Wednesday, March 25, 2009
Fishing in Hot Springs
If you were to go "fishing" (see pg. 70) at Yellowstone National Park hot springs (assuming it was legal), what species might you find- list at least two species examples? What characteristics would those species have? What domain of species would you have found? What are the different types (those that live in hot water, in salt, etc.) and name a specific species of each type. Discuss the conditions of the Earth that would lead to these types of species and their characteristics. How have the conditions of the Earth changed so that other species are born and relate to the theme of evolution. Finally, how have these species helped us discover new information?
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If I were to go "fishing" at Yellowstone National Park hot springs, I would find the hyperthermophiles Sulfolobus and Thermoplasma. Both species are able to live in extreme physical conditions, and are hence called extremeophiles. These species would be in the domain Archaea.
ReplyDeleteDifferent types of extremeophiles include thermophiles (heat-loving), acidophiles (can live in pH lower than 3), alkaliphile (can live in pH higher than 9), and halophiles (salt-loving). Archaebacteria Acidianus brierleyi are acidophiles, Bacillus okhensis are alkaliphiles, and Dunaliella salina are halophiles found in the Dead Sea.
Early earth was a truly a place of extreme conditions. Continuous volcanic eruptions, as well as an atmosphere dense with methane and ammonia created areas of great heat and toxicity. Since there was no ozone layer at that time, ultraviolet light flooded the earth. These extreme conditions fostered the adaptation of bacteria to exist at these extreme states. For example, bacteria in highly salty environments began to expend energy to exclude salt from their cytoplasm to avoid protein aggregation. Thermophiles altered the enzymes they used to ensure that the enzymes do not denature at high temperatures.
With the introduction of oxygen in the atmosphere and the formation of the ozone layer, environmental conditions on earth were maintained with lower concentrations of solutes once high in atmosphere, as well as lower heat. For example, concentrations of methane and ammonia were drastically decreased, and the ozone layer cooled the atmosphere due to the expulsion of UV light. Due to these stark changes, there was an introduction of aerobic organisms that depended on oxygen to survive, as well a new array of diverse organisms that fit the new environment.
The adaptation of these organisms to fit the new environment on earth provide us with key insights on how evolution takes place, and provides us with prime examples that we can explore.
Fishing in a hot springs youi would probably find a lot of bacteria called Thermus aquaticus (that should be italicized) and an archaean called Thermococcus litoralis (also should be italicized). Though Vissagen named two archaea, I think it is important ot recongnize that some bacteria have also evolved to be able to withstand the extreme heat of these hot springs and heat vents. Tom Brock at first categorized all of these organisms as bacteria, but the distinction was later made that some of these were bacteria and some were something entirely different - what we now call archaea. All extremophiles, archaea or bacteriahave modifications at the molecular level to help them survive and thrive in their extreme environment, be it high temperatures, acidic pH levels, or high salinity. For the organisms in the hot springs, the heat would have the greatest impact upon the enzymes of these organisms. The organisms would use enzymes that function optimally at near boiling temperatures. These enzymes would not be denatured by the heat, but rather helped by it - bolder temperatures would change the shape of these enzymes in an unfavorable manner. I'm not sure I understand the prompt when it says "[w]hat are the different types (those that live in hot water, in salt, etc.) and name a specific species of each "type" as there are many categorizations containing these qualities (hot water dwelling, salt water dwelling, etc.) in both bacteria and archaea. The earth used to be a much more chaotic place. High energy/heat due to a thin atmosphere, greater salinity in waters, and more acidic and basic regions of water allmade up this environment. As a result, many organisms were adapted to these conditions, developing traits like the heat-adapted enzymes I mentioned earlier. Now, as the earth cooled down, became more stable, and turned into the world we know today, these organisms became restricted to areas like the hot springs of Yellowstone and the saltier ponds of modern day earth. Populations outside of these areas adapted and developed into the organisms we see around us in "normal" heat, salinity, and pH conditions today. We use DNA polymerase from both T aquaticus and T. literalis (again, both italkicized) in performing PCR, or polymerase chain reactions, a process used to quickly replicate samples of DNA. PCR has made innumerable studies possible, gene therapy to inheritance to synthetic chemical production, including many in evolution (amplifying DNA makes it easier to detect mutations). PCR is also used in recombinant DNA technology and forensics.
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