Question

How would I do calculations to get the final glucose concentration after the falcon tubes were made? The procedure is:

1. Mastermix culture was made by adding (1) 1 mL of E. coli with pGLO culture, and (2) 25 uL of 100mg/ml carbenicillin, into 24 mL of LB media (lysogeny broth, Miller’s modification)
2. Step 1 was repeated twice to generate three total Mastermix cultures labeled #1, 2, 3, respectively
3. 4 aliquots were prepared by adding 4.5 mL of Mastermix #1 into four, separate, 14 mL falcon tubes, labeled control #1, arabinose #1, glucose #1, catabolite #1
4. Different components were added to each labeled falcon tube appropriately
4a. Control #1: 500 ul water
4b. Arabinose #1: 250 ul of 20% arabinose + 250 ul water
4c. Glucose #1: 250 ul of 20% glucose + 250 ul water
4d. Catabolite #1: 250 ul of 20% arabinose + 250 ul of 20% glucose

Answer 1

4c. Glucose #1: 250 ul of 20% glucose + 250 ul water

20% of glucose = 20g of glucose / 100ml of water

So, for 1ml = 0.2g of glucose needed.

So, for 250ul or 0.25ml = 0.2g/4 = 0.05g = 50mg

The 50mg of glucose added in 250ul of water.

4b. Same as Arabinose 50mg of arabinose in 250ul of water.