TX: Kingdoms and Domains Lesson

Welcome to My Kingdom!

There are 3 domains of life: Bacteria, Archaea, and Eukarya. These domains encompass the six kingdoms: Eubacteria, Archaebacteria, Protista, Plantae, Fungi, Animalia. Take a look at the graphic below that shows the relationship between the 3 Domains and 6 Kingdoms that are currently used/accepted.

Today, scientists do look at organisms' physical features, but mostly they group organisms based on evolutionary classification or phylogeny. Phylogeny is the study of evolutionary relationships among organisms. Scientists construct diagrams called cladograms (a tree-like diagram) that show evolutionary relationships among organisms.

The Tree of Life

See description of diagram Links to an external site.

Why are living organisms grouped this way?

Watch the presentation below for answers.

Notice that, in the tree, the Archaea have more in common with Eukarya [are more closely related to eukaryotes than to the other prokaryote domain], than Bacteria.

Traits

There are three groups with different traits:

• Domain Bacteria: Also known as true bacteria, these are microscopic prokaryotes that have no nucleus surrounding the DNA and no cellular organelles enclosed in membranes. Many of these are pathogens (cause disease). Cyanobacteria (photosynthesizing bacteria) reside in this domain.

• Domain Archaea: Most of these live in extreme environments and are therefore called extremophile. Some do live in moderate environments. 

  • • Types of Extremophiles:

      • Halophiles - live in high salt

      • Thermophile - live in high heat

      • Acidophile - live in low pH

• Domain Eukarya:  All eukaryotes that have true nuclei and membrane - bound organelles

What characteristics are used to organize living organisms into kingdoms?

• cell type: prokaryote (without a nucleus) or eukaryote (cell with a nucleus)
• cell complexity: unicellular (composed of one cell) or multicellular (composed of many cells)
• how they obtain energy: heterotroph (cannot make their own food) or autotroph (can make their own food)
• reproduction: asexual (only one organism is needed to make new organisms), sexual (2 parents create games, which then combine to create a new organism), or binary fission (a type of asexual reproduction where the organism splits into two)

The six kingdom system takes into account the division of the prokaryotes into two domains but also subdivides the Eukarya into separate groups.

The six kingdoms are:

1. Kingdom Eubacteria (same as Domain Bacteria)
2. Kingdom Archaebacteria (same as Domain Archaea)
3. Kingdom Protista
4. Kingdom Fungi
5. Kingdom Plantae
6. Kingdom Animalia

Learn more by watching the presentation below:

Kingdoms and Domains Challenge and Before You Go

Practice Time! Use the knowledge you learned from the lesson to complete the practice activities below.

Answer Key Links to an external site.

Before You Go - You Need To Know

The following key points are from the explore section of the lesson. You must know the following information before moving to the next lesson. This is just a summary of the key points.

1. What are the three domains?
   • Archaea, Bacteria, Eukarya
2. What are the six kingdoms?
   • Eubacteria, Archaeabacteria, Protista, Fungi, Plantae, Animalia
3. Which domain is most closely related to Eukarya?
   • Archaea

IMAGES CREATED BY GAVS (FREEPIK)