What structure allows bacteria to transfer genetic material during conjugation?

The structure that allows bacteria to transfer genetic material during conjugation is the pilus. A pilus is a hair-like appendage found on the surface of many bacteria. It primarily serves as a bridge between two bacterial cells during the process of conjugation. In this process, one bacterium forms a conjugation pilus to connect to a recipient cell, allowing for the direct transfer of genetic material, typically in the form of plasmids.

This transfer of genetic information is crucial for processes such as antibiotic resistance and adaptation, helping bacteria evolve and survive in various environments. While plasmids are involved in conjugation as the vectors of genetic material being transferred, they do not facilitate the actual connection between the bacterial cells; that role belongs to the pilus. Other structures like the capsule and flagellum serve different functions, such as protecting cells or facilitating movement, but they do not play a direct role in the conjugative process itself.