1. I. How Did Life Come to Be? - Theories A.Dark Ages: “Life arose from non-living matter.” This process is known as spontaneous generation Ex: -rats from dirty clothes -frogs from mud -maggots from rotting meat

2. B. The Renaissance 1) 1668: An Italian doctor named Francesco Redi proposed the theory of biogenesis “life comes from life” He designed an experiment to test his theory I. How Did Life Come to Be? - Theories

3. Redi’s Experiment Hypothesis = maggots come from eggs, not rotting meat Control Treatment- No lid

4. Experimental Treatment #1 – Lids Experimental Treatment #2 – Screens Redi’s Experiment Proved Biogenesis!!!

6. So….how do spontaneous generation and biogenesis tie into Microbiology?

7. I. How Did Life Come to Be? - Theories B.The Renaissance (continued) 2) 1745 – John Needham tried to prove that spontaneous generation was correct Steps to Experiment: -boiled broth -sealed broth -bacteria grew He felt this proved that bacteria (living) came from broth (non-living) after killing all existing bacteria in the broth…why might this not be true?

8. I. How Did Life Come to Be? - Theories B.The Renaissance (continued) 3) 1770 – Lazzaro Spallanzani was an Italian priest who believed Needham did not boil the broth long enough to kill all existing bacteria Steps to Experiment: -Boiled broth longer -Sealed broth -Found NO BACTERIA LONGER!

9. I. How Did Life Come to Be? - Theories B.The Renaissance (continued) 4)1862 – Louis Pasteur did another experiment with broth, which led to the concept of pasteurization

10. Pasteur’s Experiment 2 different set-ups: Control vs. Experimental Control Treatment: boiled broth in an open neck flask…a year later found bacteria in flask Open Neck Flask

11. Experimental Treatment: boiled broth in a closed neck flask (swan neck keeps bacteria from entering)… a year later found NO bacteria Pasteur’s Conclusion: Spontaneous Generation is FALSE Swan Neck Flask

13. How do the ideas presented by Spallanzani and Pasteur relate to everyday life? If their contributions did not exist, would there be any negative ramifications in society today?

14. Pasteurization Pasteur discovered that heating milk to a high temperature then swiftly cooling it before bottling it, enabled the milk to remain fresher for an extended period of time. Today the process of pasteurization is used widely in the drinks and food industry. This process slows spoilage caused by microbial growth. Unlike sterilization, pasteurization is not intended to kill all micro- organisms in the food. Instead, it aims to reduce the number of viable pathogens so they are unlikely to cause disease. Commercial-scale sterilization of food is not common because it adversely affects the taste and quality of the product. Certain foods, such as dairy products, may be superheated to ensure pathogenic microbes are destroyed. According to the United States Centers for Disease Control between 1998 and 2011 79% of the dairy related outbreaks were due to raw milk or cheese products.

15. Writing Prompt On a separate piece of paper, explain why it took so long for people to accept that spontaneous generation is not a viable theory. Furthermore, write about today’s society in your response- do you think that scientific ideas and discoveries are accepted quicker today than they were in previous centuries? Provide your reasoning. Complete sentences/paragraphs Trade and peer-review Two piles: Bedford & Martinez