Final answer:
Annealing of cohesive ends of bacteriophage lambda DNA allows for the formation of hydrogen bonds between complementary bases, which results in the joining together of single strands of DNA.
Step-by-step explanation:
Annealing of cohesive ends of bacteriophage lambda DNA allows for the formation of hydrogen bonds between complementary bases on single-stranded DNA sequences.
This process of annealing enables the joining together of two single strands of DNA, either with sticky ends or blunt ends.
DNA ligase is then able to permanently rejoin the sugar-phosphate backbones of the DNA, creating a continuous double-stranded molecule.