Question Video: Classifying Organisms as Archaebacteria or Eubacteria Biology

Video Transcript

A unicellular organism has been discovered. The organism usually resides in the human gut and requires access to oxygen to survive. Which kingdom, Archaebacteria or Eubacteria, is this organism most likely to belong to?

Did you know that we used to generally divide life into five main kingdoms? These kingdoms were Protista, Fungi, Monera, Plantae, and Animalia. Each kingdom is a taxonomic group that helps classify organisms that have common characteristics.

For this question, we are going to have a closer look at the kingdom Monera. Organisms in this kingdom are unicellular and contain cell walls. They reproduce by an asexual process called binary fission. An important thing to note is that organisms in kingdom Monera do not contain nuclei. Instead, their DNA is found in chromosomal loops and smaller, more specialized loops of DNA called plasmids within the cytosol.

In 1977, Carl Woese proposed to divide the kingdom Monera into two more distinct kingdoms: Archaebacteria and Eubacteria. Let’s take a look at a Venn Diagram to compare the two. Archaebacteria are usually found in extreme environments. These organisms don’t have a substance called peptidoglycan in their cell walls and have noncoding DNA present in their genetic material. Eubacteria are fairly commonplace and can be found in pretty much all environments, including within and on the surface of most multicellular organisms, like humans. Their cell walls are made of peptidoglycan. They have no noncoding DNA, and they show a wide diversity of shapes.

The key piece of information that is given to us in the question about this mystery organism is that it lives in the human gut, which is a nonextreme environment. Knowing this, we can deduce the correct answer to this question. The organism most likely belongs to the kingdom Eubacteria.