Suppose you spend years biochemically purifying an integral membrane protein from a highly pathogenic, brain infecting species of amoeba (a eukaryote). You perform Edman degradation on the purified protein and determine its N-terminal six amino acids are: CERSEI. You decide to use this sequence to construct single-stranded, radioactive DNA probes that you can use to screen a huge cDNA library generated from this amoeba, in hopes of isolating the cDNA that encodes the protein.
How many different DNA probe molecules do you need to synthesize? (show your math)

Let’s say you find a plasmid in the amoeba library that is bound tightly by one of your radioactive probes. Does the region of this cDNA bound by the probe represent an exon, an intron, a regulatory region near the gene, or none of the above? (circle the correct answer)

You decide to name this ameoba protein Joffrey, and you determine that it has a single region of consecutive nonpolar amino acids (positioned ~100 amino acids past the CERSEI sequence) that meets the criteria for a membrane-spanning region. All other regions of Joffrey have no more than two consecutive nonpolar amino acids. Your hated arch-rival, employed at a nearby university, hypothesizes that this lone transmembrane region in Joffrey is a +/- start-transfer sequence. In a concise yet scathing letter, you reject his hypothesis and put forth a revised one. Show me your letter, and be sure to explain how your hypothesis is supported by evidence on this exam page.