Final answer:
In the formation of recombinant DNA, restriction endonucleases are used to create sticky ends on DNA fragments, which then anneal due to complementary base pairing and are finally joined together by DNA ligase to form a stable recombinant molecule.
Step-by-step explanation:
In the process of forming recombinant DNA, unrelated DNAs with similar "sticky ends" are created using a type of enzyme known as a restriction endonuclease. These enzymes cut the DNA molecules at specific recognition sites, creating overhangs known as "sticky ends" that are complementary and can form hydrogen bonds with each other. Once two DNA fragments with matching sticky ends are combined, they can be covalently linked into a continuous strand by the enzyme DNA ligase. This is a fundamental technique in molecular biology used to splice together DNA from different organisms, creating a new molecule with a unique combination of genetic information.
Restriction enzymes generate sticky ends on both the foreign DNA fragment and the plasmid vector, facilitating the annealing of their complementary sequences. DNA ligase then works to ligate the sugar-phosphate backbones of the DNA fragments, forming a stable recombinant DNA molecule that can be further used in various biotechnological applications, such as cloning. This process of forming hydrogen bonds between complementary sequences on single strands to form double-stranded DNA is known as annealing.