20.109(S13): TA notes for module 2

S13 notes: This experiment will be largely unchanged from the S12 version, with three potential exceptions: (1) The 8th day will be added back, dedicated solely to in-class analysis; (2) More than three reference mutation options will be offered, after additional pilot experiments are run; (3) Possibly the final assay will be done in Tris or similar buffer rather than water, IFF the wild-type and other reference cases are reproducible in this format. I also would like to re-frame some of the lecture and lab content to emphasize signal measurement theory.