Overview of Key Features and Differences Between Organisms

Introduction

• The focus is on the differences between animals, plants, fungi, protists (protocists), bacteria, and viruses.
• Viruses are not considered living organisms and are not in the five kingdoms of life.
• The five kingdoms of life: Animals, Plants, Fungi, Protists, and Bacteria.
• Eukaryotic vs. Prokaryotic:
  • Animals, Plants, Fungi, and Protists are eukaryotes (have eukaryotic cells).
  • Bacteria are prokaryotes (do not have a nucleus).
  • Viruses are not classified as either.

Animals

• Estimated 5-10 million species.
• Characteristics:
  • Multicellular.
  • Heterotrophs (get energy from other organisms).
  • Most reproduce sexually.

Plants

• Approximately 300,000 species.
• Characteristics:
  • Multicellular.
  • Autotrophs (get energy from the sun through photosynthesis).

Fungi

• Characteristics:
  • Some are multicellular, like mushrooms and molds.
  • Some are unicellular, like yeast.
  • Heterotrophs, often referred to as saprotrophs.
  • Use saprotrophic nutrition (external digestion).
  • Multicellular fungi have mycelium made of hyphae.
  • Some fungi can be pathogens (e.g., cause athlete's foot).

Protists (Protocists)

• Terms: Protists, Protista, Protocists, and Protozoa are interchangeable.
• Characteristics:
  • Mostly unicellular.
  • Diverse species, some photosynthesize, others consume organisms.
  • Some can be pathogens (e.g., Plasmodium causes malaria).

Bacteria

• Single-celled organisms found everywhere.
• Characteristics:
  • Some photosynthesize, but lack chloroplasts.
  • Many feed off other organisms, living or dead.
  • More species than all other kingdoms combined.
  • Some are helpful (e.g., aiding digestion), others are pathogens.

Viruses

• Super tiny particles, not cells or living organisms.
• Characteristics:
  • Structure: Protein coat surrounding DNA or RNA.
  • Reproduce only inside living cells (parasites).
  • All viruses are pathogens.
  • Examples: Influenza virus, Tobacco mosaic virus, HIV, COVID-19.

Conclusion

• Understanding the differences between these groups provides a general sense of their nature.
• Encouragement to further explore and understand individual characteristics of each group.