Mis tareas
The Importance of Microorganisms
Chapter 1 The History and Scope of Microbiology
Most populous group of organisms and are
found everywhere on the planet elements
Play a major role in recycling essential Source of nutrients and some carry out
photosynthesis
Benefit society by their production of food,
beverages, antibiotics and vitamins
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Whatis microbiology?
Study of organisms too small to be clearly
Members of the microbial world
procaryotic cells lack a true membrane-delimited
seen by the unaided eye (i.e., microorganisms)
These organisms are relatively simple in their
nucleus
eucaryotic cells have a membrane-enclosed
construction and lack highly differentiated cells and distinct tissues
nucleus, are morecomplex morphologically and are usually larger than procaryotic cells
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Classification schemes
Five kingdom scheme includes Monera,
Protista, Fungi, Animalia and Plantae with microbes placed in the first three kingdoms
Three domain alternative, based on a
comparison of ribosomal RNA, divides microorganisms into Bacteria (true bacteria), Archaea andEucarya (eucaryotes)
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Domain Bacteria – all procaryotic
Most are single-celled Most have peptidoglycan in cell wall Can survive broad range of environments Most are non-pathogenic and play major role in
Domain Archaea – all procaryotic
Procaryotic Distinguished from bacteria by unique
ribosomal rna sequences
Lack peptidoglycan in cell wall Many found in extremeenvironments
nutrient recycling
Cyanobacteria produce oxygen as a result of
photosynthesis
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No pathogenic species known
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Domain Eucarya – all eucaryotic
Animals, plants and eucaryotic
Viruses
Acellular
microorganisms
Microorganisms include protists
Smallest of all microbes Cause a range of diseases including
(unicellular algae, protozoa,slime molds and water molds) and fungi
Most are larger than procaryotic cells
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some cancers
Discovery of Microorganisms
Antony van
Leeuwenhoek (1632-1723)
first person to
observe and describe microorganisms accurately
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The Conflict over Spontaneous Generation
Spontaneous generation Living organisms can develop from nonliving
Butcould spontaneous generation be true for microorganisms?
John Needham (1713-1781) His experiment:
Mutton broth in flasks boiled sealed
or decomposing matter
Francesco redi (1626-1697) Disproved spontaneous generation for large
Results: broth became cloudy and contained
microorganisms
Lazzaro Spallanzani (1729-1799)
His experiment:
animals Showed that maggots ondecaying meat came from fly eggs
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Broth in flasks sealed boiled
Results: no growth of microorganisms
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Louis Pasteur (1822-1895)
His experiments Placed nutrient solution in flasks Created flasks with long, curved necks Boiled the solutions Left flasks exposed to air Results:no growth of microorganisms
Louis Pasteur (1822-1895)
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Final blow to theory of spontaneous generation
John Tyndall (1820-1893)
Demonstrated that dust carries
The Role of Microorganisms in Disease
Was not immediately obvious Establishing connection depended on
microorganisms
Showed that if dust was absent, nutrient
broths remainedsterile, even if directly exposed to air
Also provided evidence for the existence of
development of techniques for studying microbes
Once established, led to study of host
exceptionally heat-resistant forms of bacteria
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defenses - immunology
The golden age of microbiology (1857-1914)
Many disease producing organisms
discovered
Microbial metabolism studies undertaken ...
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