Membranes-I

Question 1

What are the two possible arrangement for membrane lipids in a aqueous solution?

Answer 1

micelle or lipid bilayer

Question 2

Why are lipid bilayers the favored structure for most phospholipids and glycolipids in aqueous media?

Answer 2

because the long fatty acid carbon chains are to bulky to fit into the interior of a micelle

Question 3

What is the major diriving force behind lipid bilayer formation?

A.Hydrophobic interaction
B. Van der Waal forces
C. Electrostatic and hydrogen-bonding

Answer 3

A. hydrophobic interactions

Question 4

Where do the Van der Waal forces occur between the polar heads or the hydrocarbon tails? what about hydrogen bonding and electrostatic attraction

Answer 4

between the hydrocarbon tails. The polar head groups do the hydrogen bonding and have the electrostatic attraction

Question 5

What are the 3 consequences of the hydrophobic interactions?

Answer 5

1. lipid bilayers have an inherent tendency to be extensive
2. lipid bilayers will tend to close on themselves so that there are no edges with exposed hydrocarbon chains
3. lipid bilayers are self-sealing to keep it in a thermodynamically stable condition

Question 6

If you were going to build a membrane spanning protein what structure motif would you use primarily?

A. Beta sheets
B. Alpha helices
C. Both
D. neither

Answer 6

B. alpha helices

Question 7

What does it mean when you say that the membrane lipids are amphipathic?

Answer 7

means they have both a hydrophobic region and and hydrophilic region