if i have a tube containing dna with the conc of 25 mg/ml and i remove 1ul from that tube into a new tube and add 999ul of dh20 into the new, how much dna do i

Question

if i have a tube containing dna with the conc of 25 mg/ml and i remove 1ul from that tube into a new tube and add 999ul of dh20 into the new, how much dna do i have in my new tube?

Answer 1

25 mg/ml is the same as 25 mg/1000 ul

Taking 1 ul you are taking 1/1000 of the total = 0.025 mg DNA

Done another way:  25 mg/1000 ul = 0.025 mg/ul x 1 ul = 0.025 mg DNA

This is how much DNA will be transferred to the new tube.  Now, if you are actually asking what is the final concentration of DNA in the new tube, it will be ....

0.025 mg DNA/ 1000 ul = 0.025 mg/ml

 

You could also look at this problem as you are making a 1000 fold dilution of the original solution, i.e. you are diluting 1 ul of the 25 mg/ml to 1000 ul of final solution.  Thus, the final concentration will be 1 thousandths of the original concentration, or 0.025 mg/ml.

Answer 2

JRS has provided an answer to the OTHER IDENTICAL (I believe) question that you sumitted.