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Microbio dates back to 200 years, but the recent discovery of __
DNA in __ reminds us that microorganisms have been around for much longer
Bacterial ancestors were the first living cells to appear on Earth
- Mycobacterium tuberculosis
- 3000-year old Egyptian mummies
The First Observations
1) discovered cells--> cell theory (all living things are composed of cells)
2) AvL: observed live microorganisms through his microscope--> drew "animalcules" that he found in rainwater, his feces, and in material from his teeth
ii. Until the second half of the 19th century, many scientists and philosophers believed that some forms of life could arise spontaneously form nonliving matter; they called this __
Con Spontaneous Generation
--> Francesco Redi
- two jars with decaying meat
- one covered-> no maggots
- one uncovered--> maggots
jar with fine net--> air present and no maggots
Pro SG: John Needham
heated nutrient fluids (broth) before pouring into covered flasks--> cooled solutions had microbes
suggested that Needham's experiment was contaminated with microbes after the boiling process and redid the experiment, showing that the flask, after being directly covered, teemed with no microbes
Spallanzani was refuted by __, who claimed that __.
there was no vital force present, which is necessary for SG
Pro: Anton Lavoisier
- claimed hwat?
Spallanzani’s observations were criticized on the groups that there was not enough oxygen in the sealed flasks to support microbial life
The Theory of Biogenesis:
a. Issue was unresolved in 1858, until __ challenged the case of spontaneous generation with the concept of __, the claim that __
What was the result of his research?
living cells can arise only from preexisting living cells
--> no proof--> issue still unresolved until finally resolved by Louis Pasteur
a. Pasteur demonstrated that microorganisms are present in the air and can contaminate sterile solutions, but that air does not create microbes.
How did he do this?
Exp. 1: Filled short-necked flasks with beef broth and boiled ità some left open and allowed to coolà microbes; Other flasks that were sealed after boiling were free of microorganisms
- Experiment 2: placed broth in open-ended long-necked flasks and bent the necks into S-shaped curveà contents boiled and cooledà no life because design of flask allowed air to pass into the flask, but the curved neck trapped any airborne microorganisms that might contaminate the broth
Pasteur showed that microorganisms can be __; also, he demonstrated that microbial life can be __
- present in nonliving matter and in air
- destroyed b heat and blocked by methods
These experiments led to __
, techniques that prevent contamination by unwanted microorganisms
Pasteur’s work provided evidence that microorganisms cannot originate from mystical forces present in nonliving materials; they were already present
Why is the period from 1857 to 1914 considered the Golden Age of Microbiology?
Rapid advances (mainly Koch and Pasteur)
Discoveries including agents of diseases and role of immunity in preventing and curing disease
microbiologists studied chem acivities of miroorganisms, improved microscopic techniques and culturing, and developed vaccines and surgica techniques
i. Question posed to Pasteur: Why does wine and beer get sour?
Answer and Solution?
- 1. Answer: Microorganisms called yeasts convert the sugars to alcohol in the absence of air, called fermentation, which is used to make wine and beer
- a. Souring and spoilage are caused by bacteria, which change the alcohol into vinegar (acetic acid)
Solution: heat beer and wine just enough to kill most of the bacteria, called pasteurization, which is used to reduce spoilage and kill harmful bacteria in milk and alc
Before Pasteur’s time, effective treatments for many diseases were discovered by __, but causes were unknown
The discovery of __ was the first link between the activity of a microorganism and physical and chemical changes in organic materialsà
led to the idea that __--> __
- trial and error
- yeasts and fermentation
- microorganisms might cause disease
germ theory of disease
Belief of disease at first?
Disbelief of disease?
"invisible" microbes could travel thorugh air to infect plants and animals or remain on clothing and bedding to be transmitted from one person to another
In 1865, Pasteur was called upon to help __
Before this, in 1835, __, an amateur microscopist, proved that another __ was caused by a __; and, using his data, Pasteur found that the more recent infection was caused by a __, and he developed a method for __
- fight silkworm disease, which was ruining the silk industry
- Agostini Bassi
- silkworm disease
- recognizing afflicted silkworm moths
In the 1860s, __, an English surgeon, applied the germ theory to medical procedures.
He was aware that in the 1840s, the Hungarian physician __ had demonstrated that __; and, he heard of Pasteur’s work connecting microbes to animal diseases
- Joseph Lister
- Ignaz Semmelweis
- physicians, who at the time did not disinfect their hands, routinely transmitted infections among patients
So, what did Lister do?
used phenol to kill bacteria and treat surgical wounds, thus reducing infections and death
proved taht microorganisms cause surgical wound infections
In 1876, the first proof that bacteria actually cause disease came from __, Pasteur’s rival in race to discover __
- Robert Koch
- cause of anthrax
What did Koch discover?
Discovered rod-shaped bacteria in the blood of cattle that died of ità
cultured bacteria on nutrients and injected samples of culture into health animalsà
animals got sick and diedà
he examined their bloodà
same bacteriaà Koch’s postulates
What is Koch's postulates?
A sequence of experimental steps for directly relating a specific microbe to a specific disease
On May 4, 1796, Edward Jenner embarked on an experiment to do what?
find a way to protect people from smallpox
Explain Jenner's experiences and experiment
- 1. A young milkmaid told him she couldn’t get smallpox because she had it already, he studied this
- a. First, he collected scraping from cowpox blisters and inoculated a healthy 8 year old volunteer with the cowpox material via a needle and exposed her to ità she got mildly sick but lived and never got smallpox or cowpoxà vaccination
The protection from disease provided by vaccination (or by recovery from the disease) is called __
Years after, Pasteur understood why they work
The bacterium that causes fowl cholera lost its ability to cause disease after grown in the lab for a while, but it did do what?
Jenner’s experiment marked the first time in a Western culture that what?
induce immunity against later infections by its virulent counterparts
a living viral agent –the cowpox virus – was used to produce immunity