1
Q
Microbiology
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The study of “small organisms,” which are usually invisible to the naked eye; 20 nanometers: smallest virus - 3-4 um, largest - protozoans
2
Q
Microbes
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General term encompassing microorganisms and viruses; diverse in terms of their appearance, metabolism, physiology, reproduction, and genetics. Ex. bacteria, viruses, protist, fungi, helminthes (larva stages - parasitic worms)
3
Q
Leeuwenhoek (1632-1723)
A
- Inventor of the first microscope, which could magnify objects up to 300X
- First to use microscopes to observe microorganisms in pond water (1674), which he called “animacules”
- Created detailed descriptions of his findings (pond water, plants, insects, tooth scrapings, etc.) over the next 50 years
- Considered to be the “father of microbiology”
4
Q
Robert Hooke
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Fist to describe “cellulae” (small rooms) in cork in 1665, which led to the formulation of the cell theory by others
5
Q
Matthias Schleiden and Theodor Schwann
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Independently published statements that “cells are the basic organizational unit of all living things” - The Cell Theory (1800s)
6
Q
Spontaneous Generation
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The discredited belief that organisms could arise from non-living matter (worms on meat/rats from hay)
7
Q
Biogenesis
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All living cells arise from other pre-existing living cells
8
Q
Science
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An organized body of knowledge about the natural world
9
Q
Scientific Method
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A series of steps used to gain information about the natural world:
- Make an observation/identify a problem
- Gather information about observation/problem
- Formulate a hypothesis (educated guess)
- Conduct a controlled experiment: contol group, experimental group, collect data
- Conclusion: does your data support or refute the hypothesis
- Peer review
10
Q
The Progression of Scientific Ideas
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- Ideal hypothesis is generated
- Experimentation: hypothesis confirmed or rejected
- Peer review/Publication
- If published, scientific community conducts further experimentation
- If experimental data is consistent and reliable then, with time, the original hypothesis becomes a theory
- Consistently supported theories, over long periods of time, can be elevated to scientific law or a constant fact of nature
11
Q
Francisco Redi
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In 1668, he covered rotting meat with fine gauze, showing that maggots developed only in meat that flies could reach to lay eggs; spontaneous generation would not be refuted for another 200 years because many insisted that only spontaneous generation of microorganisms was disproved
12
Q
Needham’s Hypothesis, Experiment, and Conclusion
A
- He boiled chicken broth, put it in a flask, and sealed it
- If microbes grew, then it could only be because of spontaneous generation
- Microbes grew, but we now know this was because the flask was not sterilized before adding the broth
13
Q
Spallanzani’s Hypothesis, Experiment, and Conclusion
A
- He put broth in a flask, boiled it, and sealed it creating a vacuum (no air)
- No microbes in the cooled broth
- Critics said he didn’t disprove spontaneous generation, only that it required air
14
Q
Louis Pasteur’s Experiments
A
- Argued against spontaneous generation; allowed the free passage of air, but prevented the entry of microbes
- Boiled meat broth in a flask which sterilized it; swan neck flask created a seal with water and bacteria
- No microbes developed until flask was tilted so some broth flowed into the curved neck
- Gravity had caused microbes to settle at the low point of the neck, never reaching the base until washed in with the broth
- Could not be replicated by other scientists who used vegetable broth which contains many endospores; original experiment used meat broth (luck) which contains few endospores
15
Q
John Tyndall
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Explained the conflicting results of Pasteur’s experiments, and proved him correct; He concluded that some microorganisms exist in two forms:
- a cell form that is easily killed by boiling
- a cell form that is heat resistant: endospores
16
Q
3 Things Proved by Pasteur’s Experiments
A
- No living things arise by spontaneous generation
- Microbes are everywhere (even in air and dust)
- The growth of microbes causes dead plant and animal tissue to decompose and food to spoil (led him to develop the technique of pasteurization which kept wine from spoiling)
*Also contributed to the development of vaccines
17
Q
Germ Theory of Disease (late 1800s)
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Microbes cause disease, and specific microbes cause specific diseases; previously thought to be caused by “bad air” or linked to superstitions or religion (punishment)
18
Q
Ignaz Semmelweis (1850)
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- Noted that the rate of childbirth infections were greater at teaching clinics than when staffed by midwives
- Doctors went from mother to mother - microbes from infected patients could spread to other patients
- Midwives only worked with one patient
19
Q
Joseph Lister
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- Believed pus around wounds was caused by microorganisms and that if they were killed the wounds might heal faster
- Dressed wounds in phenol soaked cloths, reducing the rate of infection and speeding up the healing process
- Proposed and practiced the idea of antiseptic surgery (sprayed phenol of the patients)
- Phenol is not only toxic to most microorganisms, but humans as well (powerful carcinogenic); no longer used as an antiseptic
20
Q
Robert Koch (late 1870s)
A
- Studied anthrax: disease of cattle/sheep but also in humans
- Observed that microbes were present in all blood samples of infected animals
- Isolated and cultivated these microbes (Bacillus anthracis)
- Injected healthy animal with cultured bacteria and it became infected; blood sample showed same microbes
- Proved that particular microbes cause particular diseases
21
Q
Koch’s 4 Postulates Concerning Disease and Microorganisms
A
- The suspect agent must be present in every individual with the disease
- The suspect agent must be isolated and grown in pure culture
- The pure culture must cause the disease when injected into a healthy, experimental animal
- The suspect agent must be re-isolated from the experimental animal and re-identified in pure culture (eliminates coincidence)
22
Q
Free-Living Organisms
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An organism that is not directly dependent on another organism for survival
23
Q
Autotrophs
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Organisms that:
- Use inorganic molecules or photons (light particles) to create cellular energy (ATP)
- Use CO2 as their principle source of carbon atoms to create new organic molecules necessary for maintaining their life
24
Q
Photoautotrophs
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Use light energy to create ATP, and CO2 for their carbon source
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Chemoautotrophs
Use inorganic molecules (e.g. hydrogen sulfide gas) to create ATP and CO2 as their carbon source
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Heterotrohps
Organisms that:
- Use organic molecules from other organisms to create cellular energy (ATP)
- Use organic molecules in other organisms to create new organic molecules necessary for maintaining their life
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Decomposers
Organisms that use simple organic molecules from dead organisms:
- Use organic molecules from dead molecules to create cellular energy (ATP)
- Use organic molecules form other dead organisms to create new organic molecules necessary for maintaining their life
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Symbiosis
Occurs when two organisms live together
- symbiont: smaller organism
- host: larger organism
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Mutualistic Symbiosis
Both the symbiont and the host benefit from the relationship; acid producing bacteria in the vagina retards growth of yeast while human provides a location, warmth, nutrition, and growth
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Commensalistic Symbiosis
The symbiont receives a benefit from the relationship but does not harm the host
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Parasitic Symbiosis
The symbiont benefits by the relationship but the host is harmed by it
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Exotic Parasites
A pathogen not typically found in the human body, but can invade and cause harm; most flu and cold viruses are not usually found in the human body, they must be introduced by a host
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Opportunistic (Endemic) Parasites
Pathogens that are normal residents of the human body, but only inflict harm to the host when its immunity is weakened; streptococcus pneumonia
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Taxonomy
The classification and identification of organisms
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Classification
The orderly arrangement of organisms into groups that have similar characteristics; all schemes are constantly under review and are subject to change
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Kingdom
The broadest classification of organisms; species in the classification level can be very different
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Questions Determining an Organisms Kingdom Classification
- How many cells does the organism have? Unicellular or Multicellular
- Does the cell(s) have a nucleus? Prokaryotic or Eukaryotic
- How does the organism get its energy and nutrients? Autotroph or Heterotroph
- Cell wall composition? Cellulose, Peptidoglycan, or Chitin
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Kingdom Monera/Prokaryotes
- Prokaryotic
- Unicellular
- Chemoautotrophic or photoautotrophic or heterotrophic (decomposers, parasites, commensalistic, mutualistic)
- Cell wall made from peptidoglycan in true bacteria
- Ex: bacteria*, blue-green algae*, archeabacteria*
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Kingdom Protist
- Eukaryotic
- Unicellular
- Photoautotrophic and/or heterotrophic
- No cell walls
- Ex: Amoebas*, Paramecium*
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Kingdom Fungi
- Eukaryotic
- Most are multicellular, but some are unicellular (yeast)
- heterotrophic by absorption (strictly decomposers), secrete powerful enzymes that break down matter
- Cell walls made from chitin
- Ex: yeast*, mold*, mushrooms
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Plant Kingdom
- Eukaryotic
- Multicellular
- Photoautotrophic: use photosynthesis to produce energy
- Cell walls made from cellulose
- Ex: mosses, ferns, conifers, flowering plants
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Animal Kingdom
- Eukaryotic
- Multicellular
- Heterotrophic by consumption and digestion
- No cell walls
- Ex: coral, sponges, insects, reptiles, birds, mammals
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Carolus Linnaeus
In 1753, recommended the use of binomial nomenclature for the scientific naming of organisms; would reduce confusion in the scientific community; name would consist of two Latin words (dead language): genus name (always capitalized) and species name (never capitalized) which are either italicized or underlined; usually descriptive, honorary, or both
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Strains (Varieties)
Isolated sub-populations of bacteria that are of the same species but have slightly different characteristics
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Phylogenetic Tree
A branching diagram showing the inferred evolutionary relationship among organisms based upon similarities and differences in their physical and/or genetic characteristics
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Differences Between Domain Bacteria and Domain Archaea
- Bacteria and Archaea are as genetically different as Bacteria and Eukarya
- In Bacteria, the cell wall is made of peptidoglycan; Archaea have cell walls that are not made of peptidoglycan, composition varies greatly
- Archaea can thrive in extreme environments: high salinity (10x ocean water), high or low temperatures (105' C, 0' C)
- Archaea species rarely, if ever, cause disease
47
Infectious Agents
An agent capable of causing an infection:
- Capable of self-replications (some form of reproduction)
- Free-living include bacteria, algae, fungi, protozoa, helminthes (larval stages)
- Non-living include viruses, viroids, and prions
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Virus
- Acellular: not considered prokaryotic or eukaryotic
- A piece of DNA or RNA surrounded by a protective protein layer (capsid); no nucleus of organelles or cell membrane or cytoplasm
- 1/10 to 1/1000 the size of an ordinary bacterial cell
- nonmotile
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Viroid
- A small piece of RNA that is not surrounded by a protein layer
- Plant pathogens; uncertain for animals
- Potato spindle tuber disease
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Prion
- A small self-replicating protein, no RNA or DNA
- Affect the structure of the brain or other neural tissue and all are currently untreatable and universally fatal
- Bovine spongiform encephalopathy ("mad cow disease")/Creutzfeldt-Jakob Disease (CJD)
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Microbe Functions Necessary for Human Life
- Nitrogen Fixation: Bacteria convert nitrogen gas (N2) into a solid form that is usable by plants, then other organisms
- Oxygen gas (O2) production
- Biodegradation: Microorganisms can break down glucose and other organic debris in the process of decomposition, instead of it accumulating within the environment
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Economic Applications of Microbiology
- Alcohol production; wine, beer, spirits (yeast)
- Food production: vinegar, yogurt, cheese, bread
- Drug production; Insulin, Interferon, ethanol, antibiotics
- Bioremediation: Help clean up the environment; bacteria can often break down toxic or unwanted waste products (oil spills)
- Agricultural: research has led to healthier livestock and disease-free crops
