Origin of Life 15.8 Power Point (1).ppt - Origin of Life 15.8 copyright cmassengale 1 Aristotle(384 –322 BC Proposed the theory of spontaneous

Origin of Life 15.8 Power Point (1).ppt - Origin of Life...

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Unformatted text preview: Origin of Life 15.8 copyright cmassengale 1 Aristotle (384 –322 BC) Proposed the theory of spontaneous generation Also called abiogenesis Which is the idea that living things can arise from nonliving matter This idea lasted almost 2000 years. copyright cmassengale 2 copyright cmassengale 3 Spontaneous Generation For centuries, people based their beliefs on their interpretations of what they saw going on in the world around them without testing their ideas. They didn’t use the scientific method to arrive at answers to their questions. Their conclusions were based on untested observations copyright cmassengale 4 Examples of Spontaneous Generation copyright cmassengale 5 Example #1 Conclusion: It was perfectly obvious to people back then that muddy soil gave rise to the frogs copyright cmassengale 6 Example #2 Conclusion: It was obvious to them that the mice came from the moldy grain. copyright cmassengale 7 Example #3 Conclusion: Obviously, all the sewage and garbage turned into the rats. copyright cmassengale 8 Example #4 Conclusion: the rotting meat that had been hanging in the sun all day was the source of the flies. copyright cmassengale 9 Disproving Spontaneous Generation copyright cmassengale 10 Francesco Redi (1668) In 1668, Francesco Redi, an Italian scientist, did an experiment with flies and wide-mouth jars containing meat copyright cmassengale 11 Redi’s (1626-1697) Experiments Experiment Results: (evidence against spontaneous generation) 1. Unsealed – had maggots and flies on meat 2. Sealed – had no maggots or flies on meat 3. Gauze – had a few maggots on meat copyright cmassengale 12 Francesco Redi copyright cmassengale 13 Disproving Spontaneous Generation of Microbes copyright cmassengale 14 Anton van Leeuwenhoek (1674) Leeuwenhoek began making and looking through simple microscopes He examined water and visualized tiny animals (fungi, algae, and single celled protozoa) and called them “animalcules” By end of 19th century, these organisms were called microbes copyright cmassengale 15 1723 copyright cmassengale 16 Leeuwenhoek’s Microscope copyright cmassengale 17 Louis Pasteur (1822-1895) copyright cmassengale 18 Pasteur's Problem Hypothesis: Microbes come from cells of organisms on dust particles in the air Pasteur put broth into several special S-shaped flasks Each flask was boiled and placed at various locations in the room. copyright cmassengale 19 1 S-shaped Flask Filled with broth The special shaped flask was intended to trap any dust particles containing bacteria copyright cmassengale 20 3 Flask left at various locations in the room. Did not turn cloudy Microbes not found Notice the dust that collected in the neck of the flask copyright cmassengale 21 Results copyright cmassengale 22 The Theory of Biogenesis Pasteur’s S-shaped flask kept microbes out but let air in. Proved microbes only come from other microbes (life from life) - biogenesis copyright cmassengale Figure 1.3 23 Other Theories of Life • Alexander Oparin – Russia 1930’s – Life began in the oceans when the Sun, lightening, and the Earth’s heat triggered the formation of molecules that were washed into the sea creating the Primordial Soup Theory – This Primordial Soup contained organic molecules like lipids, carbohydrates, and amino acids. • Miller and Urey – 1953 – USA – Tested Oparin’s theory in the lab and found that they could “make” amino acids, sugars, and organic compounds by mimicking the conditions of early Earth. Section 2 The History of Life The Origin of Life Stanley Miller and Harold Urey were the first scientists to show that simple organic molecules like lipids, carbohydrates, and amino acids could be made from inorganic compounds. Section 2 The History of Life The Theory of Endosymbiosis The ancestors of eukaryotic cells lived in association with prokaryotic cells. The relationship between the cells became mutually beneficial, and the prokaryotic organisms became organelles in eukaryotic cells. This theory explains the origin of chloroplasts and mitochondria. Section 2 The History of Life The Origin of Life ORIGIN OF LIFE ON EARTH: THERMAL VENTS One current theory is that life originated deep beneath the surface of the ocean at deep sea hydrothermal vents. These hydrothermal vents were first discovered in 1979. Previously scientists were sure that life could not exist, deep beneath the surface of the ocean. After the discovery of hydrothermal vents, they found ecosystems thriving in the depths of the ocean. ...
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