Morphology
Cocci - spherically shaped bacteria with rigid cell walls
Bacilli - rod-shaped bacteria with rigid cell walls
Spirals - elongated, helical bacteria
Pleomorphic - without shape, can stretch and contort similar to an ameba
Prokaryotic characteristics - prokaryotes have a cell wall and no membrane-bound organelles.
Cells arrange themselves in specific forms. For example, the common gram-positive bacteria streptococcus arrange themselves in single file while staphylococcus tend to clump together. These arrangements are part of the bacteria's nature and are helpful in identification.
Another aspect of bacterial morphology has to do with appendages called flagella. These arm-like extentions are made up of microtubules and, using energy supplied by ATP, move in wave-like motions. Microtubules are arrangements of cross-linked a- and b-tubulin, plus other proteins.
The main functions of flagella include movement and transport of food molecules over the cell. Bacteria can have a variety of types and number of flagella. Short flagella-like structures that cover cells are known as cilia.
Monotrichous - one flagellum
Lophotrichous - more than one flagellum on one side of the cell
Amphitrichous - more than one flagellum on opposite sides of the cell
Peritrichous - several flagella that cover the cell (cilia)
