plz guys help me`?

Question

You are preparing reagents for your dideoxy sequencing project. You want to make a stock solution of ddGTP (514.93 g/mol). How much ddGTP will you need to weigh out to make 1000µl of a 100mM stock?


a.5.15x10-1 grams

b.5.15x10-3 grams

c.5.15x100 milligrams

d.5.15x104 micrograms

Answer 1

This is a complex conversion question, but remember, since it's all metric, it's just a matter of doing it one conversion at a time.

100 mM must be millimoles, so 100mM = .1 M
and
1000 µl = 1 mL

Since:
M = moles/L
moles = M * L = .1 M * .001 L = .0001 moles
514.93 g/mol ddGTP * .0001 moles = .0515 g

.0515 g = 5.15 * 10^-2 g = 5.15 * 10^4 µg (d, solution!)