Category: Reagents

Magnesium Chloride (MgCl2) is soluble in water. Magnesium chloride is available in anhydrous as well as hydrated forms. Since anhydrous Magnesium chloride is hygroscopic (quickly absorbs water from the air), it is convenient to use hydrated forms that are easy to weigh out the right amount accurately. For this reason, Magnesium chloride hexahydrate (MgCl2.​6H2O, Molecular Weight: 203.30) is often used to prepare a 1 M Magnesium chloride solution. A 1M stock solution can be prepared by dissolving 203.3 g of MgCl2.​6H2O (Molecular Weight: 203.30) in water to a final volume of 100 ml. In the following section, we describe a procedure to prepare 100 ml of 1M MgCl2 stock solution.

SOB (Super Optimal Broth) medium is a nutrient-rich microbial growth medium, designed by Douglas Hanahan in 1983. SOB or its glucose-supplemented version SOC is often used during transformation of E. coli competent cells with plasmids (added in transformed cells after heat shock). It results in better survival and higher transformation efficiency as compared to regular LB medium. It contains 2% Bacto-tryptone, 0.5% Bacto-yeast extract, 0.05% Sodium chloride, 2.5 mM KCl, and 10 mM MgCl2. A 1000 ml SOB medium is prepared by dissolving 20 g bacto-tryptone, 5 g bacto-yeast extract, 0.5 g sodium chloride and 2.5 ml of 1M KCl in water to a final volume of 1000 ml. Medium is sterilized by autoclaving. MgCl2 (5 ml of 2M MgCl2) is added just before use.

A 100 ml of 4% (w/v) paraformaldehyde can be prepared by dissolving 4g of paraformaldehyde in PBS to a final volume of 100 ml.

Here we have described a procedure to prepare 10 M (or 10 N) sodium hydroxide (NaOH) solution. A 10 M NaOH solution can be prepared by dissolving 40 g of NaOH (Molecular Weight: 40.00) in water to a final volume of 100 ml. Since dissolution of NaOH in water is a highly exothermic reaction, extreme care must be taken while preparing the solution.

Molarity of Tris solution: M (Change the molarity of the solution)   Volume of stock solution: ml (Change the volume…

A 50x TAE buffer can be prepared by mixing and dissolving 242 g Tris base, 100 ml of 0.5 M EDTA and 57.1 ml glacial acetic acid in a deionized water to a final volume of 1000 ml. The pH of the final solution should be between 8.2 – 8.4. 

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.

Step 1: To prepare 10 ml of stock solution of kanamycin, weigh out 500 mg of kanamycin. Transfer it to…