FT104 General Microbiology Comprehensive Reviewer 2024-2025 PDF

FT104: GENERAL MICROBIOLOGY Comprehensive Reviewer – AY 2024-2025 1. Microbial Control Methods Key Points: Sterilization: Destroys all viable microbes, including spores (e.g., autoclaving). Pasteurization: Reduces microbial numbers but doesn’t sterilize (e.g., milk...

FT104: GENERAL MICROBIOLOGY Comprehensive Reviewer – AY 2024-2025 1. Microbial Control Methods Key Points: Sterilization: Destroys all viable microbes, including spores (e.g., autoclaving). Pasteurization: Reduces microbial numbers but doesn’t sterilize (e.g., milk processing). Filtration: Sterilizes heat-sensitive liquids by physically removing microbes. Moist Heat: Coagulates and denatures proteins (e.g., autoclaving). Dry Heat: Oxidizes and dehydrates cells. Memory Aid: Sterilization = All Dead, Pasteurization = Partial Reduction. Practice Questions: Which method sterilizes heat-sensitive liquids? Answer: Filtration. What is the mode of action of moist heat? Answer: Coagulation and denaturation of proteins. 2. Microbial Physiology Key Points: Growth Phases: Lag Phase: Cells adjust to the environment. Log Phase: Exponential reproduction occurs. Stationary Phase: Nutrient depletion halts growth. Death Phase: Cells die due to waste accumulation. Extremophiles: Halophiles thrive in high salt concentrations. Thermophiles require high temperatures. Examples: Halophiles like Halobacterium in salt flats. Thermophiles in hot springs. Practice Questions: During which phase do bacteria reproduce most rapidly? Answer: Log Phase. Which microorganism thrives in extreme salt conditions? Answer: Halophiles. 3. Microbial Genetics Key Points: Central Dogma: DNA → RNA → Protein. Transcription: DNA is converted into mRNA (via RNA polymerase). Translation: tRNA transports amino acids to ribosomes to form proteins. Mutations: Point Mutation: Alters a single nucleotide. Frameshift Mutation: Adds/deletes nucleotides, disrupting the reading frame. Memory Aid: Transcription = DNA to RNA, Translation = RNA to Protein. Practice Questions: What enzyme synthesizes RNA primers during DNA replication? Answer: Primase. What happens in a frameshift mutation? Answer: The reading frame is disrupted. 4. Microbial Roles in Biogeochemical Cycles Key Points: Nitrogen Cycle: Rhizobium fixes nitrogen gas into ammonia. Carbon Cycle: Decomposers release CO₂ by breaking down organic material. Sulfur Cycle: Sulfate-reducing bacteria convert sulfates to hydrogen sulfide. Practice Questions: Which microorganism fixes nitrogen? Answer: Rhizobium. What is the role of decomposers in the carbon cycle? Answer: Break down organic material to release CO₂. 5. Microbial Pathogenesis Key Points: Virulence Factors: Toxins: Damage tissues or disrupt functions. Adhesins: Facilitate attachment to host cells. Capsules: Prevent phagocytosis by host immune cells. Immune Responses: Innate Immunity: Non-specific defenses like inflammation. Adaptive Immunity: Specific responses, including T cell activation. Memory Aid: Capsules = Cloak of Invisibility for Bacteria. Practice Questions: How do capsules enhance bacterial pathogenicity? Answer: By preventing phagocytosis. What is an example of an innate immune response? Answer: Inflammation. 6. Microbial Applications in Industry and Environment Key Points: Bioremediation: Microorganisms break down pollutants into less harmful substances. Wastewater Treatment: Activated sludge breaks down organic pollutants. Antibiotic Production: Many antibiotics are derived from soil microbes (e.g., Streptomyces). Examples: Pseudomonas used to degrade oil spills. Activated sludge reduces organic waste in water treatment plants. Practice Questions: What is the main role of activated sludge? Answer: Breaking down organic pollutants. How does bioremediation address environmental issues? Answer: By breaking down pollutants into less harmful substances. 7. Food Microbiology and Safety Key Points: Psychrotrophs: Grow at refrigeration temperatures, causing spoilage (e.g., Listeria). Salting: Reduces water activity, inhibiting microbial growth. Practice Questions: Why are psychrotrophs a concern in food safety? Answer: They grow in refrigerated foods, causing spoilage. How does salting prevent microbial growth? Answer: Reduces free water availability. 8. Practical Microbiology Key Points: Turbidity: Indicates microbial growth in liquid cultures. Sterilization of Culture Media: Prevents contamination by killing all microorganisms. Refrigeration: Slows microbial growth by reducing metabolic activity. Practice Questions: What does a turbid culture indicate? Answer: Growth of microorganisms. Why sterilize culture media before use? Answer: To prevent contamination. 9. Study Tips for Microbiology Understand Key Concepts: Focus on the “why” behind microbial processes. Use Mnemonics: Simplify recall with memory aids like “Central Dogma: DNA → RNA → Protein.” Practice Questions: Test yourself using the provided questions. Visual Aids: Use flowcharts for cycles like nitrogen and carbon.