Antibody Diversity

Why are so many kinds of antibodies necessary? The immune system acquires immunity to specific antigens over time. It is important to realize that the acquired immunity does not come about through the creation of new types of immune system cells and their associated antibodies after infection. Thousands of types of immune cells exist in the body. Many of them have antibodies for antigens that have never been found in our species or may not exist at all. Once an antigen is detected then the body begins to produce many more copies of the appropriate cell and antigen. Immunity is acquired by making more copies of pre-existing cells not by creating something new. Therefore a huge number of cells are necessary to combat the wide range of potential antigens.

View the animation below, then complete the quiz to test your knowledge of the concept.


1	Light chains are made of

		A)	one V and one J segment in the variable region plus a constant region that is common in all light chains
		B)	one V, one D, and one J segment in the variable region plus a constant region that is common in all light chains
		C)	one V and one J segment in the variable region plus one of two possible different constant region segments
		D)	one V and one J in the variable region and no constant region

2	Heavy chains

		A)	all have the same constant region
		B)	have one of two possible constant regions
		C)	have one of five possible constant regions
		D)	have one of eight possible constant regions

3	The V, J, and D segments

		A)	must be a matching set
		B)	are each selected randomly
		C)	are present in the constant region of the heavy chain
		D)	are RNA sequences

4	Human cells have separate genes for each antibody molecule.

		A)	True
		B)	False

5	The m gene codes for the constant region of the light chain in IgM antibody.

		A)	True
		B)	False

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