Other Sources of Diversity

The random combination of V and J segments alone can produce millions of possible combinations. More diversity arises because the joining of V and J chains is done imprecisely, with the possible loss or gain of several nucleotides, resulting in added or deleted amino acids.

Remember also that each antibody includes both light and heavy chains. Heavy chains are produced by a similar combinatorial process, using a different, larger set of gene segments. The combination of a randomly produced light chain with a randomly produced heavy chain produces even more diversity. Finally, when a B cell multiplies in response to antigens, the

infected cell

The T cell identifies an infected cell by binding to an antigen held within an MHC molecule on the surface.

rearranged gene can mutate, making some members of the clone different from others. The number of possible antibodies available through all these processes is in the trillions.

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