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Microbiologyunit1/2
unit 1-2
| Question | Answer |
|---|---|
| For about 50 years, during the golden age of microbiology, scientists were driven by the search of the following questions: | • Is spontaneous generation of microbial life possible? What causes fermentation?• What causes disease?• How can we prevent infection and disease? |
| Who is knowen for “Origin of Life” | Aristotle (384-322 B.C.) |
| • Aristotle Proposed the theory of spontaneous generation also called | abiogenesis |
| • Aristotle Idea that living things can arise from | nonliving matter |
| • Aristotle Idea lasted almost ---- years! - | 2000 |
| • Many philosophers and scientists of past ages thought that organisms could develop from nonliving matter | spontaneously come to life spontanious generation theory |
| • Archaic theory applied to explain the ? | origin of life. |
| • Example - Pieces of cheese and bread wrapped in rags and left in a dark corner, were thought to produce mice, because after several weeks, there were mice in the rags. | . |
| • 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 | . |
| • Observation: Since there were no refrigerators, the mandatory daily trip to the butcher shop, especially in summer, meant battling flies around carcasses. | • Conclusion: Obviously, the rotting meat that had been hanging in the sun all day was the source of the flies. |
| Disproving the Theory of Spontaneous Generation | Redi’s Experiments |
| • In 1668, who did an experiment with flies and jars containing meat | Francesco Redi Redi’s Experiments |
| • Redi hypothesized that rotten meat does not turn into | flies |
| • Redi observed these flasks to see in which one(s) maggots would | develop in Redi’s Experiments |
| Evidence against spontaneous generation: | 1. Unsealed – maggots on meat, 2. Sealed – no maggots on meat 3. Gauze – few maggots on gauze, none on meat |
| The results of this experiment disproved the idea of spontaneous generation for larger organisms, but people still thought that | microscopic organisms like algae or bacteria could arise that way. |
| Disproving the Theory of Spontaneous Generation of microbes | Anton van Leeuwenhoek |
| who was knowen as the “Master of the Microscope” | Anton van Leeuwenhoek |
| • in 1673 who– developed simple microscope like magnifying glass | Anton van Leeuwenhoek |
| • Examined water – saw “animalcules” and “beasties” | Anton van Leeuwenhoek |
| • Was the first to report the existence of protozoa (1674) and bacteria (1676) | Anton van Leeuwenhoek |
| • Submitted observations/drawings to the Royal Society of London | Anton van Leeuwenhoek |
| • Raised the question – “What does life really look like” and “Where do they come from?” | Anton van Leeuwenhoek |
| • By 1860, the debate had become so heated that the Paris Academy of Sciences offered a prize for any experiments that would help resolve this conflict | . |
| • The prize was claimed in 1864 by Louis Pasteur - published the results of an experiment that disproved spontaneous generation in microscopic organisms | . |
| Hypothesis: Microbes come from cells of organisms on dust particles in the air; not the air itself. | Pasteur’s Swan Neck Experiment |
| After a long period, the broth medium still did not turn cloudy;therefore, no microbes were present | Pasteur’s Swan Neck Experiment |
| Proved microbes only come from other microbes (life from life) –biogenesis. Louis Pasteur's disproved spontaneous generation | Pasteur’s Swan Neck Experiment |
| • The bended neck allowed air to enter the bottle and the liquid but trapped any particulates including microorganisms. | Pasteur’s Conclusions |
| • No microbial growth as long as the liquid broth did not come in contact with the microbes.• Hence air alone was not sufficient to generate life. | Pasteur’s Conclusions |
| Who was knowen as – “Germ Hunter” | Louis Pasteur |
| • 1861 – definitive proof against spontaneous generation through “swan neck flask” experiments | Louis Pasteur |
| • His work led to the development of methods for controlling the growth of microorganisms | Louis Pasteur |
| • Developed Pasteurization to aid the wine industry Introduced the “Germ Theory of Disease” | Louis Pasteur |
| ? is the process of heating liquids for the purpose of destroying viruses and harmful organisms such as bacteria, protozoa, molds, and yeasts. | Pasteurization |
| • Recall SGT – disease was spontaneously generated instead of being created by microorganisms which grow by reproduction | spontanious generation theory |
| microorganisms are the cause of many diseases. | • Germ Theory - |
| • Was highly controversial but now a cornerstone of modern medicine and clinical microbiology | Germ Theory |
| • Led to important innovations like antibiotics and hygienic practices | Germ Theory |
| Who is knowen as “The Postulator” | Robert Koch |
| • Developed a set of postulates to prove that a specific microorganism causes a specific disease – | “Koch’s postulates” – B. anthracis causes anthrax (1876) – M. tuberculosis causes tuberculosis |
| • Introduced solid medium (agar) and the inoculating loop | Robert Koch – |
| Koch’s Postulates are | 1. Microbe present in EVERY instance of disease and absent in healthy subjects , 2. Microbe must be isolated and grown in pure culture, 3. Introduction of microbe must result in disease development |
| A culture containing a single kind of microorganism is what kind of culture | Pure Culture |
| What are the Limitations of Koch’s Postulates | • Viruses cannot be grown in vitro, • The model of a healthy organism is a mouse, will we see the same results in humans?, • Some diseases caused by more than one microbe • Some microbes cause more than one disease |
| Benefits of Koch’s Postulates are | • Pure cultures – revolutionized Microbiology, • Cause of Tuberculosis determined to be Mycobacterium tuberculosis, • Nobel Prize for work with Tuberculosis and Anthrax |
| who is knowen for coming up with – “Penicillin in his Petri Dish” | Sir Alexander Fleming |
| • who discovered the first antibiotic in 1928 | Sir Alexander Fleming 1928 |
| • who helped Lead to the discovery of other antibiotic sources | Sir Alexander Fleming |
| The antibiotic secreted by the Penicillium fungus during its growth inhibits the growth of bacteria. | |
| The Emergence of Antibiotics • Antibiotic – a microbially produced substance (or synthetic derivative) that has antimicrobial properties. | |
| • Most important attribute of an antibiotic is selective toxicity, (others listed on p.357-358). | |
| • Today, we are still creating and discovering new antibiotics. | |
| • Trying to obtain a pure culture• Requires a sterile nutrient-containing medium in which to grow the organisms. | |
| • You will use Aseptic Technique - Method of transferring growing organisms (called the inoculum) from a pure culture to a sterile medium without introducing any unwanted outside contaminants. | |
| Koch’s Postulates are | 4. Same microbe must be isolated from experimentally infected subject |
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kfroel4