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Preparation of 5X TBE Electrophoresis Buffer
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TBE is a very common electrophoresis buffer for DNA agarose gel electrophoresis. It is prepared as a 5X stock solution that can be diluted to 1x or 0.5x working solution for DNA agarose gel electrophoresis. The 5X concentrated solution contains 0.445 M Tris borate and 0.01 M EDTA (pH 8.2 – 8.4).
A 5X stock solution is prepared by dissolving 54 g Tris base, 27.5 g Boric acid, and 20 ml of 0.5 M EDTA in water to a final volume of 1000 ml. The solution is sterilized by autoclaving and is stored at room temperature.
Preparation of LB Lennox Broth
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LB medium is a rich growth medium, commonly used to grow E. coli. LB, Lennox Broth contains 1% Bacto-tryptone, 0.5% Bacto-yeast extract and 0.5% Sodium chloride. A 1000 ml LB, Lennox Broth is prepared by dissolving 10 g Bacto-tryptone, 5 g Bacto-yeast extract and 5 g sodium chloride in deionized water to a final volume of 1000 ml. After adjusting the pH 7.0 with 5N NaOH medium is autoclaved and stored in a cold room.
Stock Solution
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A stock solution can be defined as a highly concentrated solution, mostly prepared as a 10x concentrated solution, which can be diluted to prepare a working solution. Stock solutions can also be used as a component to prepare complex solutions containing many ingredients. For example, a stock solution of EDTA (0.5 M EDTA solution) can be used to prepare many solutions which contain EDTA e.g., TAE, TBE, Tris-EDTA, Trypsin-EDTA etc.

