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Theories of the Origin of Life Is the veal using its meaty powers to create maggots from itself? Spontaneous Generation The theory of life arising out of nonliving matter. Francesco Redi Began the work to disprove the theory of spontaneous generation. Redi’s Experiment Redi used a number of different containers. He placed meat, fish, etc. in them. He noticed that the containers which were closed did not display the theory of spontaneous generation. Only containers which were left open to the air displayed the theory of spontaneous generation— maggots grew out of the meat, fish, etc. Redi’s Experiment Louis Pasteur Provided the final nail on the coffin of the theory of spontaneous generation! Pasteur’s Experiment Pasteur decided to disprove the remaining evidence to the theory of spontaneous generation—which dealt with the idea that although macro-organisms, like maggots and mice, could not be created from non-living items, mold and bacteria could. He took some broth and heated it up in flasks which were open to the air. As predicted, the broth became dark in color as bacteria grew in it. He believed that bacteria were floating in the air, and wanted to prove this by making it impossible for these bacteria to reach the broth. Pasteur’s Experiment Therefore, he chose to use some flasks which had swan necks, and some flasks which were open to the air. The flasks which were open to the air became cloudy as bacteria began to grow from the heated broth. However, the broth which was heated in the flasks with the swan necks remained clear!! Instead, bacteria and dust particles accumulated in the lower portion of the neck of the flask—proving that the bacteria came from the air, and not from the broth. This helped to completely disprove the theory of spontaneous generation. Interactive Version of the Experiment http://bcs.whfreeman.com/thelifewire/content/ch p03/0303s.swf Abiogenesis So… the theory of spontaneous generation has been disproved, but how did life, then, arise in our world? The theory of abiogenesis helps to explain this. The theory of abiogenesis refers to the origin of life—how it was created out of nonliving matter. Although somewhat similar to the theory of spontaneous generation, this theory refers to how the first living organisms were created out of “nothing!” Abiogenesis A = “not” Bio = “life” Genesis = “birth” or “creation” Abiogenesis is the birth or creation of life from nonliving things. In other words, the origin of life came from nonliving items! Small molecules came together to form nucleic acids which in turn managed to enter some sort of circular layer of fat which could now self-replicate, creating the first organisms! Miller-Urey Experiment The Miller-Urey experiment is an experiment which proved the theory of abiogenesis. These two researchers created an apparatus which heated up water containing certain basic molecules such as CO, CH4, H2, etc. As the solution was heated, the vapor of the solution traveled through the apparatus and was shocked with electrodes. This shocking process was to mimic the lightning which was believed to occur frequently in ancient earth. Miller-Urey Experiment As these molecules went through the system, the liquid became darker and darker. When Miller and Urey checked the liquid, they saw that nucleotides had formed in the solution!! Therefore, the conditions of ancient Earth could have, by themselves, allowed the initial molecules to join together to create life (GENESIS of BIO) out of nonliving (ABIOTIC) factors. Miller-Urey Experiment Exit Slip Is the theory of spontaneous generation credible? Please provide your reasons why. How does it differ from abiogenesis?