Final answer:
Plasmids are a common vector used for cloning genes. They carry the inserted gene and replicate within a bacterial host, enabling the proliferation of the cloned gene. Bacteriophages can also serve as vectors.
Step-by-step explanation:
A common vector used for cloning genes is plasmids. Plasmids are small circular DNA molecules that replicate independently of the chromosomal DNA in bacteria. They act as a "folder" for inserting a desired DNA fragment and are essential in the process of creating recombinant DNA. These plasmids are then introduced into a bacterial host for proliferation, allowing the gene to be copied or cloned within the bacterium. As the host cell divides, the recombinant DNA is also copied and proliferated which is a crucial step in molecular cloning. Examples of plasmids used as vectors for the preparation of recombinant DNA include pMB-9, pBR-322, pBR-325, pKC-7, and many more. Viruses such as bacteriophages can also be used as vectors, especially in gene therapy or when longer inserts of DNA are required.