Chapter 1: The Evolution of Microorganisms and Microbiology Flashcards
Microorganisms
are too small to be seen with the naked
eye and require the use of a → microscope
• They can be either unicellular or
multicellular
Prokaryotes
do not have membrane bound
compartments
Eukaryotes
are compartmentalized with membrane
bound organelles and a nucleus
These cell difference led to the five kingdoms, which was
narrowed down to the three →
Domains
• Bacteria, Archaea, and Eukarya
How we got to the three Domain system:
- Use of the electron microscope to visualize fine
structures of cells - Measurement of biochemical and physiological differences
- Nucleic acid analysis (especially rRNA!)
Domain Bacteria
• Single-celled → prokaryotes
• Have a cell wall that contains → peptidoglycan
• Members of the microbiome, which is found in and on the human body
• Help develop the immune system
• Digest food and produce vitamins in the large intestine
• Some do make you sick and cause → disease
microbiome
the microorganisms in a particular environment (including the body or a part of the body)
Domain Archaea
• Are also single-celled
prokaryotes:
• But…they are set apart from
bacteria by their ribosomal
RNA (rRNA), cell membranes,
and cell walls
• Found in extreme
environments with high
temperatures or high salt
Domain Eukarya
• Includes plants, animals, and
microorganisms like protists and fungi
Protists
are unicellular and are found in
two groups algae and protozoa
Algae are →
photosynthetic
Protozoa are
motile and have an
animal-like → metabolism
Fungi are very ___
diverse, they range from unicellular
yeasts to multicellular molds and mushrooms
Can form health associations with some organisms
and cause disease in others
How is the metabolism of a fungi beneficial?
they are very beneficial in
decomposition, the food industry, and medicines like penicillin
Acellular Infectious Agents include:
Viruses, viroids, satellites, and prions
Viruses
• Acellular entity that must invade a host cell
in order to → reproduce
• Consist of nucleic acid and a protein coat
• Cause disease in every known organism on
the planet
Viroids
• Consist of only → RNA
• Cause plant diseases
Satellites (“helper virus”)
• Consist of a nucleic acid inside of a protein shell
• Coinfect with viruses to complete their life cycle
Prions
• Made of only → protein
• Cause → encephalopathy
• “Mad cow disease” in cattle and scrapie in sheep
• Can be transmitted to Humans through infected meat
or medical equipment
Theories of the Origin of Life
• Earth is estimated to be 4.5-4.6 billion years old
• Life would have been unsupported for the first 100 million years because of harsh conditions
• Meteorite strikes → decreased
• Water appeared along with an
→atmosphere
• Life was present on Earth 3.5-3.8 billion years ago based on → molecular fossils
• It would have had:
• an orderly → structure
• the ability to obtain and use energy
• and → reproduce
Probiont
were early cells
• Would have consisted of a single molecule that could do
cellular work and replicate
• RNA can be ____ and act as ____ by forming
bonds between the ____ of proteins
• It can also store, copy, and express ____
• RNA can be catalytic and act as ribozymes by forming bonds between the amino acids of proteins
• It can also store, copy, and express genes
Early cells formed when…
RNA was taken-up by a lipid vesicle called a liposome
Liposome
Lipid vesicles
RNA may have allowed for the formation of
DNA, which is similar structurally with a more stable → structure
and
ATP may have also formed from RNA since it is a ribonucleotide
The evolution of metabolism is based on
• Earth’s atmosphere, which would have been
oxygen free and hot when life was forming
• Modern Archaea would be a descended
based on their ability to metabolize in harsh
conditions
Atmospheric oxygen would have been formed by the evolution of ______ about 2.7 billion years ago
photosynthesis
• Modern cyanobacteria would have descended from
these organisms
The production of oxygen allowed for the evolution of
aerobic respiration
Bacteria that use aerobic respiration became → mitochondria
Evolution of the Three Domains
• Last universal common ancestor (LUCA) is the most recent organism that all three Domains → evolved
• Bacteria branch off LUCA, Archaea and Eukarya evolved independently from bacteria
• Archaea and Eukarya diverged from one another to
form separate Domains
IN OTHER WORDS….
—-oldest
LUCA 1ST
BACTERIA 2ND
ARCHAEA AND EUKARYA SPLIT TO BE 3RD AND 4TH
—-newest
Endosymbiotic hypothesis
• Endosymbiotic hypothesis – energy related organelles became part of eukaryotic cells through endosymbiosis
endosymbiosis
Once independent prokaryotic microbes evolved to live inside of early eukaryotes
Bacteria that use aerobic respiration became →
mitochondria
Photosynthetic cyanobacteria became →
chloroplasts
Both organelles, mitochondria and chloroplasts, contain
(Tina’s note: I think mitochondria and chloroplast are the organelles she was referring to, but if you want to see for yourself its on slide 29)
• Bacteria DNA and → ribosomes
• Peptidoglycan is found between the membranes in
some organisms
For anaerobic bacteria that produce hydrogen gas of CO2 became ______
hydrogenosomes
• Found in fermenting protists to make ATP
Mutations
have been key to the evolution of cellular
microbes
• The best mutations allow for better reproduction or
survival and are passed on to future
generations
• This allowed for the formation of new genes and new species
Genetic diversity is best in _____
sexually reproducing organisms
Bacteria and archaea
• They can share genetic material through → horizontal gene transfer
• DNA is transferred from a donor to recipient
• Causes antibiotic resistance, new
virulence genes, and new metabolic
abilities
Microbial Taxonomy
the rank-based classification, of bacteria
Microbes are named using ________
binomial nomenclature system
• The name is Latin and italicized
• First part is the genus, which is → capitalized
• Second part is the species, which is → lowercase
• Ex. Yersinia pestis
• Can be abbreviated to → Y. pestis
Microbiology came to light with the invention to the →
microscope
• From there, pure culture was used to growth bacteria in
isolation for study purposes
• Today we use molecular and genomic study
Robert Hooke
published the first drawings of microorganisms in his book “Micrographia”
• Drew the fungus, Mucor
• Discussed a prototype for microscopes
Antony van Leeuwenhoek
most likely built the prototype that was published by Hooke
• Microscope provided dark-field
illumination of liquid specimens
• Viewed bacteria and Protists
spontaneous generation
• The theory of spontaneous generation was a belief that
living organisms can develop from nonliving matter
Who challenged the theory of Spontaneous Generation?
Francesco Redi
• Preformed experiments using rotting meat, which was
believed to form maggots spontaneously
How did Redi perform his experiment?
• Redi showed by covering or uncovering meat in jars that maggots were formed by flies, and they were not spontaneously generated
Who ended the debate over spontaneous
generation?
Louise Pasture
How did Louise Pasture ended the debate over spontaneous generation?
• He filtered air through cotton and found “plant-like” spores were removed from the air
• When put in sterile broth, microbial growth occurred
• To prove that the air had no
spontaneous generation ability be
created a swan-neck flask
• Nutrient solution was added into
the flask and→ boiled
• Air was exposed to the broth,
but dust and germs could not
get around the neck
• Growth only occurred is the neck
of the flask was→ broken
John Tyndall
• Was able to show that dust carries → germs
• Showed that broth remained sterile even if it is exposed to air
• Discovered the existence of heat-resistant bacteria
Ferdinand Cohn
showed that those heat-resistant
bacteria formed → endospores
There was a time when disease was thought to be caused by the supernatural, poisonous air, or body imbalance of the four humors _____, ______, ______, and ______.
blood, phlegm, yellow bile, and black
bile
Germ theory of disease states that
microorganisms cause disease
How did Pasture use the Germ Theory of Disease to help with the French wine industry?
• Showed that contaminating bacteria was spoiling the wine
• Created pasteurization, which killed spoiling microbes but did not harm the wine
pasteurization
kills spoiling microbes without harming the microbe’s host (milk, wine, etc.)
Robert Koch
was able to show relationships between specific microorganisms and a disease
• Koch’s Postulates
• Worked with Guinea Pigs and
Pure culture
Steps of Koch’s Postulates
- The microorganism must be present in every case of the disease but absent from health organisms
- The suspected microorganisms must be isolated and grown in a pure culture.
- The same disease must result when the isolates microorganism is inoculated into a healthy host
4.The same microorganisms must be isolated again from the diseased host.
Koch’s Postulates are still used, but they have some downsides. What are these current inconveniences?
• Koch’s postulates are still used but they are not always feasible
• Some causative agents, like Mycobacterium leprae, cannot be growth in pure culture
• There is no animal model available to test the
postulates
What is the most common method of Koch’s
postulates?
Genetic analysis, study genes associated with virulence.
Pasture and Pierre Roux found that if you incubate cultures for long periods of time, they will not be able to
cause disease
• Pasture made an attenuated vaccine against → rabies
• It was given to a 9-year-old boy that was bitten by a rabid dog
Edward Jenner
created a smallpox vaccine with material
from cowpox lesions
