CYTOPLASMIC INCLUSIONS OF BACTERIA
The cytoplasm is a homogenous aqueous solution enclosed by plasma membrane.
It contains all the cell organelles and also soluble proteins, metabolites, enzymes,
amino acids, etc.
Other important cytoplasmic components of prokaryotes include the following:
RIBOSOMES
They are composed of rRNA and proteins, with diameter 10-20nm.They have 80-85%
of bacterial RNA.
They are sometimes found as polysomes. Polysomes are group of ribosomes formed
when many ribosomes translate a single mRNA.
Sedimentation coefficient of prokaryotic ribosome is 70S with 50S and 30S being the
sedimentation coefficients of large and small subunits respectively. Each subunit has
almost equal amounts of rRNA and protein.
The ribosome is functional only when the two subunits are together. The association
and dissociation of the two subunits depend on Mg+2 ion concentration. At 0.001M
concentration of Mg+2 , the ribosome is stable.
The 50S subunit consists of 23S rRNA , 5S rRNA and 34 different proteins designated
as L1 to L34.
The 30S subunit consists of 16S rRNA and 21 different proteins designated as S1 to
S21 .
They are the sites of protein synthesis. Antibiotics like Streptomycin and
Chloramphenicol inhibit protein synthesis in bacteria by attacking its ribosomes.
The number of ribosomes in bacteria are less, in 100s. But the number greatly
increases up to 15,000-20,000 per cell during protein synthesis.
VOLUTIN GRANULES
Also called Polyphosphate or Metachromatin granules.
They are composed of poly metaphosphate.
Many diptheria bacilli and lactic acid bacteria have them.
They are easily observed under light microscope due to their highly refractile nature.
Under electron microscope, they appear as round, dark areas.
These granules stain reddish with blue dyes such as Methylene blue.
Volutin granules act as intracellular phosphate reserve when nucleic acid synthesis
does not occur. When nucleic acid synthesis starts, this phosphate gets incorporated
into the nucleic acid.
POLY BETA HYDROXYBUTYRATE (PHB) GRANULES
1
The cytoplasm is a homogenous aqueous solution enclosed by plasma membrane.
It contains all the cell organelles and also soluble proteins, metabolites, enzymes,
amino acids, etc.
Other important cytoplasmic components of prokaryotes include the following:
RIBOSOMES
They are composed of rRNA and proteins, with diameter 10-20nm.They have 80-85%
of bacterial RNA.
They are sometimes found as polysomes. Polysomes are group of ribosomes formed
when many ribosomes translate a single mRNA.
Sedimentation coefficient of prokaryotic ribosome is 70S with 50S and 30S being the
sedimentation coefficients of large and small subunits respectively. Each subunit has
almost equal amounts of rRNA and protein.
The ribosome is functional only when the two subunits are together. The association
and dissociation of the two subunits depend on Mg+2 ion concentration. At 0.001M
concentration of Mg+2 , the ribosome is stable.
The 50S subunit consists of 23S rRNA , 5S rRNA and 34 different proteins designated
as L1 to L34.
The 30S subunit consists of 16S rRNA and 21 different proteins designated as S1 to
S21 .
They are the sites of protein synthesis. Antibiotics like Streptomycin and
Chloramphenicol inhibit protein synthesis in bacteria by attacking its ribosomes.
The number of ribosomes in bacteria are less, in 100s. But the number greatly
increases up to 15,000-20,000 per cell during protein synthesis.
VOLUTIN GRANULES
Also called Polyphosphate or Metachromatin granules.
They are composed of poly metaphosphate.
Many diptheria bacilli and lactic acid bacteria have them.
They are easily observed under light microscope due to their highly refractile nature.
Under electron microscope, they appear as round, dark areas.
These granules stain reddish with blue dyes such as Methylene blue.
Volutin granules act as intracellular phosphate reserve when nucleic acid synthesis
does not occur. When nucleic acid synthesis starts, this phosphate gets incorporated
into the nucleic acid.
POLY BETA HYDROXYBUTYRATE (PHB) GRANULES
1
