microbiology

• What are the main types of micro-organisms?

  Bacteria, fungi, protoctists, and viruses
• What role do some bacteria and fungi play in the ecosystem?

  They decompose dead organisms, recycling nutrients
• How can bacteria be classified based on their effects on humans and animals?

  Some are pathogens, while others are beneficial
• How do bacteria reproduce?

  They reproduce asexually by binary fission
• How many bacteria are estimated to be in the human gut?

  Approximately one hundred trillion
• What is the standard form of one hundred and forty trillion?

  1.4 x 10$^{14}$
• What is the typical size range of bacteria?

  1 to 10 µm in length
• What is the diameter of E. coli?

  1.8 µm
• What is the formula for calculating magnification?

  M = I/A
• What is the magnification of a bacterium that is 2 µm in size and appears 49,000 µm under a microscope?

  $24,500$
• What are the main shapes used to classify bacteria?

  • Coccus (spherical)
  • Bacillus (rod-shaped)
  • Spirillum (spiral)

  
• How can bacteria be grouped based on their arrangement?

  Individually, in pairs, chains, or clusters
• What is an antigen?

  A molecule that triggers antibody production
• What is the purpose of the Gram stain technique?

  To distinguish between Gram-positive and Gram-negative bacteria

  
• What is the first step in the Gram staining process?

  Application of crystal violet dye
• What color do Gram-positive bacteria appear after staining?

  Purple

  
• What color do Gram-negative bacteria appear after staining?

  Red/pink

  
• Why do Gram-positive and Gram-negative bacteria stain differently?

  Due to differences in cell wall composition

  
• What is the structure of Gram-positive bacterial cell walls?

  Thick peptidoglycan layer, no outer membrane

  
• What is the structure of Gram-negative bacterial cell walls?

  Thin peptidoglycan layer, outer lipopolysaccharide membrane

  
• What is the optimum temperature for mammalian pathogens?

  Approximately 37°C
• What do bacteria require for growth in terms of pH?

  Slightly alkaline conditions
• What are obligate aerobes?

  Bacteria that require oxygen to survive
• What are obligate anaerobes?

  Bacteria that cannot survive in oxygen
• What are facultative anaerobes?

  Bacteria that prefer oxygen but can survive without it
• What is the role of Clostridium perfringens?

  It is an obligate anaerobe that produces toxins
• What is the effect of hyperbaric oxygen treatment on Clostridium perfringens infections?

  It improves patient health by inhibiting bacteria
• What nutrients do bacteria require for growth?

  Carbon source (usually glucose) and nitrogen
• What is the main carbon source for bacteria in the lab?

  Glucose
• What is the purpose of aseptic technique?

  To prevent contamination of cultures
• What are the phases of bacterial population growth?

  1. Lag phase
  2. Log phase
  3. Stationary phase
  4. Death phase
• What happens during the lag phase of bacterial growth?

  No cell division, intense metabolic activity
• What occurs during the log phase of bacterial growth?

  Rapid increase in numbers, no limiting factors
• What happens during the stationary phase of bacterial growth?

  Limiting factors prevent further growth
• What occurs during the death phase of bacterial growth?

  Death rate exceeds cell division
• How do you calculate the percentage decrease in bacteria?

  Decrease = (initial - final) / initial
• What is the formula for calculating antilog?

  Antilog$_{10} x$ = $10^x$
• What is the net ATP yield from glycolysis?

  2 ATP
• What are the similarities between aerobic and anaerobic respiration?

  Both involve glycolysis and produce ATP
• What are the differences between aerobic and anaerobic respiration?

  Aerobic uses oxygen; anaerobic does not