I was reviewing lecture nine and came across something I did not fully understand. Regarding alternative splicing and handout 9B: 1) is there any reason for one polyA site to be utilized over another?

In terms of cell and organismic function, yes. If one polyA site is used, the cell has a membrane bound antibody which can detect the presence of antigen; if the other polyA site is used, the cell produces large amounts of soluble (secreted) antibody which can be used to inactivate the antigen. The presence of antigen is what switches the system from the first state to the second.

This response to antigen is "useful" to the organism overall -- it allows a multicellular organism to produce the "right" antibody to destroy a specific infectious agent, but only when that agent comes along. The organism doesn't intentionally or consciously switch gears -- this is a mechanistic response which has evolved over millions of years. The organisms that responded in this way survived infection, flourished and left many descendants who could mount the same immune response; those that didn't respond in this way (by making antibody in response to antigen) didn't reproduce as well and died out.

2) ... more.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.