Transcript
Scope of Microbiology
Bacteria
Simple, single-celled organisms (unicellular)
Prokaryotes: genetic material is not enclosed in special nuclear membrane.
Cell wall primarily composed of carbohydrate and proteins called peptidoglycan.
Reproduce via division (binary fission).
Archaea
Prokaryotic like bacteria, but lack peptidoglycan in cell walls.
Often found in extreme environments.
Three groups:
Methanogens: produce methane as waste product from respiration.
Extreme halophiles: lives in salty environments.
Extreme thermophiles: lives in hot sulfurous water.
Not known to cause disease in humans.
Fungi
Eukaryotes: organisms whose cells have a distinct nucleus containing DNA surrounded by nuclear membrane.
Unicellular or multicellular.
Protozoa
Unicellular eukaryotic microbes.
Reproduce sexually or asexually.
Algae
Photosynthetic eukaryotes.
Cell wall composed of carbohydrates called cellulose.
Needs light, water, and CO2, does not need organic compounds from environment.
Produces oxygen and carbs used by other organisms.
Viruses
Acellular (not cells).
Core consists of only one type of DNA or RNA.
Reproduce only by using the cellular machinery of other organisms.
Historical Roots
Cell Theory: all living things are composed of cells.
Microscopes:
Hooke first saw cells, but could not see microorganisms.
Anton van Leeuwenhoek developed microscope to see live microorganisms.
Spontaneous Generation:
Theory that some forms of life could arise spontaneously from nonliving matter.
Francesco Redi: disproved SG via maggot experiment.
First experiment
2 jars with decaying meat, one sealed one not sealed.
Open jar had maggots, sealed one did not thus disproving SG.
Second experiment
Repeat first, but sealed with gauze to allow oxygen.
Same results
Biogenesis:
Theory that living cells arise only from preexisting living cells.
Louis Pasteur: Proved that microorganisms are present in the air and can contaminate sterile solutions, BUT air itself does not create microbes.
Experiment:
Part 1:
Short-necked flasks filled with broth and boiled.
Some left open-had microbes, some sealed-no microbes.
Conclusion: Microbes in the air were responsible for contaminating nonliving matters.
Part 2:
Placed broth in open-ended swan-neck flasks.
Broth did not decay or show sign of life.
Swan-neck flask trapped any airborne microorganisms that could contaminate broth.
Overall Conclusion:
Microorganisms can be present in non-living matter.
Microbial life can be destroyed with heat.
Methods can be used to block the access of airborne microorganisms to nutrient environment.
Forms the basis of aseptic techniques: procedures that prevent contamination by unwanted microorganisms.
Germ Theory
Theory that postulates that microorganisms might cause disease.
Joseph Lister: Used phenol (carbolic acid) to treat surgical wounds and reduce the infection/death rate.
Robert Koch: established Koch's postulate after studying bacteria in cattle for anthrax.
Koch's Postulates: sequence of experimental steps to identify the causative agent of a particular disease, these include: the microorganism or other pathogen must be present in all cases of the disease.
Carolus Linnaeus
Introduced a formal system of classification with two kingdoms: Plantae and Animalia.
Taxonomy: organization of organisms into categories, or taxa, to show degrees of similarities among organisms.
