The cell wall is the outermost and non-living part of the cell. It is present in plant cells, fungi, bacteria and algae. The cell wall is thick, rigid, and has elastic properties that help them to grow in thickness over a period of time. The cell wall is metabolically inactive as it lacks receptors and is mainly involved in
- Providing a fixed shape to the cell.
- Protecting the cell from the external environment.
- Acting as a barrier between the external and internal environment.
Also Refer: Cell wall
Based on the thickness of the cell wall, the bacteria are classified as Gram-positive and Gram-negative bacteria. They can be differentiated by gram staining.
Gram-positive bacteria are a group of heterogeneous bacteria, which appear purple in colour when they are stained by gram staining and examined under a microscope. Clostridium, Actinomyces, Mycobacterium, Nocardia, Streptococci, and Staphylococci, are a few examples of gram-positive bacteria.
Gram-negative bacteria are a group of heterogenous bacteria, which appear pink in colour when they are stained by gram staining and examined under a microscope. Vibrio, Campylobacter, Pseudomonas are a few examples of gram-negative bacteria.
Also Read- Difference Between Gram-positive and Gram-negative Bacteria
Here, let us explore more information about the difference between gram-positive and negative cell walls.
Cell Wall of Gram-positive and Gram-negative Bacteria – Differences
Gram-Positive Cell Wall Vs Gram-Negative Cell Wall
| Gram-Positive Cell Wall | Gram-Negative Cell Wall |
| Layers | |
| Single layered | Double layered |
| Composition | |
| Consisting of several layers of peptidoglycan | Consisting of a single layer of peptidoglycan |
| Thickness | |
| 15 to 80 nanometers | 10 nanometers |
| Periplasmic space | |
| Small | Large |
| Outer membrane | |
| Absent | Present |
| Teichoic Acid | |
| Present | Absent |
| Porins | |
| Absent | Present |
| Lipid Content | |
| Very low (2 – 5 per cent) | High (15-20 per cent) |
| Lipopolysaccharides | |
| Absent | Present |
| Gram staining Procedure | |
| Retains the crystal violet dye and appear purple in colour | Does not retain the crystal violet dye and appear pink in colour |
These differences between the Cell Wall of Gram-positive and Gram-negative Bacteria are classified based on their structure, composition of the cell and by the procedure of Gram staining technique.
This was a brief introduction to the difference between gram-positive and negative cell wall. Stay tuned with BYJU’S to learn more in detail about the various topics like Bacteria and Bacterial Diseases at BYJU’S Biology.
Frequently Asked Questions on Difference Between Gram-Positive and Negative Cell Wall
What is gram staining? How do the Gram-Positive and Negative bacteria look under gram stain?
Gram staining is a differential staining technique that differentiates between gram-negative and gram-positive groups by colouring these cells purple or pink. As a result of the presence of a thick layer of peptidoglycan in its cell walls, gram-positive bacteria stain purple, by retaining the crystal violet that these cells get stained with. Due to the thin layer of peptidoglycan, the gram-negative bacteria appear pink after staining with safranin.
What is the significance of gram-negative bacteria?
Gram-negative bacteria are involved in causing various pathogenic diseases. They are also resistant to certain antibiotics due to the presence of the lipopolysaccharide layer.
Give some examples of gram-positive bacteria.
Clostridium, Actinomyces, Mycobacterium, Nocardia, and Staphylococci, are a few examples of gram-positive bacteria.
What is characteristic of the cell walls in gram-positive bacteria?
The cell wall of gram-positive bacteria consists of several layers of peptidoglycan and also contains tecoic acid.
What are the components of the gram-negative bacterial cell walls?
The cell wall of gram-negative bacteria consists of a single layer of peptidoglycan and has a layer of outer-membrane consisting of lipopolysaccharide, membrane proteins and porins.
