Did You Know?
The word Monera is derived from the Greek word 'moneres' that means 'single', which is in reference to the single-celled prokaryotes.
Bacteria are everywhere. They are both good and bad. Some make us healthy while some make us sick. They are capable of turning milk into yogurt or cheese. Decomposition is possible because of them. They help in fighting many diseases. Ever wondered how bacteria could be so useful and significant to us and our lives?
Many centuries ago, organisms were classified according to their complex structure. The five kingdoms of living beings include the eukaryotic Protista, Fungi, Plantae, and Animalia. The single-celled organisms like bacteria were placed under the kingdom Monera. Many scientists consider them to be the oldest forms of life on Earth. After an in-depth study of the characteristics of Monera kingdom, it was divided into two groups archaea and bacteria. This classification of living beings was under the three-domain system of taxonomy that was established in 1991. The third domain included the Eukaryote group. The common names used for Monera sometimes include Prokaryota or Prokaryotae. They are tiny, omnipresent single-celled organisms that are found in almost every corner of this planet.
Characteristics of Monera
The following characteristics will help you get a better understanding of the kingdom of classification.
- Monera are about 1 micrometer in size and complex as living molecules.
- The Monera cell structure is mostly unicellular and some organisms orm groups or filaments.
- These organisms are the simplest prokaryotic cell structures.
- The cell structure lacks nuclei and many other cell organelles.
- They have a cell wall made of polysaccharides with polypeptide cross links with a chemical called peptidoglycan.
- They lack enclosed sub-cellular organelles like mitochondria and only have ribosomes.
- The genetic material DNA is contained in the cytoplasm called nucleoid.
- Many bacterial species contain rings of DNA called plasmids.
- The cytoplasm is enclosed by plasma membrane that lies beneath the cell wall.
- The plasma membrane is made up of lipids and proteins.
- Some Monera have hair like pilli for adhesion or tail-like flagella for locomotion.
- The source of nutrition for these organisms is usually photosynthesis or chemosynthesis.
- The characteristics also include the shape of the cell that includes round (cocci), rod-like (bacilli), or spiral (spirochetes or spirilla).
- Reproduction is asexually through binary fission or sexually by conjugation. The process of circulation and digestion is carried out through diffusion.
- The Monera kingdom includes all bacteria that may infect animals, humans, and plants. But most of the members are termed as beneficial bacteria, rather than pathogenic bacteria.
- The Monera kill organisms causing pathogenic diseases, breaks down algae, and can even recycle chemical pollutants like hydrogen sulfide and ammonia.
- Bacteria that grow in the root nodules help break down atmospheric nitrogen into fixed nitrogen.
- The bacteria that forms the natural flora of the intestines are very important for proper digestion.
- One of their many characteristics also includes production of antibiotics likes streptomycin that is useful for treatment of infections.
- Monera can be identified by their characteristic of cell wall that can be or not stained by Gram staining.
- Most of the Moneora can survive harsh environment by producing spore coat.
Division of Kingdom Monera
The kingdom Monera is divided into many sub kingdoms as well as phyla. These sub kingdoms and phyla include:
- Sub-kingdom Archaebacteria: Their characteristics includes survival in harsh conditions intolerable to other organisms.
- Sub-Kingdom Eubacteria: This kingdom includes all bacteria known as 'true bacteria' except archaebacteria.
- Phylum Anaerobic Phototrophic Bacteria: Their characteristics includes photosynthesis that does not use water as the initial substrate and does not produce oxygen as end product.
- Phylum Cyanobacteria: These Monera are blue-green bacteria that carry out photosynthesis with help of chlorophyll A and blue pigment phycocyanin.
- Phylum Prochlorophyta: These are organisms that contain chlorophyll A and B.
- Phylum Schizophyta: These Monera include heterotrophic eubacteria that include different types of bacteria like saprobes and parasites.
Examples of Monera