calculation help - (Mar/03/2008 )
Hi there,
Ive got a lab tomorrow and as Im going over the instructions something is confusing...
so we have to create a dilution series from a known stock concentration of DNA..
so to tube (1) it says to add 10u 1 of stock DNA (100ng/uL) to this tube...what i am confused about is when it says 10u (does it actually mean 10uL and is it just a printing error?)...and is the conc. of the DNA 100ng/uL meaning in 1uL of solution there is 100ng of DNA 
...
ok then it says to another tube (A) add 2u 1 stock of DNA and 18uL of water to this tube
then to tube 2 add 10u 1 from tube A
to tube B add 2u 1 from tube A and 18u 1 of sterile water to this tube
to tube 3 add 10u 1 from tube B
to tube C add 2u 1 from tube B and 18u 1 water to this tube
to tube 4 add 10u 1 from tube C
then to tubes 1-4 add 2uL of gel loading dye
okkk so i get all thaaat (assuming that the printing error is correct from wat i wrote above)??? now I have to calculate the conc. in each of the tubes 1-4...and im not sure if im doing it right? can someone please tell me if ive done this correctly?
im thinking this how you do it. (for tube 2 which is essentially tube A)---10uL*100ng/uL divided by 12uL=83.33ng/uL
hence tube 3 would be 83.33*10/12???
Cheers,
biology_06er
Ive got a lab tomorrow and as Im going over the instructions something is confusing...
so we have to create a dilution series from a known stock concentration of DNA..
so to tube (1) it says to add 10u 1 of stock DNA (100ng/uL) to this tube...what i am confused about is when it says 10u (does it actually mean 10uL and is it just a printing error?)...and is the conc. of the DNA 100ng/uL meaning in 1uL of solution there is 100ng of DNA
...ok then it says to another tube (A) add 2u 1 stock of DNA and 18uL of water to this tube
then to tube 2 add 10u 1 from tube A
to tube B add 2u 1 from tube A and 18u 1 of sterile water to this tube
to tube 3 add 10u 1 from tube B
to tube C add 2u 1 from tube B and 18u 1 water to this tube
to tube 4 add 10u 1 from tube C
then to tubes 1-4 add 2uL of gel loading dye
okkk so i get all thaaat (assuming that the printing error is correct from wat i wrote above)??? now I have to calculate the conc. in each of the tubes 1-4...and im not sure if im doing it right? can someone please tell me if ive done this correctly?
im thinking this how you do it. (for tube 2 which is essentially tube A)---10uL*100ng/uL divided by 12uL=83.33ng/uL
hence tube 3 would be 83.33*10/12???
Cheers,
biology_06er
first things first. there is a typo in the presentation. the typist separated the u from the l in ul (ie u 1) using the 1 key for the l key (the opposite used to be done when using a typewriter without a 1 key).
now for the dilution series...
the stock (tube 1) contains 100ng in each ul (as you correctly assume).
tube a: take 2ul stock and add 18ul water is a 10x dilution (2ul in a final volume of 20ul). this gives you 10ng/ul. tube 2 is this concentration (you take 10ul from tube a, concentration doesn't change but you have the 10ul that you need for the standard curve)
tube b: take 2ul of tube a and add 18ul water...
i would guess that you can figure the rest.