Question

4) Length of a Fatty Acid: The carbon-carbon bond distance for single-bonded carbons such as those in a saturated fatty acyl chain is about 1.5 A (angstrom = 10-10 m = 0.1 ?m).

a) Estimate the length of a single molecule of palmitate in its fully extended form. If two molecules of palmitate were placed end to end, how would their total length compare with the thickness of the lipid bilayer in a biological membrane? (The thickness of a lipid bilayer is 50 to 80 A)

b) Would it matter if the acyl chain contains one or two trans unsaturated bonds as in trans - $\Delta$ ⁹ octadecenoate or trans, trans - $\Delta$ ^9,12 octadecadienoate? Why or why not? Would it matter if the unsaturated bonds were in the cis conformation? Why or why not?

Answer 1

a) The length of a single molecule of palmitate in its fully extended form is 19.6652 A⁰.

If two molecules of palmitate were placed end to end, their total length is 39.3305 A⁰ which is less compare to that of the thickness of the lipid bilayer in a biological membrane.

The 3D image is shown below.