It is exceptionally astonishing to realize that microbes alone possess a total realm in the progressive system of living life forms. They are the ubiquitous life forms of the living scene. We can discover microscopic organisms all over. This property can be owed to the way that microbes have a wide scope of the assortment, and a large number of them are adjusted to make do in outrageous natural conditions. An enormous number of microscopic organisms likewise live on different living beings as parasites. The organisms that belong to this kingdom are usually unicellular and are mostly found in a moist environment.
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Characteristics of Monera
The characteristics of the organisms belonging to this kingdom include: –
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The Monerans are unicellular organisms.
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The cell wall is rigid and made up of peptidoglycan.
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Asexual Reproduction through binary fission.
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They contain 70S ribosomes.
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Flagella serves as the locomotory organ.
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It lacks organelles like mitochondria, lysosomes, plastids, Golgi bodies, endoplasmic reticulum, centrosome, etc.
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These are environmental decomposers and mineralizers.
Bacteria
Bacteria are regarded as microscopic organisms that have the ability to survive in diverse environments. They could be both beneficial as well as harmful in certain ways. They usually have a simple structure without a nucleus and with a few cell organelles. The bacteria are generally surrounded by two protective coverings, mainly the outer cell wall and the inner cell membrane. Some bacteria are also covered with a capsule. A few of the bacteria like mycoplasma do not possess a cell wall.
The short whip-like structures called the pili are the extensions that surround the surface of the bacteria. The long whip-like structures are also present on the surface called flagella. They exhibit both autotrophic and heterotrophic modes of nutrition. Autotrophic bacteria are the ones that derive nutrition from the inorganic substances, and they take in the carbon and hydrogen from the atmospheric carbon dioxide, including H2, H2S, and NH3.
Structure of Bacteria
The important features of the bacterial structure are mentioned below.
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Capsule: A slimy capsule is generally present outside the cell wall of a large number of bacteria. This capsule is composed of polysaccharides and nitrogenous substances like amino acids. This slime layer becomes thick to take the shape of a capsule.
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Cell wall: All the bacterial cells are often covered by a strong, rigid cell wall. The cell wall is present inside the capsule.
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Plasma Membrane: Each bacterial cell contains a plasma membrane. It is situated just internal to the cell wall, and it is a thin, elastic membrane that is differentially or selectively permeable.
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Cytoplasm: The cytoplasm is a complex and aqueous fluid or semi-fluid ground substance that is present in the bacteria.
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Nucleoid: The nucleus is present in the bacteria, and they are surrounded by some typical proteins that are not histone proteins.
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Plasmids: Along with the normal DNA chromosomes, many bacteria also have extrachromosomal genetic elements or DNA. These elements are called plasmids.
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Flagella: These are fine, thread-like, protoplasmic attachments. They extend through the cell wall and the slime layer of the flagellated bacterial cells. They help the bacteria to swim in the liquid medium.
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Pili or Fimbriae: Apart from flagella, some tiny or small hair-like outgrowths are also present on the bacterial cell surface, which are called pili.
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Bacterial Shape
There are several types of bacterial structure, which are described below.
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Bacilli– These are rod-shaped bacteria with or without flagella.
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Cocci– These bacteria are spherical or oval in shape. These can be micrococcus (single), diplococcus (in pairs), tetracoccus (in fours), streptococcus (in chains), and staphylococcus (in clusters like grapes).
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Spirillum– These are spiral or coiled-shaped bacteria. They are rigid due to the spiral structure and bear flagella at one or both ends.
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Vibrios– These are commas or small kidney-shaped bacteria with flagella on one end.
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Classification of Monera
There are three classes of Monera namely: archaebacteria, eubacteria and cyanobacteria.
Archaebacteria
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These are some of the most ancient bacteria that were found in extreme habitats like hot springs, salty areas, and marshy areas.
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The structure of the cell wall is unlike the other bacteria that help them survive in extreme conditions.
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They use the autotrophic mode of nutrition.
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Their nucleotide sequences of tRNA and rRNA are unique
Eubacteria
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They are known as “true bacteria.”
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They have a rigid cell wall as it is made up of peptidoglycans.
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It uses flagella for movement.
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They have pili on their surface that help them to stick on the surface of the host.
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They can be divided into two categories, namely gram-positive and gram-negative.
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Examples of eubacteria include rhizobium and clostridium.
Cyanobacteria
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They are blue-green algae.
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They are photosynthetic in nature.
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They are usually found in the aquatic region.
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They also play a role in fixing atmospheric nitrogen.
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Examples include Anabaena, nostoc, spirulina etc.
To conclude the article we have learned about the features and classification of Monera along with their structure.