Monera Kingdom PDF

General Biology Bio101 Kingdom of Monera Lab 8 Kingdom of Monera The kingdom of Monera includes organisms that are single-celled known as bacteria. The kingdom is divided into two groups Archaebacteria and Eubacteria. All organisms of this kingdom are considered as prokaryotes. Classification King...

General Biology Bio101 Kingdom of Monera Lab 8 Kingdom of Monera The kingdom of Monera includes organisms that are single-celled known as bacteria. The kingdom is divided into two groups Archaebacteria and Eubacteria. All organisms of this kingdom are considered as prokaryotes. Classification Kingdom of Monera has been classified into two groups - Archabacteria and Eubacteria. 1) Archaebacteria are microbes that live in extreme and harsh conditions, they are known as extremophiles. These bacteria lack of cell wall, their cell membrane is made up of different lipids, and their ribosomes are similar to that of eukaryotes. Archaebacteria are of three major groups of bacteria based on their habitat i.e., thermophiles, halophiles and methanogens. t a) Halophiles are bacteria that live in extremely salt water. b) Thermoacidophiles are bacteria are both thermophilic and acidophilic. They can survive and proliferate under extreme high temperatures and low pH. c) Some bacteria are present in the guts of ruminants and are responsible for production of methane gas from their dung (Methanogens). 2) Eubacteria are true bacteria. The characteristic feature is the presence of rigid cell wall and if present a motile flagellum that aids in locomotion. These organisms are characterized based on their nutrition and their shapes. I. Classification Based on Shape Bacteria can be classified in three groups based on shape: 1) Spherical or round shaped bacteria are called cocci, 2) Rod-shaped are bacilli, and 3) spiral shaped bacteria are spirilla. II. Classification Based on Mode of Nutrition Based on mode of nutrition, bacteria are broadly classified into 1) Autotrophic and 2) Heterotrophic. 1) Autotrophic bacteria - Bacteria which prepare their own food are autotrophic. (Example Cyanobacteria) Autotrophic bacteria can be Chemosynthetic or Photosynthetic. Chemosynthetic bateria are those which prepare their food with the help of inorganic substrates. Photosynthetic bacteria are autotrophic bacteria which prepare their own food by the process of photosynthesis. Cyanobacteria (Blue-green algae) - They have chlorophyll similar to plants and hence they are photosynthetic autotrophs. They are marine and terrestrial and they may be unicellular, colonial or filamentous. The colonies are urrounded by gelatinous sheath. They can also fix atmospheric nitrogen. Example: Nostoc and Anaebena. Chemosynthetic autotrophs - these organisms oxidise substances like nitrites, nitrates, ammonia etc. The help in recycling substances like nitrogen, sulphur, iron etc. 2) Heterotrophic bacteria - Bacteria which are dependent on other organisms for their food are heterotrophic.(Example Escherichia coli) Heterotrophic bacteria are those which are dependent on other organism either directly or indirectly for their nutrition. They are most abundant and are important decomposers. Some are helpful in curdling milk, production of antibiotics, in nitrogen fixation and some are pathogens. Heterotrophic bacteria can be parasitic and saprophytic. Parasitic bacteria are those which depend on the host for nutrition and cause harm to the host. Saprophytic bacteria feed on dead and decaying matter. Symbiotic - it is a type where the bacteria are in mutual relation with other organisms. Symbiosis types are: a) mutualism and b) commensalism. Mutualism is where the bacteria and the other organism are benefited due to the relationship. Commensalism is a relationship where the bacteria are benefited while the other organism is not affected by the relationship. III. Classification based on Gram's staining Gram's staining is a test on cell walls developed by Hans Christian Gram. This method uses a combination of dyes to distinguish bacteria with either Gram positive or Gram-negative cell wall. Following the staining, bacteria with Gram positive cell wall appear VIOLET under the light microscope whereas those with Gram negative cell wall structure appear RED. Gram’s stain test; It is a tool for identifying bacteria, based on differences in their cell walls. So how does Gram’s staining work? Gram positive and Gram negative cells differ in the makeup of their cell wall. A)Gram-positive (Gram +ve) bacteria: Their cell walls have large amounts of peptidoglycans that react with Gram’s stain and appear violet under a microscope. B) Gram-negative (Gram -ve) bacteria: Their cell walls have no or small amount of peptidoglycan. So, they do not react or very weakly react with Gram’s stain. They appear red under a microscope. Reproduction in Bacteria 1)Asexual reproduction in bacteria is mainly by “Binary Fission”. Under unfavourable conditions they reproduce by spores. It is the simplest type of asexual reproduction. 2) Sexually bacteria reproduce by a primitive mode of DNA transfer from one bacterium to another i.e., by (a)conjugation, (b)transduction or (c)transformation. Binary Fission: Mechanism of Bacterial Gene Transfer (Sexual reproduction):