Video Transcript
A unicellular organism has been
discovered. The organism is adapted to survive
in hot springs that have very high temperatures and low pH levels. Which kingdom, Archaebacteria or
Eubacteria, is this organism most likely to belong to?
This question describes some of the
characteristics of an unidentified unicellular organism. And then it asks us which of two
kingdoms, Archaebacteria or Eubacteria, is this organism most likely to belong
to. In order to answer this question,
we’ll recall the characteristics of organisms that are classified as archaebacteria
and organisms that are classified as eubacteria. And then we’ll use the information
about the mystery organism to determine which of the two groups it most likely
belongs to.
In order to best organize what we
know about these two kingdoms, I’ve made a Venn diagram. There’s one section for eubacteria,
one section for archaebacteria, and where the two circles overlap represents
information that’s true about both. Organisms that belong to kingdom
Eubacteria as well as organisms that belong to kingdom Archaebacteria can be
described as prokaryotic. Prokaryotic organisms are
unicellular, they’re asexual, and they have cells that do not possess a
membrane-bound nucleus.
The word eubacteria means true
bacteria. These are the bacteria that you’re
likely already familiar with. Eubacteria exist nearly everywhere
on Earth, and they possess a cell wall made of a chemical called peptidoglycan. The word archaebacteria means
ancient bacteria. These organisms got their name
because they were first discovered existing in extreme environments. These environments are similar to
ones that were much more common on Earth a long, long time ago. Another distinguishing
characteristic of archaebacteria is that their cell walls are not made of
peptidoglycan.
We’ve determined the
characteristics of archaebacteria and eubacteria. So, now we need to review the
characteristics of our mystery organism and figure out which kingdom it belongs
to. We’re first told that our organism
is unicellular, but that’s a characteristic of both archaebacteria and
eubacteria. So, being unicellular doesn’t help
us to figure out which of the two kingdoms our organism belongs to.
We are also told that this organism
exists where temperatures are very high and pH is very low. While extremely high temperature
and low pH would kill most eubacteria, archaebacteria are known for existing in
extreme environments. A hot spring is a good example of
an extreme environment. So, we can conclude that the
kingdom that this unicellular organism is most likely to belong to is
Archaebacteria.
