I had what was probably the worst practical of the semester yesterday, through no fault of mine.

Yesterday, we had to extract plasmid DNA from the bacterial cells we plated on Tuesday, with which we were on time, well to be exact, we were AHEAD of time until my TA interferred.

There was a step with required us to measure the concentration of DNA extracted(nanodrop), and there were only 3 such machines in the entire lab catering for all 150 odd students in the lab. Each student had to measure 5 samples, so there were 750 samples in total, approximately 250 samples per machine.

While the nanodrop would more or less serve as a confirmation that we had DNA, it was unnecessary for us to measure the DNA before moving onto the next step which involved digesting the DNA with enzymes over 2 hours.

But no..... my TA said we HAD to measure the DNA before moving onto the digestion. And when we asked if we could prepare our enzyme master mix beforehand, she said no! So off we went, and queued at the freaking machine for 1h40mins! By the time we had our concentrations, it was almost 4pm and the lab manager and TA actually gave us disapproving looks! Other benches had actually performed the digestion and used the 2h waiting time to queue and do the nanodropping.

Needless to say, we were really far behind by then and we still needed to run a gel elecetrophoresis which would take an hour or so. We started our digestions at 4.10pm (because we had to prepare our master mix from scratch when the other TAs prepared it for their students!). We had to disrupt the digestion process at 4.40pm to load half of the reaction volume into the gel for electrophoresis.

(and then here's where I stopped and couldn't be bothered to continue. LOL)