Question

Alpha-helix is found in which level of protein structure ?

• A. Tertiary structure
• B. Quaternary structure
• C. Secondary structure
• D. Primary structure

Hint:

Think of protein levels like a phone cord: The wire is Primary, the coiling of the wire is Secondary, the tangled mess of the cord is Tertiary, and multiple cords together is Quaternary.

Answer 1

The Correct Option is C

Protein structure is organized into four hierarchical levels:
• Primary Structure: The linear sequence of amino acids in a polypeptide chain.
• Secondary Structure: Refers to local folded structures that form within a polypeptide due to hydrogen bonding between the backbone atoms. The Alpha-helix and Beta-pleated sheets are the two most common types of secondary structure.
• Tertiary Structure: The overall three-dimensional shape of a single polypeptide chain, formed by folding the secondary structures.
• Quaternary Structure: The arrangement of multiple folded protein subunits in a multi-subunit complex (e.g., Haemoglobin).