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Have you ever imagined things with a movie trailer voice?
You know - that dramatic voice that commands you to listen and be intrigued that shows
up on some movie trailers?
We think it could actually work great for biology.
An example?
Ahem.
In a world…with no oxygen...One little yeast cell...will do...FERMENTATION!
Okay tell me that does not make you want to learn at least a little about fermentation?
If so, we have a video about that, and the yeast (which is a fungus) which can do it!
But you know what would be the BEST topic for an exiting movie trailer?
Archaea.
Because they are probably some of the most exciting unicellular organisms out there.
And many of them can live in extreme environments, too.
By extreme, I mean think harsh but then more harsh.
Areas with extreme temperatures or high salt levels.
Though I should point out Archaea are not the only extremophiles; bacteria can be extremophiles
too.
It’s interesting because when I first started teaching, it was common to call Archaea Archaebacteria.
But that is an outdated term because Archaea aren’t bacteria.
Now they do have some things in common with bacteria.
They’re both unicellular.
They’re both prokaryotes so they have no nucleus, and they also don’t have membrane-bound
organelles.
They both have genetic material and cytoplasm and ribosomes.
Both bacteria and Archaea can be classified as autotrophs or heterotrophs, and they both
do binary fission to reproduce.
Still, Bacteria and Archaea are two completely different domains in the three-domain system.
That’s a pretty big separation.
What makes them different?
In the three domain system, you have the domain Bacteria, the domain Archaea, and then the
domain Eukarya which has all the eukaryotes: plants, animals, fungi, protists.
So let’s look at the differences between Bacteria and Archaea.
Membrane structure is very different.
Remember that all cells have a membrane; it’s really important for homeostasis.
If you take a look at our further reading suggestions, you can also explore how the
chemistry of the cell membrane of the domain Archaea is different: one example is that
Archaea membranes typically contain ether linkages instead of ester linkages.
You would find ester linkages in the membranes of Bacteria and Eukarya.
Some Archaea have a lipid monolayer instead of a bilayer.
Turns out that a monolayer, as well as some other structural differences of Archaea membranes,
can be useful for surviving in extreme environments.
You will also find a unique cell wall in Archaea.
Recall that you will find cell walls in bacteria and you’ll find them in Archaea too.
Archaea cell walls can be very diverse---but they don’t have this large polymer called
peptidoglycan.
You will find peptidoglycan in the cell walls of both gram positive and gram negative bacteria.
While Archaea can also technically be gram positive or gram negative---most Archaea staining
gram negative---Archaea don’t have the peptidoglycan.
Archaea can have pseudopeptidoglycan though which is…a little confusing…but it has
a different chemistry to it.
Like all organisms, Archaea have genetic material.
Now similar to bacteria, Archaea DNA is generally arranged in a circle.
Although while bacteria tend to have one origin of replication, Archaea tend to have several.
When studying the genetics of Archaea, it’s interesting that now scientists find more
similarities between the genetics of Eukarya and Archaea than they do Archaea and Bacteria.
So overall, these were just some comparisons of Archaea with bacteria.
Keep in mind that most Archaea can’t be cultured in the lab.
That’s because there is a lot unknown about what kind of media they need to grow on or
nutrients or environmental controls in order to grow them in the lab.
Although, that’s a common challenge for quite a few types of bacteria too.
Before we go, I want to mention my very favorite Archaea genus.
So I have not been to a volcanic spring.
Yet.
Need to travel more.
But Archaea members of the genus Sulfolobus have.
They can handle temperatures that most organisms can’t---like around 80 degrees Celsius.
Hot.
And that’s not all!
This genus can also handle very acidic conditions.
Substances such as hydrogen sulfide, which is dangerous to most living organisms, does
not deter them.
There’s interest in studying how these Archaea could be used to treat industrial waste and
even convert parts of that industrial waste into something that could be useful.
Well, that’s it for the Amoeba Sisters, and we remind you to stay curious.