# calculating nunber of copies of synthetic RNA oligo - (Apr/11/2008 )

Hello all,

I am hoping somebody can help me.

I am trying to work out how many copies (molecules) of a 23-mer RNA oligo I have in a solution, so I can use it to create a standard curve to extrapolate the copy number of the same RNA species expressed endogenously in a cell line.

If I have my synthetic RNA at X Molar concentration (I also know the molecular weight, and micrograms), how do I calculate how many actual molecules (or copies) I have in say 1microlitre, at that concentration?

Is the C=(N/A)/V equation what I use? where C is molar concentration, N is the number of molecules, V the volume in L and A is Avogardo's constant.

I am very confused, and can't find any sites online that calculate such things.

Many thanks for any help in advance!

Sheena

i mole is avogadro's number (6.02x10e23) of molecules.

if you know the molar concentration then you can figure out how many molecules in 1ul.

for example, you have a 1M solution. that has 6.02x10e23 molecules in 1 liter, 6.02x10e20 molecules in 1ml and, finally, 6.02x10e17 molecules in 1ul.