What are gram positive bacteria?And distinguish …

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What are gram positive bacteria?And distinguish between gram positive and gram negative bacteria.

Posted by Thiri Vikraman 7 years, 8 months ago

CBSE > Class 11 > Biology

1 answers

Sia ? 4 years, 9 months ago

In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall.

Gram-Positive bacteria	Gram-Negative bacteria
Cell Wall
A single-layered, smooth cell wall	A double-layered, wavy cell-wall
Cell Wall thickness
The thickness of the cell wall is 20 to 80 nanometres	The thickness of the cell wall is 8 to 10 nanometres
Peptidoglycan Layer
It is a thick layer/ also can be multilayered	It is a thin layer/ often single-layered.
Teichoic acids
Presence of teichoic acids	Absence of teichoic acids
Outer membrane
The outer membrane is absent	The outer membrane is present (mostly)
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
Two rings in basal body	Four 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
These bacteria retain the crystal violet colour even after they are washed with acetone or alcohol and appear as purple-coloured when examined under the microscope after gram staining.	These bacteria do not retain the stain colour even after they are washed with acetone or alcohol and appear as pink-coloured when examined under the microscope after gram staining.