Questions and Answers
An early attempt by Cohn at bacterial classification grouped bacteria according to their
In 1908, Orla-Jensen suggested that bacteria be grouped according to their
In the 1930s, Kluyver and van Niel proposed a classification scheme based on
In 1970, Stanier proposed that classification be based on
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Woese was involved in determining rRNA sequences and proposed breaking prokaryotes into two groups.
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Which technique(s) is/are used to help identify and classify bacteria?
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In higher organisms, successful mating can occur between members of the same
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From most general to most specific, which is the correct order?
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The basic taxonomic unit in the classification scheme of plants and animals is
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The three domain classification scheme uses
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The reference for taxonomic descriptions of bacteria is
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The name Lactococcus (Streptococcus) lactis indicates that Streptococcus is the old genus name.
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Very often clinically relevant information may be obtained by examining
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Gram-positive encapsulated diplococci found in sputum is indicative of
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Intracellular Gram-negative diplococci found in a urethral sample from a male is indicative of
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Mycobacterium tuberculosis is one of the few species of bacteria that are acid fast.
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A soluble greenish pigment is produced by
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A selective growth medium
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Streptococcus pyogenes would be
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Media that changes color as a result of the biochemical activity of growing bacteria usually contain a
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A breath test assaying for radioactive carbon dioxide may be used to indicate the presence of
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APITM, EnterotubeTM, and VitekTM are all
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Serological methods are used to identify bacteria.
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Fatty acid analysis is used to
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Nucleic acid techniques have great power as diagnostic tools because they may be
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DNA probes have been very useful in
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Organisms that grow very slowly, are non-culturable, are present in very small numbers or are mixed with a number of other bacteria may still be identified using
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Which of the rRNA molecules has proven the most useful in taxonomy/identification?
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Two isolates with identical RFLPs are considered
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Strain differences are helpful in
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Various strains of E. coli
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E. coli O157:H7 does not ferment sorbitol and produces a toxin.
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In E. coli O157:H7, the O157:H7 refers to the
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Phenotypically identical bacteria look the same and may be told apart by
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Phage typing is used to distinguish bacterial strains.
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The more closely related two organisms are, the more similar the
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The point at which two organisms diverged from a common ancestor is called
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Study Notes
Bacterial Classification
- Early classification by Cohn grouped bacteria based on shape.
- In 1908, Orla-Jensen suggested grouping bacteria by physiology.
- Kluyver and van Niel's 1930s classification was based on presumed evolutionary relationships.
- Stanier proposed in 1970 that classification should focus on DNA sequences.
- Woese contributed to identifying rRNA sequences and divided prokaryotes into two groups.
Identification Techniques
- Various techniques are utilized for bacteria identification and classification.
- Important taxonomic unit in classification is species.
- The three-domain classification includes Archaea, Bacteria, and Eucarya.
- Bergey's Manual of Systematic Bacteriology serves as the reference for bacterial taxonomy.
- Commercial methods like APITM, EnterotubeTM, and VitekTM assist in bacterial identification.
Clinical Implications
- Clinically relevant information can be derived from wet mounts and examining organism size and shape.
- Gram-positive encapsulated diplococci in sputum indicate Streptococcus pneumoniae.
- Intracellular Gram-negative diplococci in urethral samples suggest Neisseria gonorrhea.
- Mycobacterium tuberculosis is notably one of the few acid-fast bacteria.
Bacterial Properties
- Pseudomonas aeruginosa produces a soluble greenish pigment.
- Selective growth media promote the growth of specific bacteria.
- Streptococcus pyogenes is characterized as beta-hemolytic and catalase negative.
- Media that change color due to bacterial activity usually contain pH indicators.
Diagnostic Techniques
- Breath tests that check for radioactive carbon dioxide can indicate Helicobacter pylori presence.
- Serological methods are comprehensive and confirm various bacterial identifications.
- Fatty acid analysis aids in identifying bacteria, highlighting their biochemical signatures.
Molecular and Genetic Diagnosis
- Nucleic acid techniques offer specific identification capabilities.
- DNA probes are effective for identifying pure cultures of organisms.
- PCR is advantageous for identifying slow-growing or non-culturable organisms.
- The 16S rRNA molecule is especially useful for taxonomy and identification.
- Organisms with identical RFLPs might be considered the same strain, useful in outbreak tracing.
Strain and Phenotypic Analysis
- Strains of E. coli can vary from disease-causing to harmless.
- E. coli O157:H7 is distinctive for not fermenting sorbitol and toxin production.
- O157:H7 signifies the specific LPS and flagella types in E. coli.
- Phage typing assists in distinguishing among bacterial strains.
- Closely related organisms show similar nucleic acid sequences, indicating evolutionary connections.
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Description
Test your knowledge with these flashcards from Microbiology Chapter 10, focusing on the classification of bacteria. Explore key historical contributions to bacterial classification and understand the various schemes proposed over time. Perfect for students looking to reinforce their learning.
