they really like each other or B) nobody else in the class wants to sit next to them. Which explanation holds for the assembly of a lipid bilayer? Explain? If the lipid bilayer assembled for the opposite reason, how would its properties differ? ANS) Lipid bilayers assemble because the surrounding water molecules exclude the component lipids; thus, analogy (2) is the correct one. If bilayers formed because of attractive forces among the lipids—analogy (1)—the properties of the bilayer would likely be quite different. Molecules ‘attract’ one another by forming specific bonds that hold them together. Such bonding among lipids would make the bilayer less fluid, perhaps even rigid, depending on the strength of the interaction. 3) Predict which of the following organisms will have the highest percentage of unsaturated fatty acid chains in their membranes. A) Antartic fish B) Desert Iguana C) Human being D) Polar bear E) Thermophilic bacterium ANS) A. Antarctic fish, which are cold-blooded, live in freezing waters. In order to maintain an appropriate fluidity of their membranes under such extreme conditions, they require a higher proportion of unsaturated fatty acid chains Professor Hinck Bio 110, problem set 2 in their membranes. Polar bears also live in extreme cold, but they are warm-blooded and maintain a high internal temperature; thus, they have no special requirement for unsaturated fatty acids in their membranes....
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This note was uploaded on 11/07/2009 for the course BIOCHEM bIO taught by Professor Professor during the Spring '09 term at École Normale Supérieure.
- Spring '09