Difference Between Gram-positive and Gram-negative Bacteria

Bacteria

Bacteria are a large group of microscopic, unicellular organisms and have been grouped into prokaryotic, which means the absence of the nucleus and they have a simple internal structure, including capsule, cell wall, DNA, Flagellum, Pilli, Cytoplasm, and Ribosomes. They exist in every place around us and are present in communities of millions. In length, the complete bacteria measure only a few micrometers.

A bacterium is a singular word for bacteria. The study of bacteria is known as bacteriology and it’s a branch of microbiology.

Types of Bacteria

Types of Bacteria

There are several different types of bacteria and are mainly classified by their:

  • Shapes: coccus, Bacillus, Vibrio, spirillum or spirochete.
  • Cell wall composition: Gram-positive and Gram-negative.
  • Nutritional Patterns: Autotrophic or heterotrophic.
  • Mode of Respiration: Aerobic or Anaerobic.

Here, let us explore more information about the difference between Gram-positive and Gram-negative bacteria.

Difference between Gram-positive and Gram-negative Bacteria

Difference between Gram-positive and Gram-negative Bacteria

Gram-positive bacteria Gram-negative bacteria
Cell Wall Smooth and single layered Wavy and double layered
Cell Wall thickness 20 to 80 nanometres 8 to 10 nanometres
Peptidoglycan Layer Thick Thin
Teichoic acids Present Absent
Outer membrane Absent Present
Porins Absent Occurs in Outer Membrane
Mesosome It is more prominent. It is less prominent.
Morphology Cocci or spore-forming rods Non-spore forming rods.
Flagella Structure 2 rings in basal body 4 rings in basal body
Lipid content Very low 20 to 30%
Lipopolysaccharide Absent Present
Toxin Produced Exotoxins Endotoxins or Exotoxins
Resistance to Antibiotic More susceptible More resistant
Examples- Staphylococcus, Streptococcus, etc. Escherichia, Salmonella, etc.
Gram staining characteristics

These bacteria retain the crystal violet color even after they are washed with acetone or alcohol and appear as purple colored when examined under the microscope after gram staining.

These bacteria do not retain the stain color even after they are washed with acetone or alcohol and appear as pink colored when examined under the microscope after gram staining.

For more information on various topics like Bacteria and Bacterial Diseases, visit BYJU’S.


Practise This Question

Incomplete breakdown of sugar in anaerobic respiration forms ____.