Which of the Following is CORRECT When Considering the Tertiary

Question

Which of the following is CORRECT when considering the tertiary structure of globular proteins?
A) β sheets are usually twisted or wrapped into barrel structures.
B) Hydrophobic residues are normally on the inside and hydrophilic residues are on the outside.
C) The amino acid proline never occurs in a region where the polypeptide chain bends or turns.
D) All parts of the proteins can be classified as helix, β sheet or turns.
E) None of the above.

Accepted Answer

In the tertiary structure of globular proteins, hydrophobic residues are usually buried in the interior (core) of the protein, away from water, while hydrophilic residues are exposed on the surface, interacting with water. This is because water is a polar molecule and is attracted to other polar molecules, such as those found on the surface of a protein. Beta sheets can be twisted, but they are not usually wrapped into barrel structures. Proline is often found in regions where the polypeptide chain bends or turns, due to the rigid conformation of its side chain. All parts of proteins cannot be classified as helix, β sheet, or turns as there are many other structural elements present in proteins, such as loops and coils.