Field of Science

Waiting for the colonies to grow

OK, I did my assigned E. coli transformation experiment, though it took a couple of days.  I did find out that cells with the sxy plasmid grow just as well as those with the no-insert plasmid, at least in the absence of the inducer IPTG.  I still need to have someone show me how to use the nano-drop DNA-concentration spec, and before using it I need to further clean up my DNA prep to get rid of the RNA.  (I know there's RNA in it because I estimated its concentration and quality (fragment length) by running it in a gel.)

When I was in grad school we always added tetrazolium tetrachloride to our minimal plates because it makes the colonies red and easy to see.  I couldn't find any instructions for using it in minimal plates but I found old (Lederberg-old) instructions for using it in nutrient agar, so I used that concentration.

Now I just need to wait for the colonies to grow.  That will be slow because they're on minimal agar, so they probably won't be countable until tomorrow.  I can spend the intervening time helping grade my last exam question and entering the numbers into my spreadsheet, and then doing the Excel-wrangling to get the final grades for my ~400 freshman biology students.

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