Question

Biochemistry Work

Please answer all parts of each questioni

1) Explain what you would do to make a 10.0 mL of a 10 μM solution of caffeine in water, starting directly from caffeine powder. The molecular weight of caffeine is 456 g/mol. Be detailed in the order in which you would add chemicals and their amounts. Is there something wrong with this? Without being very wasteful, by what other means might you make up this solution? (2 points)

2) You are given the following: water, 10 mM phosphate buffer pH 7.4, EDTA solid (FW 292.25 g/mol), 0.5 M Tris HCl, 3 M NaCl, OAA solid (FW 131.10), NADH solid (FW 709.40), and solutions of NaOH and HCl. Calculate and describe how you would prepare of each of the following: (1.5 points each) (Note: these are solutions we’ll be using!)

50 mL of 0.5 M EDTA pH 8.0

10 ml solution containing 10 mM Tris-Cl pH 8.0 + 100 mM NaCl

10 mL of 20 mM OAA dissolved in 10 mM phosphate buffer pH 7.4

10 mL of 2 mM NADH dissolved in 10mM phosphate buffer pH 7.4

Answer 1

(1) Answer:

10 μM solution of caffeine = 10 x 10^-6M

Grams=Molarity/ (Volume x Molecular weight)

Grams=10 x 10^-6M/ (0.01L x 456g)=2.19 x 10^-6g = 2.19ug

Weighing 2.19ug would be difficult, hence preparing a higher stock and then diluting the same to obtain the required concentration makes sense.

2.19mg of caffeine is weighed and dissolved in a total of 10 mL of water to get a stock of 10mM Caffeine.

10uL of the above stock is made up to 10000 uL using water to get 10 uM of Caffeine.