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Name of the cell
organelle
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Functions
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1. Cell
envelope
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Outer
glycocalyx
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Protects the cells, Helps in
adhesion
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Middle
cell wall
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Gives definite shape
and prevents cell from bursting or collapsing in a hypotonic solution.
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Inner plasma
membrane
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Retains cytoplasm, selectively
permeable barrier, helps in movement of molecules, respiration,
photosynthesis, synthesis of lipids and cell wall constituents. Holds
receptor molecules that help to detect and respond to chemicals in their
surroundings.
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2. Membranous
structures
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Mesosomes
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Involves in cell
wall formation, chromosome replication and distribution of chromosomes to
daughter cells. Involved in secretory processes.
Increases plasma
membrane surface area and enzymatic content.
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Chromatophores
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Found in
photosynthetic bacteria like cyanobacteria and purple bacteria.
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3. Cytoplasm
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Inclusion bodies
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Organic inclusion
(Phosphate granules, cyanophycean granules, glycogen granules, b-hydroxybutyrate granules, sulphur
granules, carboxysomes & gas vacuoles)
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Gas vacuoles occur
in cyanobacteria, purple and green photosynthetic bacteria and a few free
floating aquatic forms (e.g. planktonic forms).
They are permeable
to atmospheric gases but impermeable to water. Helps aquatic bacteria to
float on or near surface water and help in positioning themselves in the
water column for trapping sunlight for photosynthesis or for avoiding intense
sunlight.
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Inorganic inclusion or
metachromatic granules (polyphosphate granules or volutin granules and
sulphur granules).
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Volutin granules: storage reservoir for phosphate.
Sulphur granules: These are stored temporarily by some photosynthetic
bacteria. These granules may be formed when bacteria use H2S as
electron donor during photosynthesis.
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Ribosomes
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Site of protein
synthesis
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4. Nucleoid
(Nuclear body or genophore)
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Genetic material
(DNA) is present
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5. Flagella
(filament + hook + basal body)
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Found in the mobile
bacteria. For locomotion
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6. Pilus
(Bacterial surface appendages)
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For mating process.
During conjugation one of the pili donor cell attaches to recipient cell and
forms a conjugation tube through which partial transfer of DNA takes place.
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7. Fimbriae
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Help to attach to
solid surfaces such as rocks in streams and host tissues. Also responsible
for mutual clinging of cells forming a thin film on the liquid and other
thick aggregates.
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8. Spinae
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Found in some gram
positive bacteria. Help to adjust cells to some environmental conditions such
as salinity, pH, temperature etc.
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