Extremophiles Readings : 1) Wikipedia links: “Extremophile” and “Panspermia” 2) Life on the edge: Adventures of an extremophilic scientist: Darlene Lim 3) Madigan & Marrs, Extremophiles. Scientific American, April 1997 Definitions Types Clues to the origin of life
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Extremophiles - Department of Biological Sciences, Studies in Life
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Extremophiles
Readings:
1) Wikipedia links: “Extremophile” and “Panspermia”2) Life on the edge: Adventures of an extremophilic scientist: Darlene Lim3) Madigan & Marrs, Extremophiles. Scientific American, April 1997
DefinitionsTypesClues to the origin of life
What are “extremophiles” and where do you find them?”
“There are many different classes of extremophiles, each corresponding to the way its environmental niche differs from mesophilic conditions. These classifications are not exclusive. Many extremophiles fall under multiple categories. For example, organisms living inside hot rocks deep under Earth's surface are both thermophilic and barophilic.”
An “Extremophile” can be any organism found in extreme environments (not just archaebacteria)
Tardigrades (Phylum Tardigrada) are microscopic animals (>1000 spp.) that are found from the Himalayas to the deep seas, and from the
equator to the poles.
Tardigrades are polyextremophiles and are able to survive in extreme environments that would kill almost any other animal. Some can survive temperatures of -273°C, close to absolute zero, temperatures as high as 151 °C (303 °F), 1,000 times more radiation than other animals such as humans, almost a decade without water , and even the vacuum of space. In September 2007, tardigrades were taken into low Earth orbit on the FOTON-M3 mission and for 10 days were exposed to the vacuum of space. After they were returned to Earth, it was discovered that many of them survived and laid eggs that hatched normally, making these the only animals shown to be able to survive the vacuum of space. http://en.wikipedia.org/wiki/Tardigrade
3.5 BYA – Possible fossil bacteria with organic inclusions
3.2 BYA – Filamentous microfossils
3.0 – 2.7 BYA – Developed bacterial communities (photosynthetic stromatolites)
Raven & Johnson 1992
Earth’s Early Life Forms
Campbell & Reece 2002
Raven & Johnson 1992
“Biological Clock”
˜3.5BYA
˜3.8BYA
˜4.6 BYA
Theories regarding life’s origins:
“Primordial soup” (Miller and Urey’s experiments)
“Panspermia” – “seeding” of organic compounds or organisms from space (analysis of organic molecules in meteorites)
Evidence regarding the early Earth and life’s origins
Early conditions (first 800 MY) were hostile to “life as we know it”bombardment from outer space (accretion)extremely hotvolcanic activity – release SO2no atmosphere
Later conditionsearly atmosphere – lots of CO2, no O2, O3bombardment from outer space
Campbell & Reece 2002
Raven & Johnson 1992
Earth’s Early Energy Sources
The early Earth was a harsh environment, unsuitable for most modern-day organisms (except certain extremophiles?)
The Miller and Urey Experiment (1953) – organic molecules can be made from inorganic ones under the right conditions (believed to resemble the early Earth).
Raven & Johnson 1992
Life abounds in the stranges places…thermal hot springs
Campbell & Reece 2002
… deep sea vents
Campbell & Reece 2002
Theories regarding life’s origins:
“Primordial soup” (Miller and Urey’s experiments)
“Panspermia” – “seeding” of organic compounds or organisms from space (analysis of organic molecules in meteorites)
http://en.wikipedia.org/wiki/Panspermia
Panspermia Hypothesis – the “seeds” of life exist throughout the universe (perhaps as extremophiles!). The Earth was “seeded” by life arriving from space (also called “Exogenesis”).