Structure of Bacterial Cells

Bacteria (singular-bacterium) are unicellular (single cell) microorganisms, and have a simple cell structure consisting of:

  1. Cytoplasm contais the bacterial chromosome, ribosomes, stored energy inclusions, and often plasmids.
  2. Cytoplasmic membrane and mesosomes
  3. Cell wall (except bacteria with deficient cell walls such as Mycoplasma)
  4. External structures such as capsule, fimbriae (pili), and flagella, depending on the species.
  5. Some bacteria such as Bacillus and Clostridium also produce endospores in unfavorable environmental conditions.

Bacterial cell structure

Cell Wall–Deficient Bacteria

Cell Wall–Deficient Bacteria

Although most prokaryotes cannot survive in nature without their cell walls, some do so naturally. For example, mycoplasma and thermoplasma.

Plasmids: Properties, Types, and Functions

Plasmids: Properties, Types, and Functions

Plasmids are extra-chromosomal genetic elements that replicate independently of the host chromosome. The codes for drug resistance, virulence

Gram-Positive vs. Gram-Negative Bacteria

Gram-Positive vs. Gram-Negative Bacteria

Gram positive bacteria appear purple and gram-negative bacteria appear pink when stained by Gram-staining methods.

Peptidoglycan: Structure, Function

Peptidoglycan: Structure, Function

Peptidoglycan consists of carbohydrate backbone composed of alternating units of NAG and NAM molecules attached through β-1,4-glycosidic bonds.

Transposons: Definition, Types, Functions

Transposons: Definition, Types, Functions

Transposons, also called 'jumping genes' are mobile genetic elements. Barbara McClintock got Nobel Prize for the study of transposons.

Cytoplasmic Granules in Bacteria

Cytoplasmic Granules in Bacteria

Concentrated deposits of certain substances which are presented/located in the cytoplasm of certain bacteria.

Teichoic Acid: Structure, Functions

Teichoic Acid: Structure, Functions

Teichoic acids are fibers of glycerol phosphate or ribitol phosphate and is located in the cell-wall of gram-positive bacteria.

Lipopolysaccharide (LPS) Layer

Lipopolysaccharide (LPS) Layer

Lipopolysaccharide (LPS) layer also called the outer membrane is the outermost layer present in the cell wall of gram-negative bacteria.

Bacterial Pili (Fimbriae): Types, Functions

Bacterial Pili (Fimbriae): Types, Functions

Pili or fimbriae are hair-like filaments that help pathogen in adherence to host cells. Sex pili play role in conjugation.

Differences between Exotoxins and Endotoxins

Differences between Exotoxins and Endotoxins

Bacterial toxins are broadly divided into two general categories: exotoxins (secreted outside the cell) and endotoxins (LPS).

Flagella: Structure, Arrangement, Function

Flagella: Structure, Arrangement, Function

Flagella are long, whiplike appendages that move the bacteria toward nutrients and other attractants

Bacterial Spores: Structure and Spore-Forming Bacteria

Bacterial Spores: Structure and Spore-Forming Bacteria

Bacterial spores are highly resistant, dormant structures formed in response to adverse environmental conditions

Bacterial Capsule: Importance, Capsulated Bacteria

Bacterial Capsule: Importance, Capsulated Bacteria

Capsule is a gelatinous layer covering the bacterium and is a major virulence factor of S. pneumoniae, H. influenzae, etc.