Molecular cloning steps in order include:

A、extraction of vector DNA, ligation of target DNA to vector DNA, restriction of target DNA;

B、restriction of target DNA, ligation of cut (that is, restricted) target DNA to vector DNA which has already been cut, transformation of host cells;

C、cutting target DNA, cutting vector DNA, amplifying target DNA;

D、amplifying target DNA, ligating target DNA to cut vector DNA, homologous recombination of target and vector DNA