Classification of infectious agents (part 1) Flashcards

1
Q

Taxonomy

A

is the science of classifying organisms

• Shows degree of similarity among organisms

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2
Q

Systematics, or phylogeny

A

is the study of the

evolutionary history of organisms

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3
Q

1735: Linnaeus

A

—kingdoms Plantae and Animalia

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4
Q

1800s

A

Bacteria and fungi put in kingdom Plantae
(Nägeli); Kingdom Protista proposed for bacteria,
protozoa, algae, and fungi (Haeckel)

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5
Q

1937

A

Prokaryote introduced to distinguish cells

without a nucleus

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6
Q

1968 Murray

A

—Kingdom Prokaryotae

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7
Q

• 1969: Whittaker—

A

five-kingdom system

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8
Q

The Three Domains

A
• Developed by Woese in 1978; based on
sequences of nucleotides in rRNA
• Eukarya
• Animals, plants, fungi
• Bacteria
• Archaea
• Methanogens
• Extreme halophiles
• Hyperthermophiles
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9
Q

A Phylogenetic Tree

A
Grouping organisms according to common
properties
• Fossils
• Genomes
Groups of organisms evolved from a common
ancestor
Each species retains some characteristics of
its ancestor
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10
Q

In Bergey’s Manual, name of genus…

A

s at the beginning of each

article

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11
Q

The Taxonomic Hierarchy

A

A series of subdivisions developed by Linnaeus to

classify plants and animals

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12
Q

Eukaryotic species

A

a group of closely related

organisms that breed among themselves

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13
Q

3 domain of life

A

arch,bact eul

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14
Q

how many dif phylums does bacteria have.

A

24

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15
Q

how many different classes does proteobacteria have

A

5 defined by 16s rna

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16
Q

Culture

A

: bacteria grown in laboratory media

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17
Q

Clone

A

population of cells derived from a single parent

cell

18
Q

Strain

A

genetically different cells within a species
• (In biology strain is a low-level taxonomic rank below
the rank of species)

19
Q

Logical steps in classification

A
Collection of data. The bacterial strains that are to be classified
have to be chosen, and they must be examined for a number of
relevant properties (taxonomic characteristics).

• 2. Data must be coded.

• 3. Similarity or resemblance between the strains is calculated. This
yields a table of similarities (similarity matrix) based on the chosen
set of characters.

• 4. Similarities are analyzed for taxonomic structure, to yield the groups
or clusters that are present, and the strains are arranged into phenons
(phenetic groups), which are broadly equated with taxonomic group
(taxa)

• 5. Properties of the phenons can be tabulated and most appropriate
characters (diagnostic characters) can be chosen on which to set up
identification systems that will allow the best identification of additional
strains.

20
Q

Classification of Viruses

A

Not a part of any domain; not composed of cells;

require a host cell

21
Q

Viral species:

A

population of viruses with similar characteristics that occupies a particular
ecological niche

22
Q

New ICTV classification system (2019)

A

New classifciation system - 15 rank
Now classe and phylums are now added
Keep in mind baltimore classification

23
Q

Herpes Virus in New Classification

A

Herpes simplex 1 & 2, Varicellovirus (chickenpox)
• Fam: Herpesviridae
• Order: Herpesvirales
• Class: Herviviricetes
• Phylum: Peploviricota
• Kingdom: Heungongvirae
• Realm: Duplodnaviria (dsDNA) (class I of Baltimore classification)

24
Q

Influenza Virus in New Classification

A
Influenza A virus
• Fam: Orthomyxoviridae
• Order: Articulavirales
• Class: Insthoviricetes
• Phylum:Negarnaviricota ((-) ssRNA) (class V of Baltimore)
• Kingdom: Orthonavirae
• Realm: Ribioviria (RNA viruses)
25
Classification
placing organisms in groups of related species • Lists of characteristics of known organisms
26
Identification
matching characteristics of an "unknown" organism to lists of known organisms • Clinical lab identification
27
Bergey's Manual of Determinative Bacteriology
provides identification schemes for identifying | bacteria and archaea
28
Approved Lists of Bacterial Names
lists species of | known classification
29
Transport media
is used to collect and transport | pathogens to a laboratory
30
how many phylums are pathogenic?
5/24
31
Morphological characteristics
useful for identifying eukaryotes; tell little about phylogenetic relationships
32
Differential staining:
Gram staining, acid-fast | staining; not useful for bacteria without cell walls
33
Biochemical tests
determine presence of bacterial enzymes
34
FAME
Fatty acid methyl esters provide profiles | that are constant for a particular species
35
DNA fingerprint
Electrophoresis of restriction enzyme digests of an organism's DNA • Comparing fragments from different organisms provides information on genetic similarities and differences
36
DNA Chips
A DNA chip (also known as a microarray) contains DNA probes and detects pathogens by hybridization between the probe and DNA in the sample • Detected by fluorescence
37
Ribotyping
• Probing bacterial genome with 16S rRNA gene probe
38
Fluorescent in situ hybridization (FISH)
Fluorescent DNA or RNA probes stain the microorganisms being targeted • Determines the identity, abundance, and relative activity of microorganisms in an environment
39
Dichotomous keys
Identification keys based on successive questions
40
Cladograms
Maps that show evolutionary relationships among | organisms; based on rRNA sequences