Chapter 1 Flashcards
Who was Anton ie Van Leeuwenhoek?
He described microorganisms through his simple microscope and called them “animalcules”
Microbe
Refers to general members of the microbial world
Spontaneous Generation
The discredited belief that organisms can arise from non living matter
What was Francesco Redi’s experiment?
Redi covered meat with fine gauze that prevented flies from depositing their eggs. When he did this, no worms appeared
What did Redi’s experiment show?
Worms found on rotting meat originated from fly eggs, not from the decaying meat as supporters of spontaneous generation believed .
What did John Needham do?
Showed that flasks with various broths gave rise to microorganisms even when the flasks were boiled and sealed with a cork. This suggested that microorganisms did indeed arise spontaneously.
Whose was Lazzaro Spallanzani and what did he do?
Animal physiologist and priest
Got results that contradicted Needham.
No bacteria appeared in Spallanzani’s broths after boiling.
How did Spallanzani’s experiment differ from Needham’s?
Differed in two way:
1. Spallanzani boiled the broths for longer periods
- Spallanzani sealed the flasks by melting their glass necks closed.
Using these two techniques, he showed that the broths remained sterile.
If the neck of the flask cracked, the broth rapidly became cloudy due to growth of microorganisms
What did Spallanzani conclude from the experiment?
Microorganisms has entered the broth with the air and the corks used by Needham did not keep them out.
Why didn’t Spallanzani’s experiment stop controversy?
Some people argued that heating process destroyed “vital force” in the air that was necessary for spontaneous generation.
Whose is considered “The Father of Microbiology”?
Louis Pasteur
What did Louis Pasteur demonstrate?
Air contains microorganisms
He demonstrated that sterile broths in specially constructed swan necked flasks remained sterile even when left open to air
How did Pasteur demonstrate that air contains microorganisms?
He filtered air through a cotton plug, trapping microorganisms.
Then he examined the trapped microorganisms with a microscope and found that many looked identical to those described by others who had been studying broths.
When Pasteur dropped the cotton plug in sterilized broth, the broth became cloudy from the growth of these microorganisms.
Theory of Biogenesis
The production of living things from other living things.
What did John Tyndall do?
Many people could not replicate Pasteur’s results. Tyndall found that various types of broths required different boiling times to be sterilized
What did John Tyndall conclude about microorganisms?
Concluded that some microorganisms exist in two forms:
- A cell easily killed by boiling
- One that is heat resistant
Ferdinand Cohn
Discovered endospores
Endospores
Resistant dormant cell produced by some types of bacteria.
They are heat resistant forms of some bacteria.
This explains difference between Pasteur’s results and others.
Germ Theory of Disease
The suggestion that microorganisms cause certain disease
Theory
An explanation supported by extensive amount of experimental evidence.
Normal microbiota (or normal flora)
Group of microorganisms that colonize the body surfaces but do not usually cause disease.
Composition of normal microbiota can affect brain chemistry and behavior.
“Old Friends Hypothesis”
Early exposure to certain common microorganisms lessens the likelihood that an individual will develop allergies, asthma and some other diseases.
This early exposure helps the immune system learn to distinguish friendly microbes from those that can cause severe disease.
Human Microbiome Project
Microbiome (2 meanings)
- Total genetic content of microbial community
- The microbial community itself
