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Major groups of organisms studied in microbiology
- bacteria
- algae
- fungi
- viruses
- protozoa
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Bacteria (bacterium)
- single celled
- spherical rod
- spiral shaped
- a few forms filements
- do not have cell nucleus
- many gain nutrients from environment
- some make their own by photosynthesis or other synthetic process
- some move while some are stationary
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algae(alga)
- single-cell microscopic organism
- some marine algae are large and multicellular
- has nucleus
- photosynthesize their own food
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fungi (fungus)
- single-celled microscopic organism
- some are multi-cellular and macroscopic
- example: mushroom
- have nucleus
- absorb ready-made nutrients from environment
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Viruses
- are acellular, which makes them too small to be seen by a light microscope
- they are composed of specific chemical substances
- a nucleic acid, a few proteins
- replicate themselves and show characteristics of other living cells
- small acellular agents of disese are : viroids, pirons
- viroids: casue plant disease- nucleic acid without a protein coating
- pirons: cause cow disease-protein without any nucleic acid
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protozoa(protozoan)
- single-cellular microscopic organism
- with at least 1 nucleus
- gets food by engulfing or ingesting smaller micro-organism
- they can move; those that don't move cause human disease
- they can be found in water and soil environments as well as animals
- example: malarious mosquitoes
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bacterophage(phage)
a virus that infects bacteria
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microorganism (microb)
organisms studied with a microscope also includes viruses
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Cell theory
- cells that are the fundamental units of life and carry out all the basic functions of living things
- now it applies to all cellular organisms, but viruses
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germ theory of disease
states that germs (microorganisms) can invade other organisms and cause disease
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spontaneous generation
the theory that living organisms can arise from non-living things
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antibiotics
a chemical substance that was produced to enter microorganisms that can inhibit the growth of destroy other microorganisms
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hypothesis
a tentative explanation for an observed condition or event
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prediction
the expected outcome if a hypothesism is correct
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experimental variable
the factor that is purposly changed in an experiment
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control variable
a factor that is prevented from changing during an experiment
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conclusion
end result of an analysis of experimental result
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koch postulates
- 1.) the specific causative agent must be found in every case of the disease
- 2.) the disease organism must be isolated in pure culture
- 3.) inoculation of a sample of the culture into a healthy susceptible animal must produce the same disease
- 4.) the disease organism must be recovered from inoculated animal
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Microorganism are useful in research for at least 3 reasons:
- 1.) microbs have simple structures. it is easier to study life process in simple unicellular organisms than in complex multicellular ones
- 2.) Large number of microorganisms can be used in experiments at a reasonable cost, to obtain statistically reliable results
- example: growing billions of bacteria is cheaper to maintain than 10 rats
- 3.) microorganisms reproduce quickly, which maybe useful to studying the transfer of genetic information. some bacteria can undergo 3 cell division in 1 hour
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