Why are plasmids powerful biotechnology tools? Plasmids are extraordinarily useful in the manipulation of genes because they are essentially tiny, self-contained genomes. A plasmid can be moved from cell to cell easily. They also contain the genes that control their own replication. Therefore they can be used to move and to copy any gene that can be inserted into the plasmid. Plasmids also do not usually have detrimental effects on their host cells.