Week 2

• Who is the module leader for the course on Microbial Life?

  1. Caray A Walker
• What is the focus of the module on Microbial Life?

  Cell structure and function
• What is peptidoglycan?

  A structural component of bacterial cell walls
• What distinguishes Gram positive from Gram negative bacteria?

  Differences in cell wall structure
• What are the main traits shared by most bacteria?

  Thick outer envelope, compact genome
• Why do prokaryotic genomes maximize cell production?


  They have relatively little noncoding DNA
• What role does the cell's structure play in bacterial reproduction?


  Enables a high rate of reproduction
• What are the key differences between prokaryotes and eukaryotes?

  • Prokaryotes: 1-10 micrometres, no nuclear envelope, no membrane-bound organelles
  • Eukaryotes: 10-100 micrometres, have nuclear envelope, have membrane-bound organelles
• What unique features do Archaea possess compared to bacteria?

  Unique membrane structures for extreme environments
• Why does ethanol kill bacteria while water does not?

  Ethanol disintegrates membranes, water does not
• What are the common chemical components found in all cells?

  • Water
  • Essential ions (potassium, magnesium, chloride)
  • Small organic molecules (lipids, sugars)
  • Macromolecules (nucleic acids, proteins)
• What is the composition of the cytoplasm in bacterial cells?

  A gel-like network of proteins and macromolecules
• What is the structure of the Gram-negative bacterial cell wall?

  Composed of peptidoglycan and surrounded by membranes
• What is the function of the periplasm in Gram-negative bacteria?

  Contains nutrient-binding proteins and secretion machines
• What is the outer membrane of Gram-negative bacteria composed of?

  Phospholipids and lipopolysaccharides
• What is the role of the capsule in bacteria?

  Inhibits phagocytosis and provides protection
• What are the main components of the bacterial cell wall?

  • Peptidoglycan (rigid component)
  • Teichoic acid (in Gram-positive bacteria)
  • Lipopolysaccharide (in Gram-negative bacteria)
• Who invented the Gram stain and in what year?

  Christian Gram in 1884
• How do Gram-positive bacteria react to the Gram stain?

  They retain purple crystal violet stain
• What are the functions of pili and flagella in bacteria?


  • Pili: Attachment structures and gene transfer
  • Flagella: Motility and movement
• What proteins determine bacterial cell shape?


  FtsZ, MreB, and CreS
• What happens to Gram-negative bacteria during Gram staining?


  Crystal violet is washed out, counterstained pink
• What is the function of flagella in bacteria?

  Used for motility and movement
• How are flagella assembled in bacteria?

  Subunits migrate through a central pore
• What are fimbriae or pili composed of?

  Protein structures called fimbrins or pilins
• What is the role of capsules in bacteria?

  Provide food reserves and protection
• What is the structure of the nucleoid in bacterial cells?


  Contains covalently closed circular DNA
• How is DNA organized in the nucleoid?

  Forms about 50 loops or domains
• What initiates the formation of endospores in some Gram-positive bacteria?


  Starvation triggers a genetic program
• What are the stages of endospore development?

  1. Asymmetrical cell division
  2. Formation of forespore
  3. Development into endospore
  4. Activation, germination, and outgrowth into vegetative cells
• Who is the module leader for "How do Microbes Grow?"

  1. Caray A Walker
• What are the key differences in bacterial cell structure?

  • Variation in cell wall structure (Gram + and -)
  • Immunogenic outer membrane (LPS)
  • Different types of flagella for movement
  • Different types of pili for attachment and gene transfer
  • Capsules for protection
  • Dormant spores for survival in extreme conditions
• What are the learning outcomes for the module?

  • List nutritional requirements
  • Describe bacterial culture techniques
  • Draw and describe bacterial growth curves
  • Describe bacterial cell development and differentiation
• Why do microorganisms need sources of carbon and energy?

  To grow and increase cell mass and number
• How do yeast utilize glucose during metabolism?

  They break it down to produce ethanol and CO2
• How quickly can one E. coli cell divide?

  Every 20-30 minutes
• What limits microbial growth?

  Nutrient supplies
• What are essential nutrients for microbes?

  Compounds they must import and cannot make
• What are the six macronutrients needed in large quantities by microbes?

  • Carbon
  • Nitrogen
  • Phosphorus
  • Hydrogen
  • Oxygen
  • Sulfur
• What role do micronutrients play in microbial growth?


  They act as cofactors for specific enzymes