What method allows for the transfer of plasmid genes between two bacteria by forming bridges?

The correct answer is conjugation, which is a process where genetic material is transferred between bacteria using direct contact. In conjugation, a donor bacterium possesses a plasmid, which is a small circular piece of DNA separate from chromosomal DNA. This donor forms a physical connection with a recipient bacterium through a structure called a pilus, creating a bridge-like connection.

During this process, the plasmid DNA can be replicated and transferred through the pilus into the recipient. This method not only facilitates the direct transfer of plasmid genes but also often includes additional genetic material that can confer beneficial traits, such as antibiotic resistance.

Transformation, while notable for its role in genetic exchange, involves the uptake of free DNA from the environment rather than physical contact between bacteria. Transduction also involves gene transfer, but it utilizes bacteriophages (viruses that infect bacteria) to carry genetic material from one bacterium to another. Replication refers to the process of copying DNA and is not related to the transfer of genetic material between different bacterial cells.