What should you do in the following situations? Please be as detailed as possibl

Question

What should you do in the following situations? Please be as detailed as possible.

a. You make a 1 M Tris solution that should have come out to pH 7.5, but instead when you measure the pH it is at 5.0.

b. You want to make 250 ml of a 0.5 M solution of Tris (pH 8.0). You weigh out the amount of Tris base that you need (as per the table of amounts of Tris HCl and Tris base used in the class) and then discover that someone has used all the Tris HCl.

c. You want to make 500 ml of a 1 M Tris solution, but miscalculate and weigh out enough Tris HCl and Tris base to make 1.0 liter of the 1M Tris solution.

d. You run a gel to isolate a DNA band, but find that you have used standard agarose, rather than molecular biology grade low-gelling/low-melting temperature agarose.

e. You go to digest your DNA sample with EcoRI, but all you find is the enzyme, but no EcoRI buffer solution is in the freezer.

Explanation / Answer

If Tris solution has lower pH than 7.5, we will add 1M NaOH solution at some extent to meet the pH 7.5. After maintaining, the pH if NaOH solution has been added more than 5% of the total Tris solution then we should need to add extra Tris chemical to maintain the required concentration of Tris solution. For this we can use 0.5 M HCl solution instead of Tris HCl. Both HCl forms require to make the needed the pH of the buffer. Here we need to prepare the 1 liter of 1M Tris buffer and then take out 500 ml for working. This will gives results but can make some false positives. To overcome this situation, do not make the temperature of gel to increase. For this we can use Bovine Serum albumin added universal buffers.

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.