This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
[{'content': 'Which part is responsible for the class of immunoglobulin? \nSelect and explain. \nA. Heavy chain, B. Light chain, C. Both, D. None', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e. Heavy chain * There are five immunoglobulin classes (isotypes) of antibody molecules found in serum: IgG, IgM, IgA, IgE and IgD. They are distinguished by the type of heavy chain they contain.* IgG molecules possess heavy chains known as g-chains; IgMs have m-chains; IgAs have a-chains; IgEs have e-chains; and IgDs have d-chains. The variation in heavy chain polypeptides allows each immunoglobulin class to function in a different type of immune response or during a different stage of the body's defense.", 'role': 'assistant'}]