What are Some Structural Characteristics of Bacteria?
Bacterial structures have no chloroplasts or mitochondria, and most of them cannot perform photosynthesis. Some bacteria (such as cyanobacteria) have chlorophyll on their cell membranes for photosynthesis.
Bacterial structure
Bacterial structure capsule
- The outermost surface of many bacteria in the capsule is also covered with a layer of polysaccharides. The boundary is clearly called a capsule, such as pneumococcus, and the boundary is not clearly called a slime layer, such as staphylococcus. Capsules are of great significance to the survival of bacteria. Bacteria can not only use capsules to defend against adverse environments, protect themselves from being swallowed by white blood cells, but also selectively adhere to the surface of specific cells, showing a specific attack on target cells. ability. For example, Salmonella typhi can specifically intestinal lymphoid tissues. The capsular fibril bacteria can also store the digestive enzymes secreted by the bacteria in order to attack target cells.
Bacterial structure flagella
- Flagella is a motor organ of some bacteria. It is composed of an elastin called flagelin, which is structurally different from flagella of eukaryotes. Bacteria can change the state of motion by adjusting the direction of flagella rotation (clockwise and counterclockwise).
Bacterial structure pili
- Fimbriae are thinner, shorter, and stiffer filaments than the flagella on the surface of some bacteria, which must be observed with an electron microscope. The characteristics are: thin, short, straight, hard, and more, pilus has nothing to do with the movement of bacteria, according to the shape, structure and function, can be divided into two types of ordinary pili and sexual pili. The former is related to bacterial adsorption and infection of the host, and the latter is a hollow tube, which is related to the transmission of genetic material.
Bacterial structure cilia
- Ciliates are mobile protrusions that protrude from the surface of some eukaryotic cells.