Biology: Classification of Living Organisms

Classification of Living Organisms

• Classification is the process of grouping living organisms based on their shared characteristics and evolutionary relationships.
• The most widely used system of classification is the five-kingdom system, which divides living organisms into:
  1. Monera (bacteria and cyanobacteria)
  2. Protista (protozoa, algae, and fungi-like organisms)
  3. Fungi
  4. Plantae (plants)
  5. Animalia (animals)

Characteristics of Microorganisms

• Microorganisms are living organisms that are too small to be seen with the naked eye.
• They can be found almost everywhere, including in soil, water, air, and the human body.
• Characteristics of microorganisms include:
  • Small size
  • Simple structure
  • Ability to reproduce rapidly
  • Ability to adapt to different environments
  • Can be beneficial or harmful to humans and the environment

Classification of Microorganisms

• Microorganisms can be classified based on their cell structure, metabolism, and other characteristics.
• The three main domains of microorganisms are:
  1. Archaea: ancient microorganisms that thrive in extreme environments (e.g. hot springs, salt lakes)
  2. Bacteria: microorganisms that lack a true nucleus and are typically found in soil, water, and the human body
  3. Eukarya: microorganisms with a true nucleus, including protists, fungi, and some algae
• Microorganisms can also be classified as:
  • Prokaryotes: microorganisms without a true nucleus (bacteria and archaea)
  • Eukaryotes: microorganisms with a true nucleus (protists, fungi, and some algae)

Types of Microorganisms

• Bacteria:
  • Examples: E. coli, Staphylococcus aureus, Bacillus subtilis
  • Can be beneficial (e.g. gut flora) or harmful (e.g. pathogens)
• Viruses:
  • Not considered living cells, but can replicate inside host cells
  • Examples: influenza, HIV, COVID-19
• Fungi:
  • Examples: yeast, mold, mushrooms
  • Can be beneficial (e.g. fermentation) or harmful (e.g. fungal infections)
• Protists:
  • Examples: protozoa, algae, slime molds
  • Can be beneficial (e.g. photosynthesis) or harmful (e.g. parasitic infections)

Classification of Living Organisms

• Classification is the process of grouping living organisms based on shared characteristics and evolutionary relationships
• The five-kingdom system divides living organisms into Monera, Protista, Fungi, Plantae, and Animalia

Characteristics of Microorganisms

• Microorganisms are living organisms too small to be seen with the naked eye
• Found almost everywhere, including soil, water, air, and the human body
• Characteristics include small size, simple structure, rapid reproduction, adaptability, and being beneficial or harmful to humans and the environment

Classification of Microorganisms

• Microorganisms can be classified based on cell structure, metabolism, and other characteristics
• Three main domains: Archaea, Bacteria, and Eukarya
• Archaea: ancient microorganisms thriving in extreme environments
• Bacteria: microorganisms lacking a true nucleus, typically found in soil, water, and the human body
• Eukarya: microorganisms with a true nucleus, including protists, fungi, and some algae
• Microorganisms can also be classified as Prokaryotes (bacteria and archaea) or Eukaryotes (protists, fungi, and some algae)

Types of Microorganisms

Bacteria

• Examples: E.coli, Staphylococcus aureus, Bacillus subtilis
• Can be beneficial (e.g. gut flora) or harmful (e.g. pathogens)

Viruses

• Not considered living cells, but can replicate inside host cells
• Examples: influenza, HIV, COVID-19

Fungi

• Examples: yeast, mold, mushrooms
• Can be beneficial (e.g. fermentation) or harmful (e.g. fungal infections)

Protists

• Examples: protozoa, algae, slime molds
• Can be beneficial (e.g. photosynthesis) or harmful (e.g. parasitic infections)