Microbiology Practice Exam

What distinguishes pili from fimbriae in bacterial cells?

1. Pili are for attachment, while fimbriae are for motility

2. Pili are involved in bacterial conjugation, while fimbriae are for attachment

3. Pili are short and numerous, while fimbriae are long and few

4. Pili are used for DNA reception, while fimbriae are for nutrient absorption

The correct answer is: Pili are involved in bacterial conjugation, while fimbriae are for attachment

Pili and fimbriae are both surface appendages found on bacterial cells, but they serve distinct functions that highlight their differences. The correct choice states that pili are primarily involved in bacterial conjugation, a process where genetic material is transferred between bacterial cells. This transfer can contribute to genetic diversity and the spread of traits such as antibiotic resistance. In contrast, fimbriae are short, hair-like structures that predominantly function to facilitate attachment to surfaces or other cells. This attachment is crucial for the colonization of bacteria in various environments, including host tissues. The other proposed options do not accurately reflect the roles and characteristics of these structures. For instance, while both pili and fimbriae can assist with attachment, only pili have a specialized role in conjugation. Furthermore, pili are not necessarily used for DNA reception nor are they inherently longer or fewer than fimbriae; rather, they are often longer than fimbriae but present in fewer numbers. Understanding these functional differences helps clarify the significance of each structure in bacterial physiology and interactions.