AP BIOLOGY

Detailed explanation-1: -Pili (Fimbriae): Pili are slender, hairlike, proteinaceous appendages on the surface of many (particularly Gram-negative) bacteria. They are important in adhesion to host surfaces.

Detailed explanation-2: -A key feature that enables adhesion of bacterial cells both to each other and to other surfaces is the short hair-like appendages called fimbriae (singular fimbria), which are found on most Gram-negative bacteria and on some Gram-positive bacteria [9–11].

Detailed explanation-3: -Thin, hairlike appendages, 1 to 20 microns in length and often occurring in large numbers, present on the cells of gram-negative bacteria, particularly Enterobacteriaceae and Neisseria.

Detailed explanation-4: -Pili are longer than fimbriae. Occurrence of the fimbriae in each cell is about 200-400 while the occurrence of pili are lesser than one to ten every cell. Fimbriae are found in both the gram-negative and positive bacteria both, pili are present in the gram-negative bacteria only.

Detailed explanation-5: -Fimbriae are long filamentous polymeric protein structures located at the surface of bacterial cells. They enable the bacteria to bind to specific receptor structures and thereby to colonise specific surfaces.