With the help of a schematic diagram only, show in three steps, the formation of recombinant DNA by the action of restriction endonuclease EcoRI and DNA ligase.

The correct answer is the schematic diagram illustrating the three-step formation of recombinant DNA through the actions of the restriction endonuclease EcoRI and DNA ligase.

As shown in the provided schematic diagram, the process occurs in three main steps:

Step 1: Cleavage by Restriction Enzyme (EcoRI)
The restriction endonuclease EcoRI recognizes the specific palindromic sequence 5'-GAATTC-3' on both the Vector DNA (on the left) and the Foreign DNA (on the right). As indicated by the arrows pointing between the G and A bases, the enzyme cuts both double-stranded DNA molecules at these exact positions on opposite strands, slightly away from the center of the palindrome.

Step 2: Generation of Sticky Ends
Cleavage results in single-stranded overhanging sequences at the cut sites, labeled as Sticky end in the diagram. The vector DNA is left with an overhanging 3'-TTAA-5' sequence, while the foreign DNA is left with a complementary overhanging 5'-AATT-3' sequence. These sticky ends can easily form hydrogen bonds with their complementary counterparts.

Step 3: Ligation by DNA Ligase
The complementary sticky ends of the vector DNA and foreign DNA pair up. The enzyme DNA Ligase is then introduced to catalyze the formation of phosphodiester bonds, sealing the sugar-phosphate backbones of the two DNA molecules. This joins them together to form the hybrid molecule labeled as Recombinant DNA at the bottom of the diagram.