What is the function of pili in bacterial cells?

Pili are hair-like structures on the surface of bacterial cells that play a crucial role in their ability to adhere to surfaces and transfer genetic material. Their primary function is to facilitate attachment to host tissues or other surfaces, which is essential for many bacteria in establishing infections or colonizing specific environments. Additionally, pili can participate in a process known as conjugation, where they assist in the transfer of DNA between bacterial cells. This transfer is significant for horizontal gene transfer, allowing bacteria to share advantageous traits, such as antibiotic resistance.

The other options do not accurately describe the function of pili. Providing energy for the cell relates more to processes like cellular respiration or fermentation. Facilitating photosynthesis is specific to organisms such as plants and certain bacteria with chlorophyll, which pili do not contribute to. Protecting against phagocytosis is generally associated with other structures like capsules or cell walls, rather than pili. These clarifications highlight the specific role of pili in attachment and genetic exchange, underscoring the importance of these structures in bacterial physiology and interaction with their environments.