My professor told us that there are about a million different B cells based on their surface receptor.
I have read that we have about 30000 genes in all. Since receptors are proteins how do these 30000 genes make such a large number of receptors? I read about something called alternative splicing. Is this the mechanism behind this?
Alternate spicing of mRNA is a real phenomenon, but it's not the source of immune cell receptor diversity. The DNA of immune cells is rearranged in a slightly random manner, to make a receptor with a random sequence in the variable portion of the receptor. As Armatus already said, the process is VDJ recombination. Here is a link to a textbook on NCBI
Yes - in short, splicing enables one gene to be 'read' in multiple different ways. Imagine you have a set of letters; you can make one long word out of them, or cut some words out to make a shorter, different word. The same logic applies to gene expression, in that one gene could be made to code for a variety of different proteins (in this example, surface receptors).
