We have a solution of protein that has a concentration of 0.25 mg/ml. a.We need
ID: 883308 • Letter: W
Question
We have a solution of protein that has a concentration of 0.25 mg/ml.
a.We need 20micrograms of the protein for an experiment. What volume of the protein solution do we need?
b.Suppose we want a solution containing 150 micrograms of the protein at a concentration of 0.50 mg/ml. To do this we will first evaporate the liquid from enough of the protein solution to get 150 micrograms. How much solution do we need to start with? How much H2O do we add to get the desired concentration?
d.Suppose we want 1 ml of a 10 micrograms/ml solution. How much H2O and protein stock must we add to get this?
e.Suppose we want 100 microliters of a 0.1 micrograms/microliters solution. How much H2O and protein stock must we add to get this?
Explanation / Answer
You are given a protein solution with a concentration of 0.25 mg/ml.
a.We need 20 micrograms of the protein for an experiment. What volume of the protein solution do we need?
Solution :- Initial concentration = 0.25 mg / ml
0.25 mg * 1000 ug / 1 mg = 250 ug . (ug = microgram)
Therefore 1 ml solution contains 250 ug of the protein
We want 20 ug protein for the reaction.
We know stock solution is 1 ml = 250 ug
? ml = 20 ug
20 ug * 1 ml / 250 ug = 0.08 ml
Therefore we need 0.08 ml of the 0.25 mg/ml solution.
b.Suppose we want a solution containing 150 micrograms of the protein at a concentration of 0.50 mg/ml. To do this we will first evaporate the liquid from enough of the protein solution to get 150 micrograms. How much solution do we need to start with? How much H2O do we add to get the desired concentration?
Solution :- lets calculate the volume of the solution needed to evaporate to get 150 ug protein
250 ug = 1 ml
150 ug = ? ml
150 ug * 1 ml / 250 ug = 0.6 ml
Therefore 0.6 ml of the original solution needed to evaporate to get 150 microgram of the protein
Now we want concentration 0.5 mg / ml,
150 ug * 1 mg / 1000 ug = 0.15 mg
We want 0.5 mg/ ml
So 0.5mg per ml = 0.15 mg / ml
ml = 0.15 mg /0.5 mg per L = 0.3 ml
So we need to add 0.3 ml of water to get 0.5 mg/ ml
d.Suppose we want 1 ml of a 10 micrograms/ml solution. How much H2O and protein stock must we add to get this?
Solution :-
We have 250 ug / ml solution and we want 1 ml of the 10 ug per ml solution.
So lets calculate the volume of the 250 ug per ml solution needed
250 ug = 1 ml
10 ug = ? ml
= 10 ug * 1 ml / 250 ug
= 0.04 ml
So we need to use 0.04 ml of the stock solution and dilute it total volume of 1 ml so volume of water needed to be add is 1 ml – 0.04 ml = 0.96 ml
e.Suppose we want 100 microliters of a 0.1 micrograms/microliters solution. How much H2O and protein stock must we add to get this?
Solution :-
0.25 mg / ml is nothing but 0.25 microgram per microliter
So we want 0.1 microgram per microliter
0.25 ug = 1 uL
0.1 ug = ? uL
= 0.1 ug * 1 uL / 0.25 ug
= 0.4 uL
So we need to use the 0.4 microliter of the stock solution and amount of water needed to get 100 microliter is
100 uL – 0.4 uL = 99.6 uL
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