Answer :
Gram reaction divides bacteria into
gram positives and gram negatives depending on the color retained
in the staining procedure. However, there are many major and minor
differences between these two group of bacteria apart from
differences in cell wall structure which are responsible for their
gram reactions.
Some of the differences are as
follows :
- Gram positive bacteria have
Teichoic acid in their cell wall whereas it is absent in gram
negative bacteria. Teichoic acids are bacterial copolymers of
glycerol phosphate and carbohydrates that are linked through
phosphodiester bonds. Teichoic acids affect the bindings of
extracellular molecules on bacterial cell and thereby offer
protection to the bacteria.
- Gram Positive bacteria do not have
an outer membrane like gram negative bacteria. Hence, Gram positive
bacteria also do not have porins which are present in the outer
membrane of gram negative bacteria. Porins play an important role
in transport of water molecules and are responsible for making
bacteria resistant to surfactants and detergents.
- Gram positive bacteria primarily
produce Exotoxins whereas Gram negative bacteria can produce
endotoxins as well as exotoxins. The outer layer of gram negative
bacteria itself is a toxin when it enters blood stream of humans or
other animals. Exotoxins are toxins that are secreted out of the
body of the bacteria whereas Endotoxins are available within the
body of the bacteria and are released when bacterial cell is
lysed.
- Gram Positive bacteria are more
sturdy and show greater resistance to physical disruption as
compared to Gram Negative bacteria. This is also a function of
their cell wall.