Describe the structure of an antibody and explain the roles of its variable and constant regions.
An antibody is a Y-shaped protein composed of four polypeptide chains: two identical light chains and two identical heavy chains, linked by disulfide bonds. Each chain has a variable (V) region at the tips of the Y, which binds specifically to antigens at their epitopes, and a constant (C) region, which forms the stem and is recognized by immune cells. The variable region determines antigen specificity, while the constant region mediates interactions with other components of the immune system.
What is the difference between monoclonal and polyclonal antibodies, and how are they produced?
Monoclonal antibodies are identical antibodies produced by a single B cell clone and bind to the same epitope on an antigen. Polyclonal antibodies are a mixture produced by different B cells and recognize multiple epitopes on the same antigen. Monoclonal antibodies are generated by culturing a single B cell clone, while polyclonal antibodies are produced by immunizing an animal and collecting the diverse antibodies generated by its B cells.
What are the two main types of immunity and which one involves antibodies?
The two main types of immunity are innate (nonspecific) and adaptive (specific) immunity. Antibodies are involved in adaptive immunity, specifically in the humoral branch.
Describe the basic structure of an antibody.
An antibody is a Y-shaped protein made of four polypeptide chains: two identical light chains and two identical heavy chains, linked by disulfide bonds.
What is the function of the variable (V) region of an antibody?
The variable region is located at the tips of the Y and binds specifically to antigens at their epitopes, determining the antibody's antigen specificity.
What role does the constant (C) region of an antibody play?
The constant region forms the stem of the Y and is recognized by immune cells, mediating interactions with other components of the immune system.
List the five classes of antibodies and state what distinguishes them from each other.
The five classes are IgG, IgA, IgM, IgE, and IgD, and they are distinguished by differences in their heavy chains.
How does antibody diversity arise in the immune system?
Antibody diversity arises from gene rearrangements, splicing, and mutations, allowing the production of a vast array of different antibodies.
What is the difference between monoclonal and polyclonal antibodies?
Monoclonal antibodies are identical and bind to the same epitope, produced by a single B cell clone, while polyclonal antibodies are a mixture from different B cells and recognize multiple epitopes on the same antigen.
Name two main functions of antibodies in the immune response.
Antibodies neutralize toxins and tag pathogens for destruction by immune cells such as phagocytes.