Kingdom Monera
The work of Carolus Linnaeus and Woese in 1758-1759 and 1990 respectively has been the foundation and influenced the classification system of living things up to the present times. Before you continue with this topic, you should have watched our video lesson on Classification of Living Things.
Objectives of today's topic are:
1. Identify the two domains involved in this kingdom.
2. List ten characteristics of this kingdom.
3. List two major phyla under Eubacteria (Bacteria domain).
4. State eight characteristics of phylum schizophyta.
5. List three common examples of harmful organisms in this kingdom.
6. List three common examples of beneficial organisms in this kingdom.
7. Enumerate ten characteristics of phylum cyanophyta.
8. List three harmful effect of cyanobacteria bloom in aquatic environment.
9. List three common examples of organisms in cyanophyta.
10. What characteristic features differentiate archaebacteria from eubacteria?
Introduction
This kingdom consists of organisms that are classified under two domains: bacteria and archea. They are referred to as eubacteria and archeabacteria respectively.
Characteristics of Kingdom Monera
1. They are unicellular or single cell organisms.
2. They are prokaryotes, they do not have membrane bound organelles.
3. Their cells do not possess endoplasmic reticulum or mitochondria.
4. They reproduce by asexual means mostly by binary fission. Other modes include spore formation and horizontal gene transfer.
5. Archaebacteria may have both sexual and asexual mode of reproduction ranging binary fission, conjugation etc.
6. Some possess chlorophyll and are photosynthetic in their mode of nutrition.
7. Some do not possess chlorophyll and so they are heterotrophic in their mode of nutrition.
8. Some may be motile while most are non-motile (ability to move).
9. Those that are motile have motility organelles such as flagella and cillia.
10. Some may possess cell wall (most bacteria species) and some do not have cell wall.
Note: Eubacteria have two major phyla which are schizophyta and cyanophyta.
Archaebacteria have their separate division.
Phylum Schizophyta: Characteristics
The name of this phylum is obsolete since the creation of domains but this phylum consists majorly the bacteria (eubacteria). Their specific characteristics are:
1. They are prokaryotes, unicellular organisms.
2. They reproduce by binary fission (an asexual mode of reproduction).
3. They possess cell wall containing polysaccharides and amino acids called PEPTIDOGLYCAN.
4. They do not contain chlorophyll and are not photosynthetic.
5. They are mostly motile and possess motility organelles like flagella.
6. Some can cause plant and animal diseases. They are pathogenic e.g Vibrio cholerae (cholera), Clostridium dificile (dysentery), Treponema palidum (syphilis), Neiserria gonorrhoeae (gonorrhea) etc.
7. Some are beneficial or economical e.g Lactobacillus acidophilus (yoghurt, lactic acid production), Streptomyces griseus (antibiotics), Bacillus thuringiensis (biological control of pests).
8. They have different appearances and shapes e.g cocci-round (Streptococcus), bacilli- rod (Bacillus cereus, Escherichia coli), vibrio- curved (Vibrio cholerae), spirochete- spiral (Treponema pallidum).
Phylum Cyanobacteria: Characteristics
This phylum consists of chlorophyll containing bacteria and this include blue-green bacteria and prochlorophyta group. Their specific characteristics are:
1. They can occur in form of filaments or colonies.
2. They possess chlorophyll and are photosynthetic.
3. Other pigments include carotenes, xanthophylls, c-phycoerythrins and c-phycocyanins.
4. Their cells have cell wall.
5. They do not have flagella or cilia.
6. They are motile by means of gliding.
7. They reproduce by binary fission.
8. Some filamentous cyanobacteria have special structures heterocysts which help them fix nitrogen (converting atmospheric nitrogen into chemical form which is utilized by the organisms).
9. They are found in freshwater, marine and terrestrial environment.
10. They are the major oxygen producing bacteria.
Some produce toxic substance which makes them inedible for most herbivores.
11. They cause bad odour, water contamination, creates anoxic environmental for aquatic animals when they grow on water surfaces (bloom).
12. Examples include Nostoc, Anabena, Oscillatoria etc.
ARCHAEBACTERIA
The word "achae" is from the Greek word meaning "ancient". Therefore, they are the oldest living organisms on the planet earth. Their major characteristics are:
characteristics
1. They are unicellular organisms.
2. They are prokaryotes but the genetic examinations (16 sRNA) showed that they are different from bacteria.
3. Many has cell wall but few (Ferroplasma and Thermoplasma) don't have cell wall.
4. Their cell wall lack peptidoglycan.
5. Some achaebacteria have pseudopeptidoglycan (similar to bacteria peptidoglycan but chemically different).
6. Their membrane contains lipids which are glycogen-ether linked.
7. They have plasmids (circular fragments of DNA).
8. Their DNA is circular.
9. Their mode of nutrition can phototrophic, lithotrophic or organotrophic.
10. They are found in extreme environments and so can be classified according to their habitat I.e halophiles or halophilic (salt loving), acidophiles or acidophilic (acid loving), thermophiles or thermophilic (extreme high temperature loving) and methanogens (methane gas producers).
Archaebacteria phyla
Acheabacteria can be divided into twelve phyla namely: Aigarchaeota, Bathyarchaeota, Crenarchaeot,Euryarchaeota, Geoarchaeota, Heimdallarchaeota, Korarchaeota, Lokiarchaeota, Nanoarchaeota, Odinarchaeota, Thaumarchaeota and Thorarchaeota.
Examples of achea include Acidolobus, Halorubium, Desulfurococcus, Sulfolobus etc.
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