Table of contents | |
Introduction | |
Classification of Bacteria on the basis of Shape | |
Classification of Kingdom Monera | |
Archaebacteria | |
Eubacteria |
Bacteria are the only members of the Kingdom Monera and are the most abundant microorganisms on Earth. They can be found almost everywhere, with hundreds of bacteria present in just a handful of soil. Bacteria also survive in extreme environments such as hot springs, deserts, icy regions, and the deep ocean, where few other life forms can survive. Many bacteria live as parasites on or inside other organisms.
Bacteria are tiny, single-celled organisms that come in different shapes and sizes. Scientists group bacteria into four categories based on their shape.
Bacterial Structure and Behaviour: Bacteria have a simple structure but exhibit complex behavior and they show the most extensive metabolic diversity compared to many other organisms.
Modes of Nutrition in Bacteria
(a) Autotrophic Bacteria: These bacteria synthesize their own food from inorganic substances.
(b) Photosynthetic Autotrophic: These bacteria use light energy to synthesize food.
(c) Chemosynthetic Autotrophic: These bacteria obtain energy by oxidizing inorganic substances.
(d) Heterotrophic Bacteria: The vast majority of bacteria fall into this category. Heterotrophic bacteria depend on other organisms or dead organic matter for food.
Now that you've understood Bacteria. It's time to understand how they are classified on the basis of their behaviour. Kingdom Monera is classified into two sub-kingdoms:
In Archaebacteria we will see the examples: Methanogens, Halophiles and Thermoacidophiles. In Eubacteria we will study Cyanobacteria, Chemosynthetic Bacteria, Heterotrophic Bacteria and Mycoplasma.
Archaebacteria are unique bacteria that thrive in extremely harsh environments. They can be found in places like:
(i) Super salty areas(halophiles)
(ii) Hot springs (thermoacidophiles)
(iii) Marshy regions (methanogens).
Do you know: What makes archaebacteria different from other bacteria is their unique cell wall structure, which helps them survive in these tough conditions.
Methanogens, a type of archaebacteria, are found in the guts of animals like cows and buffaloes. They play a crucial role in producing methane (biogas) from the dung of these animals.
There are thousands of different eubacteria, also known as "true bacteria." Eubacteria are characterized by the presence of a rigid cell wall, and if they are motile (capable of movement), they have a flagellum.
(a) Chemosynthetic autotrophic bacteria oxidize various inorganic substances such as nitrates, nitrites, and ammonia, using the released energy to produce ATP (adenosine triphosphate), which is a form of energy used by cells. Chemosynthetic bacteria play a crucial role in recycling nutrients like nitrogen, phosphorus, iron, and sulphur.
(b) Heterotrophic bacteria are the most common type of bacteria found in nature and many of these bacteria play a crucial role as decomposers, breaking down organic matter and recycling nutrients back into the ecosystem.
Some heterotrophic bacteria have a significant impact on human activities. For example, they are involved in:
Note: Bacteria can cause diseases in humans, plants, and animals. For example, diseases like cholera, typhoid, tetanus, and citrus canker are caused by different types of bacteria.
Mycoplasma are unique organisms that do not have a cell wall. They are the smallest known living cells and can live without oxygen. Some mycoplasma species can cause diseases in animals and plants.
Mycoplasma
Bacteria are mainly reproduced by a process called fission. However, in harsh conditions, they can produce spores. They can also exchange genetic material through a primitive form of sexual reproduction.
A Dividing Bacterium
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1. What are the main shapes of bacteria, and how are they classified based on shape? |
2. What is the difference between Archaebacteria and Eubacteria? |
3. What are some examples of Archaebacteria and their habitats? |
4. How do Eubacteria benefit humans and the environment? |
5. What are some characteristics used to classify bacteria within the Kingdom Monera? |
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