Question

multiple choice question
an alpha helix is an example of ______ structure of a protein.
o primary
o secondary
o tertiary
o quaternary

Explanation:

Protein structure has four levels. The primary structure is the linear sequence of amino - acids. The secondary structure refers to local, regular folding patterns like alpha - helix and beta - sheet, which are stabilized by hydrogen bonds. Tertiary structure is the overall 3 - D shape of a single polypeptide chain. Quaternary structure is the arrangement of multiple polypeptide chains in a multi - subunit protein. Since alpha - helix is a local regular folding pattern, it is a secondary structure.

Answer:

B. secondary