Monera Bacteria Archaebacteria Cyanobacteria

Monera Bacteria Archaebacteria Cyanobacteria

 INTRODUCTION: This Chapter Contains Monera Bacteria Archaebacteria Cyanobacteria. Monerans having Archaebacteria and Eubacteria. Eubacteria having Bacteria and Cyanobacteria.

BACTERIA: Bacteria were discovered by Leeuwenhoek in 1676.

• Peptidoglycan cell wall.
• Mucilage covering.
• Ribosomes are the 70s in nature.
• Membrane-covered cell organelles are absent.
• Nutrition is photoautotrophic, chemoautotrophic, saprotrophic.
• Flagella is present.

Image 1: Bacteria

Structure of Bacterial cell:

• Coccus-  Spherical shape
• Bacillus- Straight and cylindrical shape
• Spirillum- coiled like a corkscrew shape
• Vibrio- comma, curved rod, or single turn of spiral shape
• Stalked- stalk-like
• Budding- swollen

Flagellation: Describe on the basis of the presence or absence of flagella.

• Atrichous- Flagella absent
• Monotrichous- Single flagella occurs
• Amphitrichous- flagella is present on two ends
• Cephalotrichous- Group of flagella at one end
• Lophotrichous- Group of flagella at two ends
• Peritrichous- no. of flagella all over the surface

Gram-positive Bacteria	Gram-negative Bacteria
Retain blue and purple colored when washed with absolute alcohol.	Do not retain color when washed with absolute alcohol.
Outer the membrane is absent.	Present
Single layered wall.	Wall is two layered.
Lipid content in the wall is quite low.	20-30% lipid content is present in the wall.
Mucopeptide content is 70-80%.	It is 10-20%.
Porins are absent.	Present
Teichoic acids are present.	Absent

    Table 1: Gram +ve and -ve bacteria

See Also: Algae Rhodophyta Phaeophyta Chlorophyta

Fungi Phycomycetes Ascomycetes Basidiomycetes

Components of Bacterial Cell:

1. Cell Envelope: It consists of 3 components- Glycocalyx, cell wall, and Plasma membrane

• Glycocalyx- Outermost mucilage layer, gives sticky character to cell, protects from phagocytes, protects from virus, etc.
• Cell wall- Rigid solid covering, having polysaccharide, L and D alanine, Lysine, etc. amino acids are present.
• Plasma membrane- It is Selectively permeable, formed by a phospholipid bilayer, it helps in the respiration process and formation of lipids.

2. Cytoplasm: semi-fluid ground substance, a large number of ribosomes are present, ribosome 70S in nature, mesosome present, it contain plasmids.

3. Nucleoid: consist of a single circular DNA and supercoiled with RNA, present freely in cytoplasm, it is the genetic material.

4. Plasmids: Self-replicating, gives unique phenotypic to bacteria, used as a vector in genetic engineering.

5. Inclusion Bodies: non-living structure, Gas vacuole in cyanobacteria which constitute buoyancy regulation mechanism, Inorganic inclusions occur in bacteria like sulphur granules, iron granules, etc., food reserve contains.

6. Flagella: Bacterial flagellum has 3 parts- basal body, hook, and filament.

7. Pili and Fimbriae: pili are longer and thick outgrowths whereas Fimbriae are short and narrow.

•  Plasmid: Extrachromosomal rings of DNA, plasmid carried non-vital genes.
•  Reproduction:  
• A)Vegetative reproduction- Bacterial DNA undergoes replication and during favorable conditions, cells expand and the cytoplasm divides.
• B)Sporulation: produce many spores. Endospore- highly thick-walled, endospore tolerate 100 °C and has no effect on toxic chemicals.
• C)Sexual reproduction: This take place by Genetic recombination by three methods: Transformation, Conjugation, and Transduction.

1)Conjugation: Bacteria have two types of cells, Male (F+) donor and Female (F-) recipient.

a) Sterile Male Method: (F+ × F- → F- becomes F+)

b) Fertile Male Method: (HFr × F- → F- remains F-)

2)Transformation: Taking of DNA  from the living surrounding medium.

3)Transduction: Transfer of gene-mediated by viruses.

• Respiration: The mode of respiration in bacteria can be aerobic and anaerobic.

a) Obligate aerobes- Respire aerobically

b) Facultative anaerobes- Respire aerobically but switch over when oxygen is low

c) Obligate anaerobes- Respire anaerobically

d) Facultative aerobes- Respire anaerobically but respire aerobically when oxygen is present

• Nutrition: The mode of nutrition is autotrophic and heterotrophic.

a) Photoautotrophic bacteria: Bacteriophyll and bacteriopheophytin pigments occur. 

b) Chemoautotrophic bacteria: Manufacture organic compounds from the inorganic raw material.

c) Saprophytic bacteria: Free-living bacteria take the food from the waste product of animals and plants.

d) Symbiotic bacteria: Mutually beneficial e.g., Rhizobium

e) Parasitic bacteria: Obtain food from others for survival.

• Antibiotics: These are produced by micro-organisms to destroy other living. Penicillin discovered by Fleming it is a commercial antibiotic. e.g., Streptomycin, chloramphenicol, tetracyclines, etc.

Image 2: Antibiotics

Economic Importance of Bacteria:

• The number of antibiotics is manufactured by the bacteria.
• Riboflavin vitamin prepared by the bacteria.
• Lactic acids are produced.
• Butyl and methyl alcohol are produced.
• Saprotrophic bacteria help information of manure.
• Azotobacter, Beijerinckia like bacteria help in nitrogen fixation.
• Ammonifying bacteria help information of Ammonia.
• Help in the dairy industry.

ARCHAEBACTERIA:

• Peptidoglycan is absent in the walls
• Protein and non-cellulosic polysaccharides contain.
• Methanogens: They are anaerobic, mode of nutrition is autotrophic, some live as symbionts.
• Halophiles: They are aerobic and chemoheterotrophs, contain mucilage covering, salt-rich.
• Thermoacidophiles: tolerate high temperature, having branch lipid chain.

CYANOBACTERIA:

• Blue-green algae possess photosynthetic activity.
• Chlorophyll a, carotenoid, phycobilins, etc. pigments are present.
• Morphology: unicellular, colonial, or filamentous. Flagella are absent, trichome is present.
• Cell structure: larger cells, peptidoglycan wall, membrane-bound organelles are absent.
• Thylakoids are freely present in the cytoplasm.
• Gas vacuoles are present.
• Thick-walled heterocyst which is impermeable to oxygen and heterocyst also perform nitrogen fixation.
• Multiply by the asexual method.

Conclusion: Monera kingdom is also called Procaryota. The morphological characteristics are very little. Monera also contains mycoplasma and actinomycetes.

This article covered Monera Bacteria Archaebacteria Cyanobacteria in detail.

 

See Also: Biological Classification