The bacterial cell is a typical prokaryotic cell.
Bacterial cell types on the basis of shape:
- Coccus: spherical. E.g., Monococcus, Diplococcus, Streptococcus (chain like), Staphylococcus (in bunches) & Sarcina (cube).
- Bacillus: rod shape.
- Vibrio: comma shaped.
Gram staining of bacteria:
- Bacterial cells are stained with Gram stain (crystal violet & 5% iodine).
- Cells become blue/purple.
- Washed with 95% alcohol/acetone.
-Bacteria that retains color is Gram +ve.
-Bacteria that loses color is Gram -ve.
Prokaryotic cell structure:
- Primitive nucleus. A single circular DNA associated with polyamines is present at the center. Also, referred as genophore or incipient nucleus.
- Outer protective covering that includes cell wall, cell membrane & Glycocalyx.
- Cell wall: made of peptidoglycan (murein). It is made of alternating units of N-acetyl glucosamine & N-acetyl muramic acid. Provide rigidity to the cell & provides shape.
- Cell membrane: made of phospholipid bilayer & proteins. They act as permeability barriers. Sterol like Hopanoids present.
- Glycocalyx: made of polysaccharides.
- Capsule is thick & tough. It is impermeable & prevents bacteria from drying and phagocytosis.
- Slime layer occurs as a loose sheath. It helps in attachment of bacteria to other cells.