Question

the fragments from pst1 digest of the ppsu1 plasmid as starting pieces of dna, to which active ligase enzyme is added.

Answer 1

The ligation of the digested insert and the plasmid is performed by pooling both in a single reaction tube and adding DNA ligase enzyme which catalyses the formation of phosphodiester bond between insert and plasmid DNAs, there by forming the recombinant DNA molecule.