How can purified $DNA$ be precipitated from a solution after appropriate treatment?

Who discovered $PCR$ (Polymerase Chain Reaction)?

The Polymerase Chain Reaction $(PCR)$ is a reaction in which amplification of specific $DNA$ sequences is carried out in vitro. This statement is

Describe briefly the following:
$(a)$ Origin of replication
$(b)$ Bioreactors
$(c)$ Downstream processing

When $DNA$ fragments stained with ethidium bromide are viewed under $UV$ radiation,how do they appear?

Palaeontologists unearthed a human skull during excavation. $A$ small fragment of the scalp tissue was still attached to it. Only a little $DNA$ could be extracted from it. If the genes of the ancient man need to be analysed,the best way of getting a sufficient amount of $DNA$ from this extract is: