EVERYDAY SCIENCE

Detailed explanation-1: -Two types of surface appendage can be recognized on certain bacterial species: the flagella, which are organs of locomotion, and pili (Latin hairs), which are also known as fimbriae (Latin fringes). Flagella occur on both Gram-positive and Gram-negative bacteria, and their presence can be useful in identification.

Detailed explanation-2: -Two morphological types of appendages, an anchor-like appendage and a peritrichate fibril-type appendage, have been observed on cells of an adhesive bacterium, Acinetobacter sp.

Detailed explanation-3: -Flagella are helical appendages that protrude through the cell membrane and are long and whip-like. Pili are hollow filamentous extensions that emerge from the cell’s surface.

Detailed explanation-4: -Flagellin is a structural protein of the flagellum, a surface filament dedicated to bacterial motility. The flagellar filament is composed of as many as 20, 000 subunits of flagellin. In pathogenic bacteria, flagella and chemotaxis machinery contribute to virulence.

Detailed explanation-5: -Based on their arrangement, bacteria are classified into four groups: monotrichous (having one flagellum), amphitrichous (single flagellum at both ends), lophotrichous (numerous flagella as a tuft), and peritrichous (flagella distributed all over the cell except at the poles).