Lecture 8 Flashcards
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All organisms can be grouped into a series of subdivisions that make up the what?
taxonomic hierarchy
One kind of microorganism, a subdivision of a genus.
Species
Consists of species that differ from each other in certain ways but are related by descent
Genus
All related genera make up a
Family
A group of similar families constitutes an
Order
A group of similar orders makes up a
Class
Related classes make up a
Phylum (PLURAL PHYLA)
Related phyla make up a
Kingdom or Domain
has been described qualitatively e.g. as a collection of genetically similar populations which are capable of genetic interchange, and or interbreeding, and which are evolving together in a common pattern
A species
A collection of cells derived from a single cell
Strain
Strains are identified by numbers, letters, or names that follow the ___________
specific epithet e.g. E.coli OP59.
True of False;
Sometimes the members of a bacterial species are essentially indistinguishable from other species of the same genus morphologically, and further testing is required to identify them.
True
The 18th century Swedish Botanist Carolus Linnaeus is credited with founding the science of taxonomy. He originated ________ _________ the system that is still used today to name all living things.
binomial nomenclature
In the binominal, or “two name” system the first name designates the ________ of an organism, and it’s first letter is _________
genus (plural: genera). Capitalized
The second name is the ___________. Is it capitalized or not? Derived from the name of the person who discovered it.
specific epithet, Capitlalized
The name of an organism often tells something about it, such as
- its shape,
- where is found,
- what nutrients it uses,
- who discovered it,
- or what disease it causes
Growth Dependent Identification methods
Identification of a clinical isolate can frequently be made using a variety of growth dependent assays. On the basis of growth characteristics in primary isolation media, an unknown pathogen is usually sub-cultured on diagnostically useful culture media
Sugar fermentation test: Fermentation of sugars is measured by incorporating what with what reaction?
pH indicator dyes that change color on acidification.
Triple Sugar Iron Agar (diagnostic test for enteric bacteria)
Hydrogen sulfide production is indicated following growth in a medium containing _______ _______. If sulfide is produced,______ ______complexes with H2S to form ______ precipitate of iron sulfide.
ferric iron, ferric iron, black
Production of hydrogen gas and/or carbon dioxide during sugar fermentation is assayed by observing what?
gas production either in gas collection vials or in agar
How many carbons and carboxylic groups does citric acid have?
6 carbons, 3 carboxylic groups
Utilization of citric acid is accompanied by a increase in what?
pH
A specific dye incorporated into the citric acid test medium changes color as conditions become what?
alkaline.
In the gelatin liquefaction test what hydrolyzes the gelatin to destroy the gel?
Proteases
What is the gelatin liquefaction test used to identify?
Serratia, Pseudomonas, Flavobacterium, Clostridium
In the coagulase test; enzymes cause the clotting of blood. 2 examples of these are
S. aureus, and S. epidermidis
Voges-Proskauer test:
Acetoin produced from sugar fermentation. Used to separate what 2 things from what?
Klebsiella and Enterobacter from Esherichia
When a microorganism enters the body of the other organisms stimulate it to form antibodies this is called what?
antigenic
Antibodies are __________that circulate in the blood and combine in a highly specific way with the _______ that caused their production.
proteins, bacteria
For example, the immune system of a rabbit injected with killed typhoid bacteria (antigens) responds by producing antibodies against typhoid bacteria. Solutions of such antibodies used in the identification of many medically important microorganisms are commercially available; such a solution is called an ____________.
antiserum.
ELISA stands for
Enzyme-linked immunosorbent assay (ELISA):
Western blotting is used to identify what?
bacterial antigens in a patient’s serum.
HIV and Lyme disease is often diagnosed using this technique
Western blotting
In Western blotting proteins in the patient’s serum are separated by a process called _____________.
electrophoresis
Kirby-Bauer method and testing cultures for antimicrobial sensitivity are examples of what?
Antibiosis
Analysis of profiles of one or more proteins of different bacterial species provides a reasonable basis for comparisons. Protein profiles are produced by what method?
Polyacrylamide gel electrophoresis (PAGE) method.
PAGE method separates proteins on the basis of what?
molecular size.
List 3 chemical methods in identifying microorganisms
Protein profiles and amino acid sequences, Fatty acid profiles, and flow cytometry
A classification technique that has come into wide use among taxonomists is the determination of an organism’s DNA Base Composition. This base composition is usually expressed as the percentage of what and what?
guanine plus cytosine (G+C).
A method that is currently being used to determine the diversity of organisms and the phylogenetic relationships among them.
rRNA sequencing
A method that can be used to increase the amount of microbial DNA levels that can be tested by gel electrophoresis.
The Polymerase Chain Reaction (PCR)
The procedure measures the ability of DNA strands from one organism to hybridize with the DNA strands of other organism.
Nucleic acid hybridization
A method that makes it possible to quickly sequence entire genomes or detect a pathogen in a host by identifying a gene that is unique to that pathogen.
DNA chip
A test for determining which phages a bacterium is susceptible to Bacteriophage infections are highly specialised, in that they usually infect only members of a particular species, or even particular strains within a species.
Phage typing
Bacteriophages are specific to what 3 things?
Species, genus, family
What are 2 types of keys used in the identification of microorganisms?
Dichotomous keys, and cladograms.
In this key, identification is based on successive questions; each question has two possible answers. After answering one question, the investigator is directed to another question until an organism is identified.
Dichotomous key
They are maps that show evolutionary relationships among organisms
cladograms
What method is primarily used to make cladograms for microorganisms.
rRNA sequencing
Organism identification method based on the idea that increasing the number of characteristics of organisms that we observe increases the accuracy with which we can detect similarities among them.
numerical taxonomy
Use of more than one identification technique is called ________ __________ which enables the establishment of more reliable identification result for a tested bacterium.
polyphasic taxonomy
When groups of closely related organisms are identified, it is presumed that they probably had a common ancestor and that small differences among them have arisen by ________ _________.
divergent evolution
A phylogenetic category which currently includes all those Prokaryotic microorganisms not classified in the Archaebacteria
Eubacteria
Within the Eubacteria, an early divergence gave rise to two important subgroups
Gram negative, Gram positive
A collection of strains that share many common features and differ significantly from other strains.
a species (for bacteria)
A bacterial _______ consists of descendants of a single isolation in pure culture.
strain
Bacteriologists designate one strain of a species as the ______ ______. Usually this is the first strain described.
type strain
The accepted reference on the identification of bacteria is commonly referred to as _______ ________
Bergey’s Manual.
