Module 7 Notes
Module 7 Notes Geoscience 115
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This 3 page Class Notes was uploaded by Hannah James on Sunday September 6, 2015. The Class Notes belongs to Geoscience 115 at University of Wisconsin - Madison taught by Philip Brown in Spring 2014. Since its upload, it has received 9 views. For similar materials see Science Behind the News- The World Around Us in Geology at University of Wisconsin - Madison.
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Date Created: 09/06/15
Geosci 115 Module 7 Life in Extreme Environments 0 Mendel founder of modern genetics 0 Leeunhoek first to observe singlecell organisms 0 Scientists have long believed that life could only exist in normal conditions 0 But organisms called extremophiles are organisms that live in harsh conditions 0 Scientists cannot agree how to classify life 0 Biologist Lynn Margulis uses 5 kingdoms I Monera prokaryotes more biodiversity that the rest of life altogether I Protoctista eukaryotic microbes products of bacterial symbiosis bacteria living together and relying on each other 0 Algae ciliates and other microbes that don t fit in other categories I Fungi sporeforming molds yeasts and mushrooms I Plantae maternally retained embryoformers I Animalia animals product of an egg fertilized by swimming cellsperm 0 Taxonomy the grouping of organisms was traditionally done by appearance because it was believed that similar appearances showed similar ancestry 0 But microbes create and issue for this process 0 In the 1970 s Carl Woese employed RNA sequences from ribosomes 0 RNA changes slowly and randomly over millennia I So more variation between organisms means a more remote common ancestor and greater evolutionary distance between them 0 An advantage is that not to analyze organisms scientists only have to extract DNA or RNA not grow the organism which is good because scientists do not know the conditions in which all organisms grewgrow O Woese classified life into three domains I Archaea Ancient prokaryotes I Bacteria More modern prokaryotes I Eucarya All organisms w a nucleus eukaryotes plants fungi animals 0 Recently the first DNA sequences and Archaea bacteria have been coded 0 These showed many characters that hadn t been found before and also reinforced that Archaea bacteria are more closely related to eucarya than bacteria 0 The tree of life is extremely complicated and there s lots of confusion about its organization 0 Some suggest another domain exists others say there needs to be one common ancestor etc 0 The more questions are answered the more questions are raised 0 Thomas Brock first found organisms living in hot temperatures in the 1960 s in Yellowstone National Park I Organisms that live at high temperatures are called thermophilic organisms O Grow best between 45 degrees Celsius 113 F and 80 degrees Celsius 176 F O Hyperthermophiles grow best at temperatures higher than this 0 Only prokaryotes from Bacteria and Archaea have been found at these temp and most thermophiles are from Archaea 0 Life in extreme temperatures because species enjoy having a niche all to themselves I DNA and like molecules are usually heatsensitive it is unclear why those of thermophiles are not 0 Possibly because they have more GC than AT bonds of which GC are stronger because they have triple bonds I They also seem to have slightly different chemical compositions which in proteins and other molecules can make them stronger and more heat resistant 0 It is now suggested that organisms evolved downtemperature and were once more related to thermophiles 0 Scientists have not found the upper limit of temperature for life but some speculate it is between 113 and 150 degrees Celsius Lake Vostok is found miles under the Antarctic ice sheet and it was discovered that life exists there 0 This means that in the similar situation on Jupiter s moon Europa life could exist 0 Psycrophilesz coldloving organisms I Grow best around 15 Celsius 59 F but can t grow over 20 Celsius 68 F can also live in temperatures colder than this 0 Have a large impact on global cycles of elements such as carbon because of their abundance I Most of our earth is deep oceans which are cold Hence the high number of psycrophiles Organisms that live in acid are acidophilic 0 Most normal environments are between pH 5 and pH9 prime is pH 7 0 Acidophiles require a pH of 7 inside their cells but a pH of 5 or lower outside their cells 0 Because they can live in toxic metal and eat damaging chemicals like pyrite acidophiles are often used to clean up manmade environmental disasters such as minerock drainage etc In 1996 a meteorite in Antarctica was discovered to be from Mars and possibly a fossil O Polycyclic aromatic hydrocarbons PAHs organic molecules associated with life on Earth were found in the rock and were more concentrated towards the center of it making contamination from Earth rock less likely Rock also contained carbonate molecules which are associated with life Shapes resembling life were also found 0 However there is still no concrete evidence for life on mars no lifefossils have 00 been recorded on the actual planet 0 Scientists know it is from mars because of the meteorite s oxygen isotopic composition different number of neutrons from regular oxygen 0 In recent years the case for life concerning this rock has weakened dramatically with further examination 0 The fossils of bacteria found were wrong because bacteria can t get that small 0 The PAHs could ve been from an early chemical on Mars as opposed to life 0 Also the amino acids found in the rock were the exact same as those in the ice during the time period that the meteorite landed so they re probably terrestrial