Final answer:
Viruses and plasmids are critical tools in genetic engineering, serving as vectors to transfer genes between organisms. Modified viruses, known as viral vectors, and circular DNA molecules called plasmids, are used to introduce and replicate foreign DNA in a host organism for various biotechnological purposes.
Step-by-step explanation:
Viruses and plasmids play a crucial role in genetic engineering as vectors used to transfer DNA between organisms. A viral vector is engineered to be non-pathogenic and is capable of targeting specific cell types for gene introduction. On the other hand, a plasmid, which is an autonomously replicating circular DNA molecule found in bacteria, can incorporate foreign DNA. This recombinant plasmid can then be inserted into a bacterial host, where it can proliferate, passing the introduced gene along as the bacteria replicate.
Plasmids have natural features such as antibiotic resistance which can be harnessed in the laboratory. Scientists modify plasmids to contain multiple cloning sites (MCS), which allow for the precise insertion of foreign DNA using restriction endonucleases and DNA ligase, enabling the creation of recombinant DNA molecules. The transformation of bacterial cells with plasmids is fundamental in the production of substances like insulin and human growth hormone.
Molecular cloning techniques depend on these vectors to replicate or express specific genes within a host organism. This process is central to modern biotechnological applications, including the study of gene function and the manufacture of gene products.