Assignment: For each question, describe how you would make the solution using th

Question

Assignment: For each question, describe how you would make the solution using the stocks or reagents listed below.

On our lab prep shelves, we have the following solutions and powders:

Sodium citrate (FW = 43.7 g/mol)

SDS powder (FW = 288.38 g/mol)

0.5 M EDTA

IPTG powder (FW = 238.3 g/mol)

20 mg/mL X-gal solution

1000X ONPG

Premade LB

Premade LB agar

0.5 mM Colchicine

50X gel running buffer

Agarose powder

95% ethanol

100 mg/mL Ampicillin

10X BamHI restriction enzyme digestion buffer

milliQ water

dimethylformamide (DMF)

Example 1. (DNA isolation lab) How would you make 100mL of 0.15M Sodium Citrate, 5% SDS, 0.001M EDTA solution (one solution that contains all of these reagents)?

Answers

0.65 g Sodium citrate

5 g SDS

0.2 mL of 0.5 M EDTA

Add 75 ml of water and mix well. Then add water up to 100 ml to complete.

Example 2. (B-gal) How would you make a 10 fold dilution of 20 mg/ml X-gal? X-gal is not soluble or stable in water, but it is in dimethylformamide. What would the concentration of the diluted solution be?

Answer

Add 1 ml of the stock solution to 9 ml of DMF. 2 mg/ml

Problems for you:

1. (B-gal) How would you make 10 mL of a 0.1 M IPTG solution?

2. (hemoglobin) How would you make 250 mL 1X running buffer for your gel?

3. (B-gal) How would you make 48 ml of a 1X ONPG solution?

4. (B-gal) How wou50*ld you make 150 ml of a 100 mg/ml X-gal solution?

5. (restriction enzyme digestion). You are planning to do a 45 ml restriction digestion with BamHI. How much 10 X restriction enzyme buffer do you need to include?

6. (hemoglobin) How would you make 150 mL of 1.5% agarose (w/v) in 1X running buffer?

7. (hemoglobin) How would you make 7.5 L of 70% ethanol?

8. (transformation) How would you make 100mL LB agar + 100mg/mL Ampicillin?

9. (transformation) If we need 5.5 L of LB + 100 mg/mL Ampicillin for all three lab sections, how much total antibiotic do we need to order? Answer in mg.

10. (B-gal) How would you make a 4 fold dilution of X-gal? What would the concentration of the diluted solution be?

11. (DNA isolation) You need to read the absorbance of your DNA, but the DNA is too concentrated to get a good reading. You need to make a 10 fold dilution, but you do not want to dilute your whole sample. How would you make a 1 mL sample of your DNA to analyze?    

12. How would you make 2 ml of a 2 fold dilution of colchicine?   What would the concentration of the diluted solution be?

13. (B-gal) How would you make 500 mL LB + 40 mg/mL X-gal? (the LB is made, so you just need to figure out how much X-Gal to add)

14. (B-gal) How would you make 500 mL LB + 0.1 mM IPTG?

15. (B-gal) How would you make 500 mL LB + 40 mg/mL X-gal + 0.1 mM IPTG?

16. (B-gal) You need to make more of the 20 mg/ml X-gal stock, but somebody put an almost empty jar back on the shelf there is only 11 mg of X-gal left. How much water would you add to use the rest of the powder up before buying more?

17. (DNA isolation) Holy cow, last years TAs were lazy. You want to make a large quantity of 0.2 M sodium citrate, but there is only 0.5 g on the shelf. How much could you make?

18. (B-gal) For ONPG, we use a 1000X stock - what is the concentration of the 1000X stock if the working (1X) concentration is 0.013 M?

19. (B-gal) How would you make 4 mL of 0.013 M o-nitrophenol-b-D-galactoside (ONPG)?

20. (DNA isolation) How would you make 100mL of 0. 1M EDTA solution?

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Explanation / Answer

Q1. 1. (B-gal) How would you make 10 mL of a 0.1 M IPTG solution?

Answer: We have IPTG powder (FW = 238.3 g/mol)

Molarity = moles/ volume in liters

moles = mass taken/molar mass

So, given molarity = 0.1M and volume = 10ml =0.01L

So, moles = molarity x volume = 0.1 M x 0.01L = 0.001moles

0.001moles = mass / 238.3g/mol

mass to be taken = 0.2383g

SO, preparation : Weigh 0.2383 grams of IPTG powder in a 10mL volumetric flask and fill it with water to the mark to get 0.1M 10mL IPTG solution.

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