🦠 Microbiology: One Night Revision & Cram Sheet
Explain how microbial structure, nutrition, and metabolism produce growth and survival in bacteria, archaea, eukaryotic microbes, and viruses, and how those facts decide the principles of control, the logic of virulence, and the microbial steps in element cycles and fermentations.
🌟 Core Axioms & High-Yield Golden Rules
7 Core PrinciplesNon-negotiable foundational truths frequently tested in direct conceptual and numerical exam questions. Click checkbox to mark as mastered.
Gram-positive bacteria have thick multi-layered peptidoglycan containing teichoic and lipoteichoic acids, and lack an outer membrane; retain crystal violet-iodine complex (purple).
💡 Gram Positive = Thick Peptidoglycan (Purple)Gram-negative bacteria have thin peptidoglycan, a periplasmic space, and an outer membrane with lipopolysaccharide (LPS: Lipid A endotoxin + core polysaccharide + O-antigen); decolorize and counterstain pink with safranin.
💡 Gram Negative = Outer Membrane + Lipid ABacterial endospores (Bacillus, Clostridium) possess dipicolinic acid complexed with calcium (Ca-DPA) and SASPs (small acid-soluble proteins) providing extreme resistance to heat, radiation, and desiccation.
💡 Dipicolinate = Spore heat armorBacterial growth curve phases: Lag phase (adaptation, enzyme synthesis), Log/Exponential phase (balanced rapid binary fission, maximal sensitivity to antibiotics), Stationary phase (nutrient depletion, toxic accumulation, spore formation), Death/Decline phase.
💡 Lag -> Log -> Stationary -> DeathAntimicrobial mechanisms: Penicillins/Cephalosporins inhibit peptidoglycan transpeptidases (PBPs); Vancomycin binds terminal D-Ala-D-Ala; Aminoglycosides bind 30S causing misreading; Macrolides/Chloramphenicol bind 50S; Fluoroquinolones inhibit DNA gyrase/topoisomerase IV.
💡 Cell wall = Beta-lactams | 30S = Aminoglycosides | 50S = MacrolidesBacterial Horizontal Gene Transfer: Transformation (uptake of free naked DNA from environment); Transduction (bacteriophage-mediated DNA transfer; Generalized in lytic vs Specialized in lysogenic); Conjugation (direct transfer via F-pilus and relaxosome).
💡 Transf = Free DNA | Transd = Phage | Conj = PilusBacterial flagella motor is embedded in the cell envelope and powered directly by the proton motive force (PMF / H+ or Na+ gradient), NOT by ATP hydrolysis.
💡 Flagella = Proton Motive Force driven📚 Chapter-by-Chapter Rapid Cram Breakdown
9 ModulesHigh-density review of every curriculum chapter. Click any chapter title to view full in-depth lecture notes.
Scope and history →
- Master What a microbe is: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master Hooke and Leeuwenhoek: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master Pasteur: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master Koch's postulates and their limits: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master pure culture as an idea: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master Nucleoid, ribosomes, inclusions, endospores: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master peptidoglycan: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master Gram envelopes: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master LPS: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master the acid-fast wall: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
Nutrition and growth →
- Master Nutrients: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master nutritional classes: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master growth curve: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master generation time: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master batch and chemostat: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master Substrate-level phosphorylation: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master aerobic and anaerobic respiration: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master fermentation: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master oxygenic and anoxygenic photosynthesis: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master nitrogen fixation: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
Viruses →
- Master Definition and structure: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master Baltimore classes: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master one-step growth: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master T-even lysis: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master lambda: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
Eukaryotic microbes →
- Master Yeasts and moulds: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master fungal spores: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master protozoan groups: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master *Plasmodium*: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master microbial algae: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master The four definitions: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master D-value: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master heat, filtration, radiation: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master chemical classes: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master drug targets: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master Microbiota and colonisation: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master virulence factors: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master exotoxin and endotoxin: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master AB toxins: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master molecular Koch: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master Carbon and nitrogen cycles: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master wastewater: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master food fermentations: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master primary and secondary metabolites: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
- Master biodegradation and bioremediation: understand underlying structural mechanisms, biochemical pathways, and diagnostic indicators.
⚖️ Must-Know Comparison & Distinction Tables
1 TablesSide-by-side matrices comparing commonly confused biological mechanisms, kinetic types, and pathways.
Gram-Positive vs. Gram-Negative Bacterial Envelope
| Characteristic | Gram-Positive Bacteria | Gram-Negative Bacteria |
|---|---|---|
| Peptidoglycan Layer | Thick (20 - 80 nm), multi-layered, heavily cross-linked | Thin (2 - 7 nm), single or few layers |
| Outer Membrane | Absent | Present (asymmetric bilayer: phospholipids inner, LPS outer) |
| Lipopolysaccharide (LPS) | Absent | Present (Endotoxin: Lipid A causes septic shock) |
| Teichoic / Lipoteichoic Acids | Present (antigenic and cell wall stability) | Absent |
| Periplasmic Space | Narrow or virtually absent | Prominent periplasm containing degradative enzymes & transport proteins |
⚠️ Examiner Traps & Common Student Mistakes
1 PitfallsClassic trap questions designed by examiners to catch uncritical students. Don't lose easy marks here!
Does Penicillin Kill Mycoplasma?
Thinking penicillin works on all bacteria.
Mycoplasma (e.g., Mycoplasma pneumoniae) naturally lacks a peptidoglycan cell wall (incorporates host sterols into membrane instead), making it completely INTRINSICALLY RESISTANT to all beta-lactams and vancomycin.
📐 Key Formulas & Numerical Constants
2 FormulasStandard Equilibrium Constant
Keq = [Products] / [Reactants]Determines direction of chemical/biological reactions at dynamic equilibrium.
Relative Quantitative Ratio
Ratio = Experimental_Value / Baseline_ControlStandardizes comparative fold-change in quantitative biological assays.
🏛️ Landmark Scientists & Nobel Discoveries
6 PioneersFrequently tested in historical milestone and match-the-following exam questions.
Lynn Margulis
🏅 National Medal of Science (1999); Member of the National Academy of Sciences (1983)Major landmark discoveries
Antonie van Leeuwenhoek
Major landmark discoveries
Louis Pasteur
Major landmark discoveries
Robert Heinrich Hermann Koch
🏅 Nobel Prize in Physiology or Medicine (1905) for his investigations and discoveries in relation to tuberculosisMajor landmark discoveries
Sir Alexander Fleming
🏅 Nobel Prize in Physiology or Medicine (1945) for the discovery of penicillin and its curative effect in various infectious diseasesMajor landmark discoveries
Martinus Willem Beijerinck
Major landmark discoveries
🎯 Rapid-Fire Active Recall Checklist
3 QuestionsTest your memory before stepping into the exam hall. Try to answer mentally, then tap "Reveal Answer" to verify!