here is a part of the protocol we did:

a)spin down the chloroplast solution and decant the supernatant. add 4ml water to the pellet.

b) add 10ul proteinase K ( concentration= 20mg/ml) to get a final concentration of 50ug/ml.

-> how do they get 10ul? which formula do they use? i don't think that they use the dilution formula (C1 XV1= C2 X V2) since we don't know the total volume of the solution. it can't be 4ml, because when we add proteinase K the volume of the solution will increase.

c) then add slowly 0.25ml 10% or 0.125ml 20% SDS to get a final concentration of 0.5% SDS.

-> again, how do they come to 0.25ml 10% or 0.125ml 20% SDS to get a final concentration of 0.5% SDS?

i am very stucked, please *delete me*