Final answer:
Recombinant DNA is a combination of DNA from two different sources used in biotechnology, especially in the field of gene cloning and genetic engineering, to produce proteins like insulin and create transgenic crops.
Step-by-step explanation:
DNA molecules that contain pieces of DNA from two different sources are defined as recombinant DNA. This technology allows for a human gene, for instance, to be inserted into bacterial DNA. It plays a pivotal role in biotechnology and is instrumental in gene cloning and identifying gene functions. A typical process would include using a vector, such as a bacterial plasmid, to carry the recombinant DNA into a host cell where it can replicate and perhaps express a protein useful in medicine or research, like insulin. This has vast applications, including the creation of transgenic crops and gene therapy.