Chapter 28 Flashcards
The Italian physician who suggested that disease was caused by unseen organisms in 1546
Girolamo Fracatoro
The first to observe and accurately describe microbial life
Anton van Leeuwenhoek
French microbiologist who refuted the controversy over spontaneous generation
Louis Pasteur
German physician who studied anthrax and was able to determine the causative agent
Robert Koch
Koch’s postulates
- The microorganism must be present in ____ and absent in ____
- The causative agent must be ____
- The same disease must result when ___
- The same microorganisms must be ____
- must be present in every case of the disease and absent in healthy individuals
- Isolated and grown in a pure culture
- When the cultured microorganism is used to infect a healthy host
- Isolated again from the diseased host
The oldest, structurally simplest, and most abundant forms of life. The only organisms with prokaryotic cellular organization.
Archaea and bacteria
Unicellularity
Prokaryotes are fundamentally single celled
In their natural environments most bacteria appear to be capable of forming a complex community of different species called a ___
Biofilm
Cell size
Most prokaryotic cells are only 1 micrometer or less in diameter, they are very small
Nucleoid
Prokaryotes lack a membrane bound nucleus and instead usually have a singular circular chromosome
Flagella
Prokaryotic flagella are composed of a single fiber. Bacterial flagella are also more rigid and spin like a propellar
Metabolic diversity
Prokaryotes are the only chemolithoautotrophic organisms meaning they use inorganic molecules to make carbohydrates
Name the four key areas that Archaea and Bacteria differ
Plasma membranes
Cell wall
DNA replication
Gene expression
Archaen plasma membrane lipids are composed of _____ linked to ______ by ether linkages, not the ester linkages seen in bacteria and eukaryotes
glycerol linked to hydrocarbon chains by ether linkages
The cell wall of bacteria are constructed minimally of ___ which is formed from carbohydrate polymers linked together
Peptidoglycan
The cell walls of archaea lack peptidoglycan although some have ____ which is similar in structure and function
Pseudomurein
Archael initiation of DNA replication is similar to that of ___
eukaryotes
In terms of gene expression, archaea may have more than one ____. Some of the translation machinery is also more similar to that of eukaryotes
RNA polymerase
Molecular approaches to classification of Prokaryotes
- the analysis of ______ of key proteins
- The analysis of ____ by establishing a percent of G and C
- ______ the mixing of single-stranded DNA from two species and determining the amount of base pairing
- ___ and ____ sequencing, especially looking at ribosomal RNA
- Whole ____ sequencing
- the amino acid sequence of key proteins
- nucleic acid-base sequences by establishing the percent of G and C
- Nucleic acid hybridization
- gene and RNA
- genome
Developed the three-domain system of phylogeny
Carl Woese
The study of prokaryotic organisms was first made possible by
microscopes
Early microbiology grew from the study of
disease-causing agents
Bacteria and archaea are clearly different based on both ___ and ____
structure and metabolism
Classification of prokaryotes had been based on ___ and it has now been aided by the use of ____
physical characteristics
DNA analysis
A vast number of prokaryotes have not been studied because
they cannot be cultured
Most prokaryotes exhibit one of the three basic shapes
bacilli, cocci, and spirals
one or several of these structures may be found on the outer surface of many prokaryotes, used to propel the organisms in a fluid environment
Flagella
Minimally the prokaryotic cell wall consists of ____ which is important for structure because it maintains the shape of the cell and prevents it from swelling and rupturing in hypotonic solutions
peptidoglycan
Have a thick layer of peptidoglycan and stain a purple color
Gram-positive
Contain less peptidoglycan and do not retain the purple dye. Can be stained with a red counter stain and then appear dark pink
Gram negative
In some bacteria and archaea an additional protein layer forms a rigid paracrystalline surface called a _____. Often involves adhesion to surfaces or protections
S-layer
In some bacteria an additional gelatinous layer called a ___ surrounds the other wall layers. Enables the cell to adhere to surfaces and other cells and to evade an immune response.
Capsule
Other hairlike structures that occur on the cells of some gram-negative prokaryotes, they are more important in adhesion than in movement, they also play a role in the exchange of genetic information
pili
Some prokaryotes are able to form a thick wall around their genome and a small portion of cytoplasm when they are exposed to environmental stress, When conditions improve they can germinate and return to normal cell division
Endospore
Many prokaryotes possess invaginated regions of the plasma membrane that function in respiration or photosynthesis
Internal membranes
Prokaryotes lack nuclei and generally do not possess linear chromosomes. Instead their genes are encoded in a single double stranded ring of DNA that is highly condensed to form a visible region of the cell called the
Nucleoid region
Prokaryotic __ are smaller than those of eukaryotes and differ in protein and RNA content
ribosomes
Horizontal gene transfer that occurs when genes move from one cell to another
conjugation
Conjugation performed by viruses
transduction
Some plasmids can be trasnferred from one cell to another via conjugation. The best known plasmid capable of transfer is
F plasmid or fertility factor
Acts as an independent genetic entity that nevertheless depends on the cell for replicaiton
Plasmid
When the F plasmid is integrated into the chromosome, the cell is called an
Hfr cell (high frequency of recombination)
Genes close to the origin of transfer are transferred __ and this far from the origin are transferred ___
earlier
later
Can be used to determine if new isolated mutations are alleles of known genes
Merodiploids
The uptake of DNA directly from the environment
transformation
Some conjugative plasmids pick up antibiotic resistance genes becoming
R plasmids
DNA can be exchanged by conduction via ___ by transduction via ___ and by transformation through ___
plasmids
viruses
the direct uptake of DNA from the environment
The different forms of DNA exchange can be used to
map genes
Variation in prokaryotes also arises through
mutation
Extensive use of antibiotics has led to selection for
resistant organisms
Many bacteria carry out photosynthesis, using the energy of sunlight to build organic molecules from carbon dioxide. These are called ____
Photoautotrophs
Some prokaryotes obtain energy by oxidizing inorganic substances and are called ____
chemolithoautotrophs
ex: nitrifiers
Purple and green nonsulfur bacteria use light as a source of energy but obtain carbon from organic molecules produced by other organisms and are called
Photoheterotrophs
The majority of prokaryotes obtain both carbon atoms and energy from organic molecules and are called
Chemoheterotrophs
Some bacteria can attack other cells directly. The invading pathogen Yersinia (bubonic plague) secretes proteins that contain a special signal that allows them to pass through the bacterium’s double membrane like a syringe and into the cytoplasm of host cells. This system is known as
Type III system
Almost every kind of plant is susceptible to one or more kinds of bacterial disease including ___,____, and ____
blights
soft rots
wilts
One of the oldest known infections. Afflicts the respiratory system and thwarts the immune system. Easily transmitted through the air
Tuberculosis
What is the treatment for TB?
Multiple expensive ABX for 6-12 months
Tooth decay is caused by the bacteria present in plaque
S. sobrinus and S. mutans
Many STD’s are caused by bacteria three important examples are
gonorrhea
syphilis
chlamydia
Prokaryotes and fungi that carry out the decomposition portion of chemical cycles releasing a dead organism’s atoms to the environment
Decomposers
Prokaryotes that return elements from inorganic forms to organic forms that heterotrophic organisms can use
Fixation
Plants, algae, and photosynthetic prokaryotes produce organic compounds from CO2. Are responsible for the oxygen in the earth’s atmosphere
Carbon fixers
A few species of prokaryotes are able to reduce nitrogen gas in the air into ammonia which is used to build amino acids
Nitrogen fixers
In aquatic environments nitrogen fixation is carried out by ____. In soil it is carried out by ____
cyanobacteria/heterocysts
bacteria that live in the roots of plants
Many bacteria live within the digestive tracts of animals providing nutrients to their hosts
mutualism
Many bacteria inhabit outer surfaces of other animals ad plants without doing damage
Commensalism
The use of organisms to remove pollutants from water, air, and soil
Ex: breakdown of sewage by bacteria in sewage treatment plants, methane produced is harnessed for heat energy
bioremediation
The addition of nutrients to encourage the growth of naturally occurring microbes that can degrade crude oil sills
Biostimulation
