Biochemistry postgraduate personal statement example

Personal statement example

The first gel from my final-year project had two bands where I expected one. I had expressed a His-tagged lactate dehydrogenase in E. coli and purified it on a nickel column, and alongside the band at roughly the right size sat a fainter one just below it. My supervisor suggested I work out what it was before worrying about it. Over the next fortnight I adjusted the imidazole concentration in my wash buffer, ran fractions side by side and compared freshly lysed samples with ones left on ice. The lower band grew in the older samples, which pointed towards proteolysis rather than a contaminating host protein, and adding protease inhibitor during lysis reduced it considerably. It was a modest result, but it taught me to read a gel as evidence rather than as a picture, and it is the kind of reasoning I want to develop further through postgraduate study in biochemistry.

The main aim of the project was kinetic. Using a spectrophotometer, I followed the oxidation of NADH at 340 nm as the enzyme converted pyruvate to lactate, and I fitted initial rates to the Michaelis-Menten equation to estimate Km for pyruvate. My early replicates were inconsistent until I realised I was not measuring rates over a consistently linear period. Once I standardised the window and prepared substrate dilutions fresh each session, the scatter narrowed. I also saw signs of reduced activity at the highest pyruvate concentrations, which fits the substrate inhibition reported for some lactate dehydrogenase isoforms. I did not have time to test this properly, and I noted it in my report as an open question rather than a finding. Writing up the project made me realise how much I enjoyed connecting a protein's structure to numbers I could measure on a bench.

My degree gave me a broad base in genetics, cell biology and microbiology, but the modules I returned to most were those on protein structure and metabolism. I chose an optional course in bioinformatics and used it to compare lactate dehydrogenase sequences across several organisms, looking at conserved residues near the active site. Seeing that the arginine involved in substrate binding was preserved across distant species made the structural diagrams from lectures feel much more concrete. Outside the syllabus I have read Nick Lane's The Vital Question, which made me think about energy metabolism as a problem with a history rather than a fixed set of pathways. I would like postgraduate study to give me firmer grounding in structural methods and a chance to design experiments with more independence than an undergraduate project allows.

Since my second year I have worked weekends at a garden centre, mostly on the tills and in the plant area. It is unrelated to biochemistry, but it has made me reliable and calm with the public on busy bank holidays, and I am now trusted to open up and to train new seasonal staff on the stock system. I also sing tenor in a community choir. Learning a part at home and then fitting it alongside thirty other people each week has made me comfortable working on something where my contribution matters but only makes sense alongside everyone else's, which is not far from how a shared lab operates.

I am applying for a Masters because I want to move from following protocols competently to understanding why they work and when they fail. I am particularly interested in enzyme mechanism and in how protein stability affects what we can measure in vitro, and I would welcome training in techniques such as structural analysis and biophysical characterisation that I have so far only read about. I bring careful practical habits, a willingness to stay with an awkward result until I understand it, and the steadiness that comes from balancing study with regular work. I would like to use a postgraduate year to test whether research is the career I want, and I expect to approach it with the same patience I gave that second band on my first gel.