- Eubacteria or simply bacteria are the true bacteria.
- These are cosmopolitan i.e. they can be found everywhere
- Bacteria have a cell envelope which includes a cell envelope which consists of glycocalyx ( mucilage covering), cell wall and cell membrane.
- Bacteria have peptidoglycan layers in their cell wall. In this respect, they differ from archaebacteria.
- The cell membrane of bacteria is of phospholipid which is similar to that in eukaryotes.
- They lack membrane-bound cell organelles. Ribosomes of the 70S are present in them.
- The nucleus in them is called nucleoid. Apart from chromosomal DNA, they also possess extrachromosomal DNA such as a plasmid.
- They possess extracellular structures such as flagella, pili, fimbriae on their surfaces.
Shapes of bacteria:
Bacteria can be divided into four types based on the shape
- Coccus - About spherical and always non-flagellate. They can be Monococcus ( occur singly), Diplococcus ( occur in pairs), Streptococcus ( occur in chains), Staphylococcus ( irregular clusters), Sarcina ( geometrical forms) etc.
- Spirillum - Coiled forms giving the spiral appearance. Eg. Spirillum minus
- Bacillus - Rod-shaped with rounded or blunt ends. E.g. Monobacillus, Diplobacillus etc.
- Vibrio - Little less than one complete twist or turn resembles comma (,). E.g. Vibrio cholera
Structure of bacterial cell
A bacterial cell consists of a cell envelope, cytoplasm, nucleoid, plasmids, inclusion bodies, flagella, pili and fimbriae.
