I listed some methods by which the human immune system generates a diversity of antigen receptors. The specific example I used was the heavy and light chains of B lymphocyte immunoglobulin. However, I did not attempt to relate the methods of generation to their cellular mechanisms.
Lymphocytes recognise pathogens with antigen receptors.
The receptors contain 'heavy' and 'light' protein chains, assembled from three and two gene segments respectively. Genetic diversity - large numbers of V,D and J genes per organism 3. Junctional - imprecise joining of segments 5. Although an individual organism can only have two alleles at each locus, a sexually reproducing population has the potential to maintain more alleles. This is because the two alleles in one organism do not have to be the same as the two alleles in another organism.