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Unformatted text preview: Unit 4: Biodiversity Chapter 26: The Tree of Life How do you prove that something is alive? o Cell(s) must be present; i.e.: a complex, organized assemblage of molecules enclosed within membranes o A living organism must respond to stimuli o All living things take in energy to maintain order and grow. This process is called metabolism . o Development must occur within a cell (or cells) as growth occurs o An organism must be able to reproduce in some fashion to be alive o For an organism to be alive, it must maintain a balance internally; this constant internal process is called homeostasis. o All organisms must possess a genetic system that is based on the replication of DNA, which is passable from parent to child. How did life originate? Where do we (humanity!) come from? (HINT: not the stork ) o Life may have come from another planet when a meteor or cosmetic dust carried a significant amount of complex organic molecules to Earthlife could have occurred on another planet previous to Earth (liquid water under the surface of Jupiter and suggested fossils on Mars!). This hypothesis is called panspermia . o It is also very likely that the first organisms originated on Earth and lived at very high temperatures (such as early extremophiles, perhaps!) Early earth could have contained either large amounts of CO2 and N2, along with H2O. Other say it also contained H2, which bonded with the other elements to form new compounds. o The MillerUrey Experiment: Assembled an environment similar to the environment of early Earth, which excluded gaseous Oxygen, placed it over water, maintained this temperature under 100 degrees Celsius and stimulated lightning by bombarding it with energy in the form of sparks This experiment showed: Carbons found in CH4 bonded to created new molecules. Among these new substances, amino acids could be found; amino acids (which is a simplified protein) are one of the major kinds of molecules of which organisms are made up of. Also, some of the compounds formed are those found in DNA, such as adenine. Thus, early life could have originated on Earth. Taxonomy (aka: good times!) o Carolus Linnaeus came up with the binomial nomenclature (two part names, Genus and Species) we use today! o The Order of Classification Domain (3 Domains) Eukarya, Archaea and Bacteria Kingdom (6 Kingdoms) Archaea, Bacteria, Protista, Animalia, Fungi and Plantae Phylum Class Order Family Genus Species o Anyone remember the saying that goes with this?...
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