Year 2 Medical Microbiology

• What does taxonomy refer to in microbiology?

  Classification based on shared characteristics
• How is taxonomy organized?

  It is organized hierarchically into groups based on shared properties
• Who is considered the founder of modern taxonomy?

  Carl Linnaeus
• What is phylogeny in the context of microbiology?

  It measures the evolutionary relationships between organisms
• What are the steps in the taxonomic classification of microbes?

  1. Classification: Ordering organisms into groups based on shared properties
  2. Nomenclature: Naming the classified organisms
  3. Identification: Determining the species of an unknown organism through comparison

  
• What are traditional properties used in the classification of bacteria?

  Microscopy, morphology, response to oxygen, mode of energy synthesis, and biochemical tests
• What are the molecular and genetic methods used in bacterial classification?

  • Choose appropriate molecular markers for a gene family
  • Amplify and sequence the markers
  • Create an evolutionary model
  • Conduct phylogenetic tree analysis and construction

  
• What is the basis of phylogeny?

  All living things have genes that mutate randomly at low frequency
• How do organisms that differ by a few DNA base changes relate to evolutionary time?

  They have diverged more recently in evolutionary time
• What are the sub-species classifications in bacterial taxonomy?

  • Biovar: biochemical/physiological variant
  • Morphovar: differ morphologically
  • Serovar/serotype: antigenic differences
• What distinguishes Salmonella from other S. enterica strains?

  Differences in host range and absence of flagella
• What are the phenotypic and chemotaxonomic methods for classifying a previously unrecorded microbe?

  • Genotypic: based on genetic similarities
  • Phenotypic: based on physical, structural, or metabolic features
  • Chemotaxonomic: measures biochemical composition similarity

  
• What would you do if you discovered a new microbe in a cave?

  Attempt to genotype the bacteria and compare with existing databases
• What are the classifications of bacteria based on their response to oxygen?

  • Aerobes: Thrive in O2 presence
  • Microaerophiles: Require O2 but cannot tolerate 21%
  • Anaerobes: Cannot tolerate O2
  • Facultative anaerobes: Prefer O2 but can grow without it

  
• What are examples of biochemical and enzymatic tests used in bacterial classification?

  • Cytochrome c test: produces a blue/purple pigment
  • Urease test: pH change indicates urease presence
  • Analytical profile index: multiple biochemical tests

  
• What are the similarities and differences between Archaea and Bacteria?

  Similarities:

  • Shape, size, and microscopic appearance
  • Both multiply by binary fission

  
  

  Differences:

  • Archaea do not have peptidoglycan
  • Archaea genes are more similar to eukaryotes
  • Different ribosome structure and RNA polymerase complexity

  
• What is the significance of the universal phylogenetic tree based on 16S sRNA analysis?

  It illustrates the three domains of life
• Why might Woese have faced resistance to his proposal for reclassification of Archaea?

  Due to the similarities and differences between Archaea and Bacteria
• What are the implications of classifying Archaea as a separate domain of life?

  It highlights the distinct evolutionary lineage of Archaea compared to Bacteria
• What are the hierarchical levels of taxonomy?

  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• What traditional properties are used in bacterial classification?

  Microscopy, morphology, response to oxygen, and biochemical tests

  
• What molecular and genetic methods are used in bacterial classification?

  • Choose appropriate molecular markers
  • Amplify and sequence DNA
  • Create evolutionary models
  • Conduct phylogenetic tree analysis

  
• What is the urease test used for?

  To determine if bacteria possess urease enzyme
• What does a positive urease test indicate?

  It indicates the presence of ammonia and a pH change to pink
• What is the temperature range for hyperthermophiles?

  113 – 200°C
• What is the pH level that acidophiles can tolerate?

  pH 1.0
• What is the pressure condition that barophiles can withstand?

  1200 atm
• What is the role of the analytical profile index in bacterial classification?

  It involves multiple biochemical and enzymatic tests for classification
• What is the significance of GC content in bacterial classification?

  It indicates the percentage of guanine and cytosine in DNA or RNA
• How do phenotypic and genotypic classification systems differ in their benefits?

  Phenotypic systems focus on observable traits, while genotypic systems focus on genetic similarities
• What is the classification of spore-forming bacteria?

  They are classified based on their response to oxygen
• What is the significance of the three domains of life model?

  It recognizes Archaea as a separate domain of life
• What is the main characteristic of methanogens?

  They are anaerobic CH4 producers
• What is the main characteristic of psychrophiles?

  They thrive at low temperatures, around -15°C
• What is the main characteristic of acidophiles?

  They thrive in acidic environments, with a pH of 1.0
• What is the main characteristic of hyperthermophiles?

  They thrive at extremely high temperatures, between 113 – 200°C
• What is the main characteristic of barophiles?

  They thrive under high pressure, around 1200 atm