They are able to sense the presence of certain nutrients in their environment and move toward them and they are able to move away from harmful substances. Large cocci with three-dimensional planes of cell division, giving regular packets of cells, typical of Staphylococcus. Using flagella, bacteria are able to respond to environmental stimuli. There are three basic shapes of bacteria: coccus, bacillus, and spiral. Bacteria can have multiple flagella that surround the cell, a few flagella on one or both ends of the cell, or a single flagella.

These structures move in a circular motion to propel the bacteria forward. Some, but not all, bacteria have one or more flagella. (2) Bacteria are categorized based on their shapes into three classes: cocci (spherical-shaped), bacillus (rod-shaped) and spirochetes (spiral-shaped) cells. Because it has no cell wall it can have a variety of shapes.ģ) flagella –a whip-like structure used for movement. A coccus (plural cocci) is any bacterium or archaeon that has a spherical, ovoid, or generally round shape. Mycoplasma pneumoniae is an example of a cell wall-less bacteria. They have, instead, chemical compounds which protect the bacteria against drying out and they usually live in environments in which osmotic pressures are not a problem for survival. Generally speaking, a coccus (plural cocci) refers to a bacteria or archaeon that has a spherical, ovoid, or round form in general.

The term cocci, which means sphere, indicates the. The term cocci, which means sphere, indicates the bacteria are generally round. coli (stained pink).Ī few bacteria do not have cell walls. Gram-positive cocci are circular or oval in shape. of Bacteria and Archaea exist in three major mor- phological forms: spherical (coccus), rod-shaped (bacillus) and spiral-shaped (spirillum) (Figure 2a-c). The image at the left as seen through a microscope shows both Gram-positive (stained dark purple) rod-shaped bacteria, Bacillus cereus, and the smaller Gram-negative rod-shaped bacteria E.

Bacteria shapes cocci