8. Consider a short polar charged region and a short non-polar region in a long polypeptide chain. When dissolved in water, the polypeptide will most likely fold to form a protein in which:

Question

A. The non-polar region is exposed on it surface and the polar region is interior.
B. The polar region is exposed on its surface and the non-polar region is interior.
C. Both the non-polar and polar regions are exposed on its surface
D. Both the non-polar and polar are interior

Answer 1

In an aqueous (water) environment, polar (hydrophilic) regions of a protein tend to be on the surface where they can interact with water, while non-polar (hydrophobic) regions tend to be buried in the interior of the protein to avoid contact with water. Therefore, when a polypeptide folds in water, the most likely arrangement would be:

B. The polar region is exposed on its surface and the non-polar region is interior.

This arrangement minimizes the free energy of the system by maximizing interactions with water for the polar regions and minimizing exposure to water for the non-polar regions.