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History of Life on Earth. January 12, 2009. What is the age of the Earth?. 4,500 years old 4,500,000 years old 4,500,000,000 years old 4,500,000,000,000 years old. Miller-Urey Experiment. Showed that, under certain conditions, organic compounds could form from inorganic molecules
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History of Life on Earth January 12, 2009
What is the age of the Earth? • 4,500 years old • 4,500,000 years old • 4,500,000,000 years old • 4,500,000,000,000 years old
Miller-Urey Experiment Showed that, under certain conditions, organic compounds could form from inorganic molecules The experiment
Life’s Building Blocks • Hydrothermal Vents: energy from the vents could have fueled chemical reactions and the depth of the sea would have offered protection from solar radiation • Space: some meteorites that have hit the Earth’s surface contain amino acids
Really, Mrs. G? Space?? http://www.nmnh.si.edu/rtp/students/2007/schedule07_mineral_tour_photo_meteorites.html
What process is used to estimate the age of fossil within strata, or layers of the Earth? • half-life • radioactive decay • radiometric dating • relative dating Copralite = Dinosaur dung http://i.livescience.com/images/ig25_dinosaur_dung_09.jpg
What has shaped the geologic time scale of the Earth? • earthquakes • the formation of the Earth • floods • mass extinctions
What do some scientists think provided the energy for chemical reactions that produced the first biological molecules? • meteors • heat from hydrothermal vents • ribozymes • microspheres
The First Cells • Lipids make up cell membranes • Lipids do not mix with water • In water, lipids can form tiny spheres called microspheres. • Microspheres may have been the first step towards cellular organization
Endosymbiosis • A mutually beneficial relationship in which one organism lives within another • Larger cells engulfed smaller cells, which then began to live inside larger cells
Evidence for Endosymbiosis • Size and structure: mitochondria are the same size as most bacteria • Genetic material: both chloroplast and mitochondria contain their own DNA that is different from the DNA of their host cells • Ribosomes: both have ribosomes • Reproduction: Like bacteria, chloroplasts and mitochondria reproduce by simple fission
Which were the first animals to evolve and successfully live on land? • arthropods • reptiles • amphibians • mycorrhizae