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Download The History of Life
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The History of Life 14.2 The origin of Life The Origin of Life: Early Ideas People saw maggots appear on rotting meat People saw mice appear in food storage Thought that living things sprouted from the non-living The Origin of Life: Early Ideas Spontaneous generation is the idea that non-living material can produce life The Origin of Life: Early Ideas In 1668 Francesco Redi showed that living things did not come from nonliving The Origin of Life: Early Ideas People still believed that life must arise from somewhere – Maybe from some vital force in the air The Origin of Life: Early Ideas In mid-1800s Louis Pasteur showed that living things would not arise from air The Origin of Life Biogenesis – the idea that living things come only from other living things Biogenesis became cornerstone of biology But how did the first life on Earth begin? The Origin of Life: Modern ideas For life on Earth to begin – Molecules that contain carbon form Organic molecules – Then are organized into complex molecules Proteins, carbohydrates, nucleic acids The Origin of Life: Modern ideas 1930s Russian Alexander Oparin said – Heat from lightning on the oceans triggered formation of organic molecules 1953 Americans Miller and Urey – Simulated the conditions of early Earth – Supported Oparin’s hypothesis The Origin of Life: Modern ideas 1950s experiments showed that organic molecules in heated water form complex molecules like proteins, ATP American Sydney Fox showed that amino acid chains can form protocells The Origin of Life: Modern ideas Protocells are large structures with a membrane that carry out life activities like growth and division Protocells evolved to prokaryotes The Origin of Life: Modern ideas The first prokaryotes were – Anaerobic – without oxygen – Heterotrophs – don’t make own food The Origin of Life: Modern ideas Next: Archaebacteria – Prokaryotes that live in harsh environs – Autotrophs – make own food – Chemosynthesis – get energy from inorganic compounds in the environment The Origin of Life: Modern ideas Then: Prokaryotes that get food from photosynthesis Start to make oxygen The Origin of Life: Modern ideas Eukaryotes team up evolve when prokaryotes – Proposed by American Lynn Margulis 1960
