Bacteria and Archaea
BACTERIA AND ARCHAEA are both prokaryotic single-celled organisms.
Many of the bacteria and archaea species discovered were found to be extremophiles that thrived in harsh conditions that would have killed your average life form. Some were found to grow best at temperatures above the boiling point of water or in toxic, acidic waste. Others were found to live completely independent of sunlight and oxygen, feasting on sulfur bubbling up from deep sea vents..
Bacteria and Archaea have genetic adaptations that enable them to survive and even thrive in these extreme environmental conditions. In fact, these tolerances to extreme conditions was required! The first prokaryotic organisms existed at least 3.5 billion years ago, when the Earth was a much hotter and more extreme place than it is now.
It was this knowledge that lead Carl Woses to name his newly discovered prokaryotic organisms (in the 1970's) as the archaebacteria. The prefix, "archae" means "ancient". However, as more species of both bacteria and archaea continued (and continue) to be discovered, the term was changed to more simply "archaea". This was to better reflect the fact that
- Not all prokaryotic organisms are extremophiles
- Not all prokaryotic organisms are related the known "ancient ancestors"
- The Archaea should be clearly distinguished from Bacteria
You may recall, that prokaryotic cells do not have a nucleus and they do not contain any membrane-bound organelles.
Even though all of the organisms that make up the Bacteria and Archaea Domains are Prokaryotic, There Are A LOT of Differences !
One difference, is that there are no known species of archaea that are pathogenic to humans. On the other hand, we know plenty of bacteria that can make humans ill.
A tour of Bacteria
Bacteria can be found almost anywhere!
Bacteria are extremely diverse and have been found in some of the most inhospitable places to live on Earth. This includes...
- In the air and clouds
- In the soil (even deep underground)
- In water (including deep sea)
- In glacial ice
- In radioactive waste
- In thermal and acidic hot springs and vents