Final answer:
The five classes of immunoglobulins, distinguished by their heavy chains, are IgM, IgG, IgA, IgD, and IgE. The structure of these chains determines their role in immune responses, with IgG being the most abundant and containing three constant domains, while IgM and IgE have four, and IgA and IgD have three.
Step-by-step explanation:
The five classes of immunoglobulins (heavy chain) are IgM, IgG, IgA, IgD, and IgE. These classes are differentiated by the structure of their heavy chains, which determine the immunological functions and characteristics of each antibody class. For example:
- IgG antibodies are the most abundant and have heavy chains consisting of one variable domain (VH) and three constant domains (CH1, CH2, CH3).
- IgM and IgE each have four constant domains on their heavy chains.
- IgA and IgD have three constant domains per heavy chain.
The heavy chains are designated by Greek letters: gamma (γ) for IgG, mu (μ) for IgM, alpha (α) for IgA, delta (δ) for IgD, and epsilon (ɛ) for IgE. Each class plays a unique role in the immune system, with antibodies of the same binding specificity able to be present in different classes and thus contributing to various immune functions.