PROTEINS Proteins Section: The question that involved memorizing content was generally answered well. To obtain full marks for this question, the diagram had to be fully labelled, and an explanation regarding why this situation occurred (rather than just defining the term) was required. There was some confusion regarding the terms amphoteric and zwitterionic, so I would recommend revising these concepts. Some students confused amino acids and nucleotides/transcription, so I would encourage you to make sure that you are aware of the difference between proteins and nucleic acids, and amino acids and nucleotide bases. The second question required applying knowledge using skills gained in the PBLs and the practical classes. Many students understood the techniques and how they could be used. However, many students suggested using precipitation as a technique topurify proteins, if you explained this appropriately then some marks were awarded, however, this is nota technique that you could use to get a lot of your protein if your protein remains in solutionat the end of this process (which is what happened in this example if the technique was used to fractionate). Some students confused cation and anion exchange- I would recommend revising these concepts Many students did not know what an 'elution buffer' was and its purpose, so I would also suggest revising this concept. Remember that you cannot collect your protein fromthe void volume very effectively, so you need to have your protein bind initially and then elute in order to collectit in high amounts. Many students did not use the terms pH, pKa and pI appropriately, so I would recommend revising this terminology. Please remind yourself of what each mean and also remember that proteins don't havea pH the solution around them has a pH. Many students also seemed to forget that they could collect a variety of fractions with ion exchange chromatography and so based on the difference in properties of proteins you can elute them in different fractions using an appropriate elution buffer profile. In regards size exclusion chromatography do not confuse this with a molecular sieve or PAGE, it isa different technique with different requirements. Many students also did not seem to understand that a buffer can't havea property of being positive or negative but could be aqueous or organic. Manystudents also put some form of solid material in as the buffer of a mobile phase. Also remember that porous means the material has pores (holes) in it, water is not porous In general students either knew how to answer this and didn't put in the correct detail (or couldn't separate proteins into different fractions) and therefore didn't get full marks, or they did not understand how to answer thisquestion at all. In this case I would encourage you to go backand listen to the tutorials and lectures as all of these concepts and how you could use them in a sequential fashion were explained in these sessions. But don't forget that the other materialis also examinable and so you should make sure youcan