Similarities and Differences Between Gram’s Positive and Gram’s Negative Bacteria
SIMILARITIES BETWEEN GRAM’S POSITIVE AND GRAM’S NEGATIVE BACTERIA
|SN||Characteristics||Gram's Positive||Gram's Negative|
|As seen under microscope (100X)|
|1||Gram's staining||Retains primary stain (crystal violet) and is seem purple/blue/violet under microscope.||Can be decolorized by destaining solution (alcohol), so takes secondary stain (safranin) and thus is seen pink/red under microscope.|
|2||Cell wall (thickness)||Cell wall is 20-30 nano-meter thick.||Cell wall is 8-12 nano-meter thick.|
|3||Cell wall (structure)||Smooth||Wavy|
|4||Peptidoglycan layer||Consists of 90% of cell-wall and thick (multilayered)|
20 nm thick 2 tetrapeptides of adjacent chains of NAM, NAG are linked by peptide bridges (which contains 5 Glycine)
|Thinner (single layered)
2 tetrapeptides of NAM and NAG are directly linked between D-Alanine and DAG within 2 tetrapeptides.
|5||Teichoic acid||Usually present, 10% of cell-wall.|
Polyribitol/polyglycerol phosphate linked to peptidoglycan.
|6||Lipoteichoic acid||Lipid linked teichoic acid present||None/absent|
|7||Periplasmic space||Small or Not present||Present - contains enzymes for transport, degradation and synthesis.|
|8||Outer membrane||None||Phospholipids with saturated fatty acids.
Embedded porins, lipoproteins, transport proteins.
|9||Lipopolysaccharide||None||Lipid A (endotoxin), core polysaccharide, O antigen|