What is the role of sex pili in bacterial conjugation?

In bacterial conjugation, sex pili play a crucial role in facilitating the transfer of genetic material between two bacterial cells. These specialized hair-like appendages protrude from the surface of the donor bacterial cell. Their primary function is to attach to the recipient cell, bringing the two cells into close proximity. This physical connection is essential for the transfer of plasmids or other genetic elements, allowing for the horizontal gene transfer that is characteristic of conjugation.

Once the sex pili have anchored the cells together, the donor cell can transfer genetic material through a process involving a conjugative pilus, which allows DNA to move from one bacterium to another. This can lead to genetic diversity and the spread of traits such as antibiotic resistance.

The other options describe functions that do not align with the specific role of sex pili in conjugation. For instance, absorbing nutrients typically involves other structures such as transport proteins, while energy provision is managed by cellular metabolism, and killing competing bacteria is more associated with mechanisms like the production of bacteriocins or toxins rather than with the role of sex pili.