CH. 1 Microbial Life Flashcards
How do you define a microbe? What are the exceptions to this definition?
A microbe is defined as a living organism that requires a microscope to be seen.
Some exceptions to these definitions are super-size microbial cells, microbial communities, and viruses
Some multicellular organisms (ex. tardigrade) require a microscope to see but are NOT considered microbes
What were van Leeuwenhoek’s & Hooke’s contributions to microscopy?
Van Leeuwenhoek was the first to observed microbes using a MICROscope
Hooke viewed MACROscopic life while publishing drawings of it
Who are the microbes? Briefly describe and characterize the different members here.
CELLULAR ENTITIES
Prokaryotes (lacking nucleus and organelles)
- Archaea (thermophiles, methanogens, and halophiles - extreme temperature environments)
- Bacteria
Eukaryotes (has nucleus and organelles)
- Fungi
- Protists
ACELLULAR ENTITIES (mainly composed of protein, RNA, and nucleic acid)
-Viruses (requires a host cell to replicate)
-Viroids
-Prions
When did microbes originate? Who would have been the first microbes on Earth? What kind of metabolism would they have had?
Microbes first originated about 3.8 - 4 billion years ago
The first microbes that have been on Earth are prokaryotes that had a carbon metabolism
When did eukaryotic cells evolve? (describe the endosymbiont theory of eukaryote evolution)
States that eukaryotic cells could possibly evolve from pre-eukaryotic cells merging with bacteria to form a composite cell
Evidence:
Mitochondria & chloroplasts possess DNA w/ homology to bacteria, ribosomes & tRNA, and organelles can duplicate
What is meant by microbial endosymbiosis? Describe examples of microbial endosymbioses.
Microbial endosymbiosis is the intimate association between the host and its endosymbiont(s) growing within it
Ex. human microbiome and bacteria-plant endosymbiosis
What are the six major groups studied by microbiologists? How do these latter groups fit into the three domains of life and into kingdoms? Which are prokaryotic and eukaryotic?
6 Major Groups:
-Bacteria (prokaryotes)
-Archaea (prokaryotes)
-Fungi (eukaryotes)
-Protozoa (eukaryotes)
-Algae (eukaryotes)
-Viruses
Prokaryotes either belonged in the domains Bacteria or Archaea. Eukaryotes belonged in Eukarya
What are some of the basic differences between
prokaryotic and eukaryotic cells? How were the domains discovered?
Prokaryotic cells lack nuclei and organelles, reproduce asexually, and have diverse metabolisms. Eukaryotic cells have a nucleus, and organelles, and reproduce asexually or sexually.
The three domains were established by Carl Woese who used the 16S ribosomal RNA gene sequence as a “molecular clock” to measure the time since the divergence of two species which led to the discovery of archaea
How do archaea differ from bacteria and
eukaryotes?
Archaea differs from bacteria and eukaryotes by having some species grow in extreme environments that bacteria or eukaryotes cannot grow in
What is metagenomics and how has this advanced what we know about microbes?
Metagenomics is the collection of genetic sequences taken directly from the environment
This has advanced the knowledge about microbes by allowing for the collecting of information regarding the genetics of unculturable microbes
What is spontaneous generation?
Living organisms could arise spontaneously without parental organisms (life from non-life; abiogenesis)
What was Louis Pasteur’s contribution to disproving the theory of spontaneous generation?
Pasteur boiled a meat broth with a flask that had curved long neck to prevent microbes from falling into the broth… this showed that no bacteria was present after letting the broth sit. However, he later cut the flask neck and also tilt the flask to let the broth sit near the opening of the neck which shows bacteria was present in those two findings
It was shown that living organisms that were found in the broth came from outside (ex. spores on dust) which disproved the theory of spontaneous generation
What did John Tyndall discover?
John Tyndall found opposite results when duplicating Pasteur’s experiment:
- Found that the broth sometimes gave rise to microbes no matter how long it was sterilized for due to endospores (heat-resistant microbes)
Describe Pasteur’s work with fermentation. What was the significance of this?
Discovered that yeast carry out the fermentation (yeast producing alcohol) without oxygen
Fermentation: Microbes gain energy by converting sugar into alcohol
What is the principle of immunization? What is vaccination and how does this relate to immunization? What were Edward Jenner’s and Pasteur’s contributions to this field?
The principle of immunization is the process by which a person is made resistant to a particular disease by the administration of a vaccine
Vaccination is the exposure of an individual to a weakened version of a microbe/microbial antigen to provoke immunity and prevent the development of disease upon exposure
Edward Jenner and Pasteur contributed to this by Jenner usage of cowpox to vaccinate (less virulent than smallpox) while Pasteur made attenuated vaccines for fowl cholera and rabies
