Micro Chapter 1 Short Answers

Refer to the four steps in the scientific method in describing Pasteur's fermentation experiments.

1) A group of observations leads a scientist to ask a question about some phenomenon. 2) The scientist generates a hypothesis 3) The scientist designs and conducts an experiment to test the hypothesis. 4) Based on the observed results of the experiment, the scientist either accepts, rejects, or modifies the hypothesis. " What causes fermentation"? 1st hypothesis:spontaneous fermentation He heated a flask of grape juice to kill microbes and sealed it. No fermentation occured, the grape juice had no microorganisms. He rejected his hypothesis. 2nd hypothesis: air causes fermentation He heated a flask of grape juice to kill microbes. Swan neck flasks were used to allow air. No fermentation occured. He rejected his hypothesis. 3rd hypothesis: bacteria ferments grape juice into wine He heated the grape juice in a flask and inoculated it with bacteria and sealed. The grape juice got cloudy as the bacteria grew. The bacteria fermented the grape juice into acid. He rejected his hypothesis. 4th hypothesis: yeast ferments grape juice He heated the flask of grape juice just enough to kill the bacteria, inoculated the juice with yeast, and sealed the flask.The yeast fermented and alcohol was produced. He accepted his hypothesis. In answering the question "What causes fermentation"? he learned that yeast ferments into alcohol, and that yeast could grow with or without oxygen. He also discovered pasteurization as a way of keeping foods from spoiling.

List Koch's Postulates and explain why they are significant.

1) The suspected causative agent must be found in every case of the disease and be absent from healthy hosts. 2) The agent must be isolated and grown outside the host. 3) When the agent is introduced into a healthy host , the host must get the disease. 4) The same agent must be found in the diseased experimental host. His postulates provide a framework for proving the role of microbes in disease.They tell us how to definitively prove that a particular microbe causes a given disease.

Discuss the significant difference between the flasks used by Pasteur and Spallanzani. How did Pasteur's investigation settle the dispute about spontaneous generation?

Both scientists boiled their infusion long enough to kill everything. Spallanzani used vials and sealed them by melting the necks closed, allowing no air to enter. Pasteur used swan neck flasks which allowed air to enter but not dust and microbes. Spallanzani's vials remained clear until he broke the necks off his vials. Though Spallanzani showed no spontaneous generation with his experiment, it was said that he sealed his vials and allowed no air for organisms to survive. Aristotle's 2000 year old theory was not disproved. Pasteur, after 18 months, had no microbial growth in his flasks. He tilted some of the flasks, allowing the dust settled in the curve of the neck to mix with the infusion. He also broke the neck off some other flasks, exposing the liquid to the air. The next day the flasks were cloudy with microbial growth. Pasteur said "Never will spontaneous generation recover from the mortal blow of this simple experiment."

Why would a macroscopic tapeworm be studied in microbiology?

Even though most of these worms are not microscopic as adults , many of them cause diseases that were studied by early microbiologists. Infections of tapeworms were diagnosed by finding microscopic eggs and immature stages in the blood, fecal, urine, and lymph specimens.

Describe what has been called the "Golden Age of Microbiology" with reference to four major questions that propelled scientists during that period.

For about 50 years, from the late 1800's to the early 1900's, during what is now called "The Golden Age of Microbiology", scientists were driven by the search for answers to the following 4 questions: 1- Is spontaneous generation of microbial life possible? 2- What causes fermentation? 3- What causes diseases? 4- How can we prevent infection and disease? During these years the question of spontaneous generation was studied by Redi, Needham, Spallanzani, and ended with the results of Pasteur finally disproving the theory. Fermentation was figured out by Pasteur while trying to figure out why wines sometimes spoiled. He learned pasteurization would kill the bacteria that caused spoilage and living yeast would ferment into alcohol. This began the field of industrial microbiology. Buchner proved that fermantation did not require living cells, but enzymes. This began the field of biochemistry and the study of metabolism. The question of what caused disease was previously though to be attributed to evil spirits, astrological signs, imbalances in body fluid and foul vapors. Pasteur's discovery that bacteria causes wine to spoil led to his hypothesis that microorganisms are responsible for disease, which became know as the germ theory of disease. Semmelweis, Lister, Nightingale, and Snow introduced aseptic techniques for treating patients in a hospital or clinical setting after it had been discovered that the health care givers were themselves infecting the patients. This began the field of infection control and epidemiology. Vaccinations were first discovered by Jenner with his vaccine of cowpox to prevent smallpox. This began the field of immunology. Ehrlich investigated the idea that chemicals could be used to kill microorganisms differentially. He discovered chemicals active against protozoans that caused African Sleeping Sickness and Syphilis. This began the field of chemotherapy.

Defend this statement: "The investigations of Antoni van Leeuwenhoek changed the world forever."

Leeuwenhoek was a Dutch tailor, merchant, and a lens grinder. He had a stubborn desire to do everything himself. He learned to make his own magnifying lenses to examine the quality of cloth. He began looking at all kinds of things under his lenses out of curiosity. He began making simple microscopes and this became an over-whelming passion for him. He made a new microscope for each new specimen he viewed. One day he turned a lens to a drop of water. He discovered a previously unknown microbial world he called animalcules.This began the study of micrbiology.

Why can Pasteur be honored with the title "Father of Microbiology"?

Pasteur can be honored with this title because of his many, varied, and significant accomplishments in working with microbes. He resolved the theory of spontaneous generation, discovered what causes fermentation and how to keep foods from spoiling (pasteurization). He also hypothesized that microorganisms cause disease, which brought about the germ theory of disease. Pasteur capitalized on Jenner's small pox vaccine by producing weakened strains of various pathogens for use in preventing the serious diseases they caused. He developed successful vaccines against fowl cholera, anthrax, and rabies.

Why was the theory of spontaneous generation a hindrance to the development of the field of micrbiology?

Spontaneous generation, proposed by Aristotle, was believed for 2000 years. Experiments with meat were done by Redi to disprove the theory and scientists began to doubt Aristotles theory. Needham tested the theory with boiled infusion in corked vials, only to show spontaneous generation was true. Spallanzani also tested the theory with boiled infusion and he sealed his vials by melting the necks to not allow any air to enter. Although his experiment showed no spontaneous generation it was said that his sealed vials did not allow air for organisms to thrive. The theory of spontaneous generation continued. Pasteur is the one who finally disproved the theory with his swan neck flask experiment in the 1800's. It was then that microorganisms began being studied in depth.

List 6 types of microorganisms.

fungi protozoa algae bacteria archaea viruses