This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
An Immunoglobulin molecule represents the following level of organized protein structure 
Select and explain. 
A. Primary structure, B. Secondary structure, C. Tertiary structure, D. Quartenary structure
D: Quartenary structure
Answer: D: Quartenary structure 
Explanation: A complete immunoglobulin molecule represents Ouanternary level of organization between four polypeptide chains (two light chains and two heavy chains). It has a heterotetrameric quaternary structure.