Recombinant DNA (rDNA) refers to DNA molecules formed by laboratory methods of genetic recombination, such as molecular cloning, to bring together genetic material from multiple sources, creating sequences that would not otherwise be found in biological organisms.

Steps in Recombinant DNA Technology:

1. Isolation: Extract the DNA containing the gene of interest from an organism.
2. Cutting DNA: Use restriction enzymes to cut the DNA at specific sequences, creating fragments with sticky or blunt ends.
3. Ligation: Combine the DNA fragments with plasmid vectors that have been cut with the same restriction enzymes. The DNA ligase enzyme is used to join the DNA fragments, forming recombinant plasmids.
4. Transformation: Introduce the recombinant plasmids into host cells, such as bacteria, through a process called transformation.
5. Selection: Identify and select the host cells that have successfully taken up the recombinant plasmid by growing them on selective media.
6. Cloning and Expression: Allow the transformed cells to reproduce, cloning the recombinant DNA. The gene of interest can then be expressed, and its product can be harvested.

Use in DNA Fingerprinting: DNA fingerprinting involves comparing DNA samples to identify genetic differences. Recombinant DNA technology aids this process by:

• Generating Probes: Creating DNA probes that can bind to specific DNA sequences in the sample.
• Amplifying DNA: Using recombinant DNA techniques to amplify specific regions of the genome (e.g., using PCR).
• Analyzing Patterns: Comparing the amplified DNA sequences or restriction fragment length polymorphisms (RFLPs) to create a unique DNA profile for identification purposes is useful in forensics, paternity testing, and genetic research.

Recombinant DNA technology thus provides the tools to manipulate and analyze genetic material, forming the backbone of modern genetic fingerprinting techniques.