Question

1)You are given a protein solution with a concentration of 0.15 mg/ml. We need 10 µg for an experiment. What volume of the protein solution do we need?

My answer: Convert 0.15 mg/ml to μg/ μl and you will get 150 μg/ μl. C = M/V rearrange for Volume V= M/C , V= (10 μg)/(150 μg/ μl) = 0.06667 μg/ μl

2) Suppose we want to prepare a solution containing 100 µg of the protein at a concentration of 1 mg/ml. To do this we will first dry down enough protein solution to get 100 µg. How much do we need to dry down? How much H2O do we add to the dried protein to get the desired concentration?

My answer: You will convert 0.15 mg/ml to μg/μl and you will get 150 μg/μl, then take 100 μg and divide by 150 μg/ μl to get 0.667 μg/ μl (I don't think I am doing this right) Please help!!

3) If the protein has a M.W. = 22,000, express its initial concentration in moles/liter, in µmoles/ml and in µmoles/µl. If we want 20 µmoles for a reaction, what volume do we need?

4) Suppose we want 1 ml of a 10 µg/ml solution. How much H2O and protein stock must we add to get this?

5) Suppose we want 100 µl of a 0.1 µg/µl solution. How much H2O and protein stock must we add to get this?

I am trying to do these questions but I am horrible at this and I feel like I am doing it wrong. I need help please!!

Answer #1

You are given a solution of 100 mg/ml and are asked to make
solutions of 10 mg/ml, 1 mg/ml, 100 µg/ml, and 10 µg/ml. You will
need 500 µl of each of the above solutions. Describe the most
efficient way to end up with about 1 ml of each of the above
concentrations

You have 5 ml of 3 mg/ml protein soluti on. (This solution is
valuable so you don’t want to waste it.) How w ould you make up at
least 100 μ l of 0.1 mg/ml using a convenient dilution ( i.e . how
much buffer and how much protein solution do you need to add, and
is it possible to pipet the amount you need accurately )? Please
explain and provide the correct answer.

You isolate a subcellular fraction and find the protein
concentration to be 40 mg/mL.
a) Show all calculations and explain how you would prepare 50
µL of a 4 mg/mL final concentration after dilution in 2X sample
buffer. (Final concentration after mixing with 2X sample should be
4 mg/mL).
b) You are asked to load 20 µg total proteins into a well in
the polyacrylamide gel. How many microlitres of the sample prepared
above should you load onto the gel?

You are performing a Bradford assay. You construct your standard
curve (concentration in mg/mL on the x-axis, Absorbance on the
y-axis) and derive a trendline with an equation of y = 0.25x (the
intercept is set to zero because you blanked your spectrophotometer
correctly). You dilute protein A using the volumes given below, to
a final volume of 1000 μL, and measure the absorbance:
6 μL to 1000 μL = Abs 0.04
80 μL to 1000 μL = Abs 0.15...

2. RDRPkill has a molecular weight of 400. You have a small,
concentrated 500 mM stock solution. a. Express this concentration
in the following units:
i. M
ii. μg/μL
iii. % (w/v)
iv. weight/dL
b. How much of this compound would you have to weigh out if you
were to make up 500 µL of the solution?
c. If you added 5 μL of a 500 mM solution to a cell incubation
with a total volume of 2 mL i....

How many mL of a 100 mg/dL Ferrozine solution are needed to
complex 5.5×10−8 moles of iron?
How many moles of Fe3+ can be reduced by 1.1 mL of 0.216 M
hydroxylamine solution?
As part of this laboratory, you may have to add iron to a solution.
If you have 20 mL of a solution that contains 47 μg dL-1, how many
mL of 500 μg dL-1 iron must be added to reach a concentration of
150 μg dL-1?

1. If I have 100 mL of a 0.15 M NaOH solution and I dilute the
solution to a final volume of 250 mL, what will the molarity of the
diluted solution be?
2. If I add 25 mL of water to 125 mL of a 0.15 M NaOH solution,
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3. I have 345 mL of a 1.5 M NaCl solution. If I boil the water
until the volume of the...

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5. We add 250 µL of 312.5 mg/mL tetracycline into test tube 1, mix
the content well, then remove 250 µL of the solution from test tube
1 to test tube 2, and repeat the procedure until...

. Assume you have 200 mL of a riboflavin stock solution at a
concentration of 50 mg/L and you want to dilute this to a final
concentration of 30 ng/L.
(a) If you wanted a final total volume of 100
mL, how much of your original stock solution are you going
to have to use? Show your work.

a) What volume of a 6.40 M stock solution do
you need to prepare 500. mL of a
0.0347 M solution of HNO3?
b) The absorbance of a cationic iron(II) sample solution was
measured in a spectrophotometer, but the instrument returned an
error because the absorbance was too high. The sample was then
diluted by using a pipette to take 100.0 μL of the sample
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(total volume is 2.00 mL +...

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