Match the following choices to questions 1–4:

a. innate resistance

b. naturally acquired active immunity

c. naturally acquired passive immunity

d. artificially acquired active immunity

e. artificially acquired passive immunity

The type of protection provided by the injection of diphtheria toxoid.

Video transcript

Hi everybody. And welcome back. The next problem says all of the following processes allow humans to produce a diverse pool of antibodies. Despite the limited number of genes except a somatic recombination. B, combinatorial diversity. C somatic hyper mutation or D colonial expansion. So we're thinking about the fact that despite our relatively limited number of genes, we can produce millions and millions of possible different types of antibodies. So what are the processes that allow this to take place? Or in this case, our questions saying which one of these processes is not one of the factors most diversity? Well, even if we can't remember off the top of our head, which it is we have a clue in the very words themselves. So when we look at our answer choices here, choice, a somatic recombination, when we think recombination, we think things combining in different ways. Choice B, combinatorial diversity. That sounds like difference. Choice C somatic hyper mutation, obviously mutation, we think of DNA changes. But when we get to choice D, we have clonal expansion. So the word clonal makes us think clones identical DNA. So this is an example of how just looking over our choices, looking at the words themselves can help us in a multiple choice question, even if we don't recall the information right away. And choice D clonal expansion is indeed our answer. It's obviously a really, really important part of our immune response. Because when we get the specific antibody that binds the best to our antigen, we want to make lots and lots of copies of it. So the process of clonal expansion is the process of the proliferation of the B cells that have the best binding to a particular antigen. So it's the amplification of a specific response to a pathogen that the body has recognized. So when we look at our other answer, choices, let's think about what each of these things are. Well, somatic recombination comes early in the process. This is during B cell development and is the recombination of the gene segments that encode the variable regions of the various immunoglobulins. This leads to a diverse selection of B cells each with their own unique antibodies. So again, this is the sort of this beginning of the process just churning out all these different variations um by recombination of those gene segments. So it's not our answer because obviously this is the sort of the beginning of this process of producing a diverse pool of antibodies. And then choice C somatic hyper mutation comes later. So this is after we have activation of the B cells. So we've produced all these different antibodies, B cells have been activated, we have something that's a good response, a good match. But now we want to optimize that. So then when we have that, uh when we have that antibody that binds really well, then again the variable region undergoes hyper mutation loss of mutations occurring there producing slightly different versions of this antibody. And the one that fits best is selected for in future generations to undergo colonial expansion. So that variable region genes there undergo random mutation leading to a new generation of antibodies with increased affinity for the specific antigen the body is dealing with at that time. So that's why choice C also is not our answer. Since again, part of that process of producing a diverse pool of antibodies. And then choice B combinatorial diversity is not a process but just a term that describes the vast number of unique antibodies possible through these processes like somatic recombination and somatic hyper mutation. So again, that's part of the whole overall processes that produce diverse pools of antibodies. But again, our answer here for the one that does not describe part of this process is colonial expansion, which is the proliferation of the cells. So they've already undergone somatic recombination, they've already undergone somatic hy permutation. Now we have our best antigen, the optimized one and we want to make lots and lots of it to respond to a pathogen. So choice, the clonal expansion is our answer here. See you in the next video.