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ORIGINS OF LIFE ON EARTH Alex Bariahtaris The First Cells on Earth Cells can only form from other cells Pasteur experiment Claims of first cells 3.8 billion years ago Bacterial Rocks fossils date from 1.9 billion years in Greenland indicate presence of oxygen (3.8 billion years ago) Requirements of Life on Earth Even prokaryotic cells are intricate Four essential processes for formation of life Chemical reactions>> organic molecules Organic molecules>> polymers Ability of polymers to self-replicate Development of membranes Only way to produce cell-like structures Miller and Urey Experiment Attempted to prove spontaneous formation of life Created conditions that were similar to those believed to exist pre-life Electrical discharges/boiling and condensing water Organic compounds, amino acids formed http://www.mhhe.com/cgibin/netquiz_get.pl?qfooter=/usr/we b/home/mhhe/biosci/genbio/mader biology7/student/olc/art_quizzes/0 049fq.htm&test=/usr/web/home/mh he/biosci/genbio/maderbiology7/st udent/olc/art_quizzes/0049q.txt&a nswers=/usr/web/home/mhhe/biosci /genbio/maderbiology7/student/olc /art_quizzes/0049a.txt Prokaryotes and Eukaryotes Membranes needed to form cells Phospholipids naturally group together, form layers Process forms membrane bound structures known as protobionts Endosymbiotic theory: mitochondria and chloroplasts evolved from prokaryotes Both structures grow, divide like cells, genetic structure http://www.ib.bioninja.c om.au/options/optiond-evolution-2/d1origins-of-life-onearth.html Species/Speciation Separate, unique population capable of interbreeding Controversy: sibling species, asexual repro Formation of a new species, isolation of gene pool Allopatric (geographic separation) and Sympatric (no interbreeding) Evolutionary Trends Adaptive radiation: organisms find different roles Different advantage for different organisms Divergent/Convergent Evolution Divergent, species evolve very differently Convergent species show striking similarities Punctuated equilibrium rate of evolution Consistent with environmental conditions http://www.rocklin.k12.ca.us/staff/ pmorrison/Biology/2007BioAgend as2ndSemester/BioAgenda3-3108.htm Human Origin and Evolution Humans classified as primates, similar anatomical features Grasping limbs, mobile arms, upright posture, etc. Homo sapiens are only existing hominid Fossils have shown evolutionary trends Increasing brain size in relation to body Classification/Phylogeny Arranging organisms into groups is advantageous Species Identification Predictive Value (other species in similar groups) Evolutionary links (similar ancestors) Also artificial classification, based off of one specific characteristic Phylogeny compares structures of proteins and other biochemicals Citations Allott, Andrew. Biology For The IB Diploma: Standard and Higher Level. Oxford: Oxford UP, 2007, Print.
