What is the difference between gram-positive and gram-negative bacteria cell walls?
Bacteria are microscopic and unicellular organisms. They have prokaryotic cells and they are classified as either gram-positive or gram-negative.
The core difference between gram-positive and the gram-negative bacteria cell wall is that gram-positive bacteria have a cell wall that is smooth and single-layered while gram-negative bacteria have a cell wall which is waxy and double-layered.
What Are Gram-Positive Bacteria?
Gram-positive bacteria have a smooth and single-layer cell wall. They retain crystal violet dye and stain blue or purple during gram reaction.
Examples of gram-positive bacteria are Staphylococcus, Streptococcus, etc.
What Are Gram-Negative Bacteria?
Gram-negative bacteria have a waxy and double-layered cell wall. They can be decolorized to accept counterstain and stain pink or red.
Examples of gram-negative bacteria are Escherichia, Salmonella, etc.
Comparison Chart: Gram-Positive Bacteria Vs Gram-Negative Bacteria Cell Walls
| Basic Terms | Gram-Positive Bacteria | Gram-Negative Bacteria |
| Cell Wall | Smooth and single-layered | Waxy and double-layered |
| Gram Reaction | Retain crystal violet dye and stain blue or purple | Accept safranin and stain pink or red |
| Cell Wall thickness | Measure about 20 to 80 nanometres | Measure about 8 to 10 nanometres |
| Chemical Composition of Cell Wall | Peptidoglycan, Teichoic acid Lipoteichoic acid | Lipopolysaccharide, Lipoproteins, and Peptidoglycans |
| Peptidoglycan Layer | Thicker | Thin |
| Teichoic acids | Presence | Absence |
| Outer membrane | Absent | Present |
| Porins | Absent | Occur in the outer membrane |
| Mesosome | More prominent | 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 |
| Resistance to Drying | Low | High |
| Inhibition by Basic Dyes | Low | High |
| Nutritional Requirements | Relatively Complex | Relatively Simple |
| Antibiotic Resistance | More susceptible to antibiotics | More resistant to antibiotics. |
| Examples | Staphylococcus, Streptococcus, etc. | Escherichia, Salmonella, etc |
Core Differences between Gram-Positive and Gram-Negative Bacteria Cell Walls
- The cell wall of gram-positive bacteria is smooth and single layer while that of gram-negative bacteria is the way and double layer
- The gram reaction of gram-positive bacteria is that it retain crystal violet dye and stain blue or purple while gram-negative bacteria accept safranin and stain pink or red
- The thickness of the gram-positive bacteria cell wall is about 20 to 80 nanometres while that of gram-negative bacteria is about 8 to 10 nanometres
- The Peptidoglycan Layer of gram-positive bacteria is thick while that of gram-negative bacteria is thin
- Gram-positive bacteria have teichoic acids while gram-negative bacteria lack teichoic acid
- The gram-positive bacteria lack outer membrane while gram-negative bacteria have an outer membrane
- The gram-negative bacteria has porins while gram-positive bacteria lack
- The mesosome of gram-positive bacteria is more prominent while that of gram-negative bacteria is less prominent
- The morphology structure of gram-positive bacteria is Cocci or spore-forming rods while that of gram-negative bacteria is Non-spore forming rods
- The flagella structure of gram-positive bacteria is 2 rings in the basal body while that of gram-negative bacteria is 4 rings in basal body
- The lipid content of gram-positive bacteria is quite low while that of gram-negative bacteria is quite high
- The gram-negative bacteria has Lipopolysaccharide which is absent in gram-positive bacteria
- Gram-positive bacteria produce exotoxins while gram-negative bacteria produce both Endotoxins or Exotoxins
- Gram-positive bacteria are more susceptible to antibiotics while gram-negative are more resistant to antibiotics
- Examples of gram-negative bacteria are Escherichia and Salmonella while gram-positive bacteria are
Similarities between Gram-Positive and Gram-Negative Bacteria
- Both are bacteria cells
- Both are prokaryotes
- Both lack membrane-bound organelles
- Both have covalently closed circular DNA
- Both contain plasmids
- Both groups possess a capsule
- Both have cell walls
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Comparison Video
Summary
The main difference between gram-negative and gram-positive bacteria is that gram-negative bacteria accept safranin and stain pink or red during gram reaction while gram-positive bacteria retain crystal violet dye and stain blue or purple.