General Microbiology — High-Yield Review

Highest-Yield Facts by Unit

Unit 1 — Fundamentals

• High yield: Spontaneous generation was disproved by Pasteur; Koch's postulates link a microbe to disease (with modern limitations).
• High yield: Gram-positive = thick peptidoglycan; Gram-negative = thin peptidoglycan + outer membrane (LPS/lipid A).
• Three domains: Bacteria, Archaea, Eukarya.

Unit 2 — Metabolism

• High yield: Glycolysis → pyruvate; aerobic respiration = full ETC/oxidative phosphorylation (most ATP); fermentation regenerates NAD⁺ without oxygen.
• Glycolysis net 2 ATP (substrate-level); ETC/chemiosmosis via proton motive force + ATP synthase.

Unit 3 — Growth & Control

• High yield: Growth curve = lag → log → stationary → death; binary fission.
• Oxygen classes: obligate aerobe / facultative / obligate anaerobe / aerotolerant / microaerophile.
• Sterilization (all microbes) vs disinfection (pathogens) vs antisepsis (living tissue).
• Resistance: efflux pumps, target modification, enzymatic inactivation, reduced permeability.

Unit 4 — Genetics

• High yield: Semi-conservative replication; transcription + translation (central dogma).
• Lac operon = inducible; trp operon = repressible.
• Horizontal gene transfer: transformation, transduction, conjugation (F plasmid).

Unit 5 — Virology

• High yield: Lytic vs lysogenic (prophage); retroviruses use reverse transcriptase.
• Enveloped vs non-enveloped; positive-sense vs negative-sense RNA.

Unit 6 — Pathogenesis

• High yield: Exotoxin (protein, specific) vs endotoxin (lipid A, fever/sepsis).
• Virulence factors: adhesins, capsules, antigenic variation, siderophores.
• Incidence (new cases) vs prevalence (total cases); endemic/epidemic/pandemic.

Unit 7 — Immunology

• High yield: Innate (nonspecific: skin, phagocytes, complement) vs adaptive (specific: B/T cells, memory).
• Active vs passive immunity; primary vs secondary response (faster, larger, memory).

Unit 8 — Applied/Clinical

• High yield: Antibiotics target cell wall, protein synthesis, nucleic acids, membrane, folic acid.
• Nitrogen cycle: fixation, nitrification, denitrification; coliforms = water-quality indicators.

Comparison Tables

Cumulative Self-Check (20 questions)

1. Who disproved spontaneous generation?
2. Name the three domains of life.
3. What is the key structural difference between Gram-positive and Gram-negative cell walls?
4. What is the net ATP yield of glycolysis?
5. Which process regenerates NAD⁺ without oxygen?
6. List the four phases of the bacterial growth curve.
7. Differentiate sterilization from disinfection.
8. Name three mechanisms of antimicrobial resistance.
9. What is the central dogma?
10. Differentiate the lac and trp operons.
11. Name three mechanisms of horizontal gene transfer.
12. Differentiate the lytic from the lysogenic cycle.
13. What enzyme do retroviruses use?
14. Differentiate exotoxin from endotoxin.
15. Define incidence versus prevalence.
16. Differentiate innate from adaptive immunity.
17. Differentiate active from passive immunity.
18. Name the five antibody classes.
19. What does the complement system's membrane attack complex do?
20. Name the four main nitrogen-cycle microbial transformations.

Answers and Rationales

1. Louis Pasteur (biogenesis over spontaneous generation).
2. Bacteria, Archaea, Eukarya.
3. Gram-positive = thick peptidoglycan; Gram-negative = thin + outer membrane (LPS).
4. 2 ATP (substrate-level phosphorylation).
5. Fermentation.
6. Lag, log/exponential, stationary, death.
7. Sterilization kills/removes all microbes; disinfection reduces pathogens on surfaces.
8. Efflux pumps, target modification, enzymatic inactivation, reduced permeability.
9. DNA → RNA → protein.
10. Lac = inducible; trp = repressible.
11. Transformation, transduction, conjugation.
12. Lytic = immediate lysis; lysogenic = prophage integration (dormant).
13. Reverse transcriptase.
14. Exotoxin = secreted protein (specific); endotoxin = lipid A (fever, sepsis).
15. Incidence = new cases over time; prevalence = total cases at a point.
16. Innate = nonspecific/rapid/no memory; adaptive = specific/with memory.
17. Active = own immune response; passive = transferred antibodies.
18. IgG, IgM, IgA, IgE, IgD.
19. Forms pores in microbial membranes (lysis).
20. Nitrogen fixation, ammonification, nitrification, denitrification.

Last-Minute Review

• Structures: Gram +/- walls, endospores, capsules, flagella, pili, fimbriae; viral capsid/envelope.
• Growth: binary fission, growth curve, oxygen/temperature/pH classes, biofilms.
• Control: physical (heat, autoclave, pasteurization, filtration, radiation) vs chemical (halogens, alcohols, aldehydes); MIC/MBC; Kirby-Bauer.
• Genetics: replication, transcription, translation, operons, mutations, HGT.
• Viruses: lytic/lysogenic, retroviruses, prions, viroids.
• Epidemiology: transmission modes, reservoirs, endemic/epidemic/pandemic.
• Immunity: innate vs adaptive; antibodies; complement; vaccines; hypersensitivity types I-IV.
• Applied: biogeochemical cycles, food/industrial microbiology, disease systems.

Related

• Subject overview
• Topic 03 — Prokaryotic Cell Structure and Function
• Topic 12 — Antimicrobial Drugs and Resistance
• Topic 22 — Adaptive Immunity