Online Counseling Resource YCMOU ELearning Drive… School of Architecture, Science and Technology Yashwantrao Chavan Maharashtra Open University, Nashik – , India

OC-SBT/SBI/SGS032-U01-02 Introduction Programmes and Courses SEP – SBT032 – Unit 01 SEP – SBI032 – Unit 01 SEP – SGS032 – Unit 01

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.3 Credits Academic Inputs by Mrs. Rasika Bhore M.sc (Microbiology)

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.4 How to Use This Resource Counselor at each study center should use this presentation to deliver lecture of minutes during Face-To-Face counseling. Discussion about students difficulties or tutorial with assignments should follow the lecture for about minutes. Handouts (with 6 slides on each A4 size page) of this presentation should be provided to each student. Each student should discuss on the discussion forum all the terms which could not be understood. This will improve his writing skills and enhance knowledge level about topics, which shall be immensely useful for end exam. Appear several times, for all the Self-Tests, available for this course. Student can use handouts for last minutes preparation just before end exam.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.5 Learning Objectives After studying this module, you should be able to: Discuss spontaneous generation is not possible. Describe theory of biogenesis. Explain the experiments done by various scientists which disproves abiogenesis.

School of Science and Technology, Online Counseling Resource… Introduction The theory of spontaneous generation by Aristotle was accepted over 1900 years. But later, many scientists have studied & performed different experiments which were disproving this theory. The new era of microbiology started after disproving this theory. Finally the accepted theory is ofbiogenesis. © 2007, YCMOU. All Rights Reserved.6

School of Science and Technology, Online Counseling Resource… Biogenesis Its reverse concept of Abiogenesis. Theory of Biogenesis simply states that living things arises only from other living things. Scientists who proved Biogenesis through different experiments are – 1.Francesco Redi 2.Lazzaro Spallanzani 3.Louis Pasteur © 2007, YCMOU. All Rights Reserved.7

School of Science and Technology, Online Counseling Resource… Francesco Redi Francesco Redi was an Italian physician who was the first to attempt to disprove the Theory of Spontaneous Generation by performing a controlled experiment. In 1668, he performed an experiment to check whether maggots (baby flies) really came from decaying meat. He did this by placing meat in a number of jars and covering half of them with fine gauze while leaving the others uncovered. © 2007, YCMOU. All Rights Reserved.8

School of Science and Technology, Online Counseling Resource… Redis Experiment Redi put meat into three separate jars: Jar #1 open (left) - He observed flies laying eggs on the meat and the eventual development of maggots. Jar #2 covered with netting (right) - Flies laid their eggs on the netting and maggots soon appeared on net. Jar #3 sealed (middle) - Flies were not attracted to this jar and no maggots developed on the meat. © 2007, YCMOU. All Rights Reserved.9

School of Science and Technology, Online Counseling Resource… Conclusion of Redis Experiment Redi concluded that the maggots did not come from the meat, but from tiny eggs that flies had laid on the meat. Since the flies could not land on the meat in the covered jars, they could not lay eggs on that meat, and no maggots formed. Therefore, decaying meat could not produce maggots. Only flies could produce maggots. Soon other scientists were able to repeat Redi's experiment, so many were convinced that living things can not come from nonliving things. © 2007, YCMOU. All Rights Reserved.10

School of Science and Technology, Online Counseling Resource… Lazzaro Spallanzani Lazzaro Spallanzani was an Italian scientist who also attempted to disprove the Theory of Spontaneous Generation, almost one hundred years after Francesco Redi's experiments. In the late 1700's, Lazzaro Spallanzani tried to disprove this by performing a controlled experiment with broth. He noted a flaw in Needhams experiment. The containers holding Needhams beef broths had not been sealed upon boiling. Spallanzani modified Needhams experiment. © 2007, YCMOU. All Rights Reserved.11

School of Science and Technology, Online Counseling Resource… Spallanzanis Experiment 1.Spallanzani put broth into two flasks (glass containers) and sterilized them both by boiling the broth. 2.One of the flasks was left open to the air. 3.The other flask was sealed up to keep out any organisms that might be floating in the air. 4.Microorganisms developed only in the uncovered flask. © 2007, YCMOU. All Rights Reserved.12

School of Science and Technology, Online Counseling Resource… Conclusion of Spallanzanis Experiment From this, Spallanzani concluded: The microorganisms did not come from the broth, but were in the air that entered the flask. Therefore, not even microorganisms came from nonliving things. © 2007, YCMOU. All Rights Reserved.13

School of Science and Technology, Online Counseling Resource… Louis Pasteur Pasteur, a French scientist who made great contributions to our understanding of microbiology and for whom the process of pasteurization is named,. Repeated experiments similar to those of Spallanzani's and brought to light strong evidence that microbes arise from other microbes, not spontaneously. © 2007, YCMOU. All Rights Reserved.14

School of Science and Technology, Online Counseling Resource… Pasteurs Swan Necked Flask Pasteur created unique glass flasks with unusual long, thin necks that pointed downward. These swan-necked flasks allowed air into the container but did not allow particles from the air to drift down into the body of the flask. © 2007, YCMOU. All Rights Reserved.15

School of Science and Technology, Online Counseling Resource… Pasteurs Experiment One flask had a straight neck that both air and microorganisms could enter. The other flask had an S-shape neck that allowed air in, but not microorganisms. The broth in the straight neck flask became contaminated with microorganisms. The broth in the flask with an S-shaped neck did not become contaminated. © 2007, YCMOU. All Rights Reserved.16

School of Science and Technology, Online Counseling Resource… Observation from Experiment Thus, Pasteur found that these swan-necked containers would remain free of microbes until he either broke the necks of the flasks, allowing particles from the air to drift in, or until he tilted the flask so that the liquid came in contact with dust that had accumulated at the opening of the flask. © 2007, YCMOU. All Rights Reserved.17

School of Science and Technology, Online Counseling Resource… Conclusion of Pasteur's Experiment Even though air could get in the flask, the broth did not produce microorganisms. Scientists finally were convinced that living things, no matter how small, do not come from nonliving things. © 2007, YCMOU. All Rights Reserved.18

School of Science and Technology, Online Counseling Resource… What we Learn………. Theory of biogenesis states that life comes only from living things. Redis experiment prove that maggots do not come from meat, it come from egg. Spallanzani proved that microbes come from air & not from nonliving things. Finally the Pasteur's experiment which is widely accepted proven that living things arises from other living things only. © 2007, YCMOU. All Rights Reserved.19

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.20 Critical Thinking Questions Design an experiment to prove that microbes do not spontaneously generate in milk.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved. Tips For Critical Thinking Questions You can follow Pasteur's experiment.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.22 Study Tips Book Title: Microbiology Author: Robert W. Bauman Book Title: Burtons Microbiology Author: Wilson Burton

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.23 Study Tips Biogenesis- the free encyclopedia Life science connections

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