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.