Final answer:
A self-transmissible plasmid can independently transfer itself to another bacterial cell through conjugation, while a mobilizable plasmid requires assistance from a self-transmissible plasmid's transfer machinery to move to another cell.
Step-by-step explanation:
The difference between a self-transmissible plasmid and a mobilizable plasmid lies in their mechanisms for transfer between bacterial cells. Self-transmissible plasmids, like the F (fertility) plasmid, contain all the necessary genes for bacterial conjugation and can independently initiate the transfer of their DNA to another bacterial cell. Mobilizable plasmids, on the other hand, lack some of these genes and therefore require the presence of a self-transmissible plasmid within the same cell to facilitate their transfer.
During the process of bacterial conjugation, a self-transmissible plasmid directly orchestrates the formation of a conjugative pilus and the subsequent DNA transfer to a recipient cell. Conversely, a mobilizable plasmid relies on the machinery provided by a co-resident self-transmissible plasmid to hitchhike during the conjugation process. This distinction is crucial for understanding the spread of antibiotic resistance genes, as it dictates the potential for plasmids to disseminate these genes within and across bacterial populations.