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
Probiotics
Live microorganisms that provide a health benefit
Bioremediation
Process that uses microorganisms to degrade harmful chemicals
Biotechnology
The use of microbiological and biochemical techniques to solve practical problems and produce valuable results
Why are microorganisms good model organisms to study?
- They have the same fundamental metabolic and genetic properties as higher life forms.
- Bacteria can be used to obtain results very quickly because they grow rapidly and form billions of cells per kilometer on simple , inexpensive growth media.
Pathogens
Disease causing microbe
Chytridiomycosis
A fungal disease decimating frog populations around the world.
What is argued as the most significant triumph with respect to disease control?
Eradication of small pox
Emerging infectious disease (EID)
An infectious disease that has become more common in the last several decades
Living organisms are composed of cells with one of two basic structures-what are they?
Prokaryotic
Eukaryotic
What does prokaryotic mean?
Pro- “Prior to” Karyote- “nucleus”
Prokaryotic cells
Do not have a membrane bound nucleus.
Genetic material is located in a region called the nucleoid.
Where is the genetic material located in a prokaryotic cell?
The genetic material is located in a region called the nucleoid.
Eukaryotic cells
Have a variety of membrane bound organelles.
Genetic material is contained within a membrane bound nucleus
Where is the genetic material in a eukaryotic cell contained?
Nucleus
What are 3 big differences between prokaryotes and eukaryotes?
- Location of genetic material
Prokaryotes have genetic material in nucleoid. Eukaryotes have genetic material in nucleus. - Prokaryotes have no membrane bound organelles, eukaryotes do.
- Eukaryotes are typically much larger and more complex than prokaryotic cells.
Eukaryotes
Organisms that consist of one or more eukaryotic cells
Prokaryotes
Organisms that are composed of a prokaryotic cell
Two categories prokaryotes fall into:
- Bacteria
- Archaea
All living things are classified into what 3 domains?
- Bacteria
- Eukaryotes
- Archaea
Carl Linnaeus
Invented the binomial (two name) system of nomenclature
Explain how binomial nomenclature works.
First part of the name indicates first letter always capitalized)
The second part indicates the specific epithet r species (and is not capitalized)
Genus
Collection of related species
Species
A group of closely related strains; the basic unit of taxonomy.
Strain
Genetic variant within a species
Bacteria
Single celled prokaryotes
Typically have rigid cell walls with peptidoglycan
Many move using flagella
What do bacteria cell walls have that is unique to them?
Peptidoglycan
Flagella
Filamentous appendages that extend from the cell
What are the common bacterial shapes?
- Coccus
- Rod or bacillus
- Vibrio
- Spirillum
- Spirochete
- Pleomorphic
Coccus
A spherical cell that may be flattened on one end or slightly oval
Rod or bacillus
A cylindrical cell.
Vibrio
A short curved rod.
Spirillum
A curved rod long enough to form spirals.
Spirochete
A long spiral shaped cell with a flexible cell wall and unique mechanisms of motility.
Pleomorphic
Not an actual shape
Refers to bacteria that characteristically vary in their shape
How do bacteria typically multiply?
Binary fission
Binary fission
A process in which one cell enlarges and then divides. This forms two cells each equivalent to the original
Diplococci
Cocci that typically remain as pairs
Clusters,packets,chains
Look up a good definition
How are archaea similar to bacteria? List 5
- Both are single called prokaryotes
- Both multiply by binary fission.
- Similar size, shape appearance
- Move primarily by means of filamentous appendages and have rigid cell walls.
- Both have different energy sources
Differences between Archaea and bacteria:
- Archaeal cell wall does not contain peptidoglycan, bacterial cell wall does.
- Composition and structural organization of appendages the archaeal cells use for motility are different from bacterial flagella.
- Archaea also have characteristic nucleotide sequences in their ribosomal RNA that differ from bacteria
RNA
A molecule involved in protein synthesis
What is an interesting feature of archaea?
Their ability to grow in extreme environments in which most other organisms cannot survive
Types of eukaryotes:
- Fungi
- Algae
- Protozoa
- Helminths (worms)
Algae and Protozoa are…
Protists
Fungi
Heterotrophic eukaryotic organisms containing chitin in the cell wall.
Hyphae
Microscopic filaments of molds
Can branch as well as twist and turn to form a visible mat called a mycelium.
Mycelium
Hyphae that twist and turn to form a visible mat. The mat is mycelium.
Conidia
Reproductive form of mycelium.
Easily become airborne allowing fungi to spread.
Mushroom
Fungi that make macroscopic reproductive structures
What do fungi harvest energy from?
Organic materials
How do fungi harvest energy from organic materials?
They secrete enzymes that degrade the organic material and then take in the nutrients that are released.
Algae
Diverse group of photosynthetic eukaryotes.
Can be single celled or multicelular.
Where does photosynthesis in algae occur?
Chloroplasts
Describe the composition of algae
The cell walls are rigid.
Algae move by flagella, which are structurally more complex then prokaryotic flagella.
Protozoa
Microscopic single celled eukaryotes that live in both aquatic and terrestrial environments.
Describe the composition of protozoa
Do not have a rigid cell wall.
Most are motile and ingest organic material as food sources.
Helminths
Worms that live at the expense of a host.
An important cause of disease in developing countries.
Acellular infectious agents
Are not composed of cells.
What are the acellular infectious agents
Viruses
Viroids
Prions
Viruses
Consist of a nucleic acid packaged within a protein coat.
How do viruses multiply?
To multiply, viruses infect living cells and then use the machinery and nutrients of those cells to replicate.
How do viruses act outside of hosts?
Viruses are inactive outside the hosts.
Obligate intracellular agents
Cannot replicate outside the host
Give an example of an obligate intracellular agent
Viruses
Hosts
Organism in which smaller organisms or viruses live, feed and reproduce
What can viruses do to the cells they replicate?
-kill cells in which they replicate
-can remain in host cell without causing obvious ill effects.
As host cell multiply, they copy the viral genetic info passing it along to their progeny
Viroids
Infectious agent of plants that consist only of RNA.
Are simpler than viruses
Prions
Infectious proteins that cause diseases called spongiform encephalopathies.
Only consist of protein. No DNA or RNA.
Are simply misfolded versions of normal cellular proteins found in the brain.
What happens when misfolded versions of normal cellular proteins come in contact with normal cellular protein?
It causes normal protein to also misfold.
These misfolded versions bind together within the cell to form threadlike structures called fibrils.
What does encephalopathy mean?
Encephalo means “brain”.
Patho means “disease”
Bovine spongiform encephalopathy (BSE)
Most widely recognized prion disease.
Commonly called mad cow disease.
What are prions resistant to?
More resistant to degradation by cellular enzymes than normal counterparts.
Also resistant to the usual sterilization procedures that destroy viruses and bacteria.
