explain why sometimes the supernatant is found in the DNA and other times it is in the pellet

Question

 need help on this college biology question

Answer 1

I think that question is worded improperly, supernatant is liquid on the top of pellet and it is always separate from pellet.

 

I think the question is:

explain why sometimes the DNA   is found in the supernatant and other times it is in the pellet

 

Ideally DNA needs to be precipitated with pellet and should not remain in supernatant. DNA is acidic in nature and therefore, needs optimum salt concentration in the buffer to be pelleted from a solution. At very low salt concentration or without salt DNA would remain in supernatant. This is why the supernatant is saved to add more salt and reprecipitate DNA if there is no pellet or there is negligible amount of DNA in the pellet.

 

Hope this helps.