1. Disc-shaped phospholipid particles, called bicelles, can be used to mimic mem
ID: 202718 • Letter: 1
Question
1. Disc-shaped phospholipid particles, called bicelles, can be used to mimic membrane bilayers in order to study protein-membrane interactions in vitro. Bicelles are flattened micelles that look like a pancake (-40 A thick;lipid bilayer is 36 Athick. bicelle 40 A a) If each methylene (-CH2-) group in a straight-chain hydrocarbon advances the chain length by about is this? (Note, you should consider the terminal carboxylic acid C as a methylene group.) (5 pts) 0.13 nm, what length fatty acid would most likely be found in each half of the bicelle? What fatty acid b) Would you come to the same conclusion for a typical plasma membrane? If not, which length fatty acidls) would you likely find in a typical cellular membrane? Show calculations and explain. (3 pts)Explanation / Answer
a.
Thickness of bicells = 40 A = 4 nm
Lentgth of -CH2- group = 0.13 nm
Number of carbon atoms possible = 4/0.13 = 30.769
Bicelle contains two fatty acid chains along its width.
So, number of C-atoms in single fatty acid = 15 or 16
C15:0 = Pentadecanoic acid = CH3(CH2)13COOH
C16:0 = Hexadecanoic acid = Palmitic acid = CH3(CH2)14COOH
b.
Thickness of lipid bilayer = 36 A = 3.6 nm
Lentgth of -CH2- group = 0.13 nm
Number of carbon atoms possible = 3.6/0.13 = 27.69
Lipid bilayer contains two fatty acid chains along its width.
So, number of C-atoms in single fatty acid = 14 or 13
C14:0 = Myristic acid = Tetradecanoic acid = CH3(CH2)12COOH
C13:0 = Tridecylic acid = Tridecanoic acid = CH3(CH2)11COOH
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