Bacteria
1. First observed by Leeuwenhoek, term coined by
Ehrenberg.
2. Cell wall contains peptidoglycan made up of N-acetyl
glucosamine and N-acetyl muramic acid.
3. DNA is folded to from a compact structure called
nucleoid without definite nuclear membrane and
nucleolus.
4. Nucleoid is connected to the cell membrane by a Y-
shaped invagination of the cell membrane called
Mesosome which participates in cell division and
secretion.
5. A gelatinous layer called capsule may cover the
entire bacterium.
6. Small, hair like structures called pili or fimbriae may
be present which help in surface attachment and
during conjugation.
7. Long, whip-like filaments called flagella are present
for motility.
8. Extrachromosomal, circular DNA that can replicate
independently called Plasmids are present. They
carry genes for antibiotic resistance ( R-plasmid),
fertility factors ( F-plasmids) and bacterocins ( Col-
plasmids).
9. Ribosomes are of 70S type.
10. Reserve food glycogen. Some forms may have
bacteriochlorophyll.
Features of Cyanobacteria/ Blue-Green Algae
1. They are Gram –ve.
2. Protective mucilage present all over the cell so, also called slime algae.
3. 3-4 layered cell wall containing peptidoglycan.
4. Many cyanobacteria show ‘chromatic adaptation’ where they can change the
pigments with the change in wavelength of light. This is called Gaidukov
phenomenon. E.g. Oscillatoria.
5. Flagella and cilia are absent.
6. Invagination of plasmamembrane called lamellasome is present.
, 7. Thylakoids present with small pigment carrying structures called
phycobilisoomes. They contain phycocyanin and phycoerythrin.
8. Photosynthesis is oxygenic and water is the reducing power.
9. DNA is compact and forms a nucleoid/ genophore.
10. Several gas vacuoles are present which help in buoyancy and refraction of
harmful radiations.
11. Ribosomes are of 70S type.
12. Reserve food is cyanophycean starch.
13. They reproduce vegetatively or asexually. Sexual reproduction is absent.
14. Large, pale-coloured, mucilage-free cells called heterocysts occur in many
filamentous forms which help in N2 fixaton and reproduction.
E.g. Nostoc, Anabaena, Spirulina.
Importance of Cyanobacteria
1. Nostoc and Spirulina are used as food as they are rich in proteins.
2. 3 billion years ago oxygenic photosynthesis resulted in the change of reducing
atmosphere of earth and growth of higher life forms.
3. Many can fix nitrogen like Anabaena, Nostoc, etc.
4. They can prevent soil erosion because the mucilage holds the soil particles.
5. They are used in rice fields to increase nitrogen fertility like Anabaena with
the water fern, Azolla are planted in rice fields.
1. First observed by Leeuwenhoek, term coined by
Ehrenberg.
2. Cell wall contains peptidoglycan made up of N-acetyl
glucosamine and N-acetyl muramic acid.
3. DNA is folded to from a compact structure called
nucleoid without definite nuclear membrane and
nucleolus.
4. Nucleoid is connected to the cell membrane by a Y-
shaped invagination of the cell membrane called
Mesosome which participates in cell division and
secretion.
5. A gelatinous layer called capsule may cover the
entire bacterium.
6. Small, hair like structures called pili or fimbriae may
be present which help in surface attachment and
during conjugation.
7. Long, whip-like filaments called flagella are present
for motility.
8. Extrachromosomal, circular DNA that can replicate
independently called Plasmids are present. They
carry genes for antibiotic resistance ( R-plasmid),
fertility factors ( F-plasmids) and bacterocins ( Col-
plasmids).
9. Ribosomes are of 70S type.
10. Reserve food glycogen. Some forms may have
bacteriochlorophyll.
Features of Cyanobacteria/ Blue-Green Algae
1. They are Gram –ve.
2. Protective mucilage present all over the cell so, also called slime algae.
3. 3-4 layered cell wall containing peptidoglycan.
4. Many cyanobacteria show ‘chromatic adaptation’ where they can change the
pigments with the change in wavelength of light. This is called Gaidukov
phenomenon. E.g. Oscillatoria.
5. Flagella and cilia are absent.
6. Invagination of plasmamembrane called lamellasome is present.
, 7. Thylakoids present with small pigment carrying structures called
phycobilisoomes. They contain phycocyanin and phycoerythrin.
8. Photosynthesis is oxygenic and water is the reducing power.
9. DNA is compact and forms a nucleoid/ genophore.
10. Several gas vacuoles are present which help in buoyancy and refraction of
harmful radiations.
11. Ribosomes are of 70S type.
12. Reserve food is cyanophycean starch.
13. They reproduce vegetatively or asexually. Sexual reproduction is absent.
14. Large, pale-coloured, mucilage-free cells called heterocysts occur in many
filamentous forms which help in N2 fixaton and reproduction.
E.g. Nostoc, Anabaena, Spirulina.
Importance of Cyanobacteria
1. Nostoc and Spirulina are used as food as they are rich in proteins.
2. 3 billion years ago oxygenic photosynthesis resulted in the change of reducing
atmosphere of earth and growth of higher life forms.
3. Many can fix nitrogen like Anabaena, Nostoc, etc.
4. They can prevent soil erosion because the mucilage holds the soil particles.
5. They are used in rice fields to increase nitrogen fertility like Anabaena with
the water fern, Azolla are planted in rice fields.
