Microbiology Exam Study Guide PDF

**[Lecture 2: Microbiology History]** Key Figures in Microbiology Antonie van Leeuwenhoek (1670s) -- First to observe microorganisms (\"animalcules\") using a single-lens microscope. Louis Pasteur (1850s-60s) -- Disproved spontaneous generation using swan-neck flask experiments; developed pasteur...

**[Lecture 2: Microbiology History]** Key Figures in Microbiology Antonie van Leeuwenhoek (1670s) -- First to observe microorganisms (\"animalcules\") using a single-lens microscope. Louis Pasteur (1850s-60s) -- Disproved spontaneous generation using swan-neck flask experiments; developed pasteurization to kill microbes in food & liquids. Robert Koch (1870s-80s) -- Developed Koch's Postulates, a method to link specific microbes to diseases (e.g., Bacillus anthracis → anthrax). Joseph Lister (1860s) -- Pioneered antiseptic techniques to prevent infection during surgery. Edward Jenner (1796) -- Developed first vaccine (smallpox). Germ Theory of Disease Microorganisms are the cause of infectious diseases. Led to aseptic techniques, vaccines, and antibiotics. **[Lecture 3: Bacterial Cell Learning Objectives]** ** Know major bacterial cellular components and their functions** Cell Wall: Provides shape & protection from osmotic pressure ex:Gram-positive (thick peptidoglycan) & Gram-negative (thin peptidoglycan + outer membrane) Plasma Membrane: Selectively permeable, controls transport ex:Found in all bacteria Ribosomes: Protein synthesis, made of 30S & 50S subunits (total: 70S) ex:Targeted by antibiotics (e.g., tetracyclines) Nucleoid: Region where bacterial DNA is located (no nucleus) ex:Circular, double-stranded DNA Flagella: Movement (chemotaxis) ex:Escherichia coli Pili & Fimbriae: Attachment, conjugation (gene transfer) ex:Neisseria gonorrhoeae Capsule: Protects against immune system (phagocytosis) ex:Streptococcus pneumoniae ** Understand basic principals governing bacterial size and shapes.** Cocci (spherical) -- Staphylococcus (clusters), Streptococcus (chains). Bacilli (rod-shaped) -- E. coli (single rods), Bacillus (chains). Spirilla (spiral-shaped) -- Helicobacter pylori (causes ulcers) **[Lecture 4: Growth of Microbal Cells and Populations Learning goals:]** **1. Understand exponential growth of microbial populations in a nutrient-rich environment.** Bacteria grow **exponentially** when nutrients are **abundant**, meaning their population **doubles** at a constant rate. Growth follows the equation:\ Nt=N0×2(t/G)Nt​=N0​×2(t/G) - - - **Example**: If a bacterial culture starts with **100 cells**, has a **generation time of 20 minutes**, and grows for **3 hours**:\ Nt=100×2(180/20)Nt​=100×2(180/20)Nt=100×29=51,200 cellsNt​=100×29=51,200 cells **2. Be able to calculate the generation time (G) of a microbial population using equations, graphs, and common sense.** **Generation time** (GG) = the time it takes for a **bacterial population to double**. Formula:\ G=tnG=nt​ - - **Example Calculation Using a Graph**: - - - **3. Know and understand the different phases of the microbial growth curve.** **Lag Phase** -- No division, cells adjust to environment. **Log (Exponential) Phase** -- **Rapid division**, optimal metabolism. Best time for **antibiotic treatment**. **Stationary Phase** -- Nutrients deplete, waste accumulates, **growth = death rate**. **Death Phase** -- Cells **die faster than they divide** due to toxic conditions. **4. Get to know the Microbe of the Day: Streptomyces** - - - **5. Know the difference between primary and secondary metabolism.** Primary Metabolism: Essential for growth ex:DNA, RNA, proteins, ATP Secondary Metabolism: Not needed for growth, occurs in stationary phase ex:Antibiotics (penicillin), toxins **6. Understand how Quorum Sensing allows bacteria to work together when they grow to high population densities (e.g. in a biofilm)** **Quorum sensing** allows bacteria to **detect population density** and change behavior when numbers are high. Uses **autoinducers** (signaling molecules). **Examples of Quorum Sensing in Action**: - - - **[Lecture 5: Environmental Constraints on Growth]** **1. Know and understand the different phases of the microbial growth curve** Bacteria follow a predictable **growth curve** when in a closed system with limited nutrients. 1. - - 2. - - 3. - - 4. - - **2. Understand how Quorum Sensing allows bacteria to work together when they grow to high population densities (e.g. in a biofilm)** - - - - - - **3. Get to know the Microbe of the Day: Pseudomonas aeruginosa** **Gram-negative, rod-shaped**, opportunistic pathogen. Can survive in **diverse environments** (soil, water, hospitals). Forms **biofilms**, making infections difficult to treat. Produces **green-blue pigments** (pyocyanin, pyoverdine). **Diseases**: Causes infections in cystic fibrosis patients & burn victims **4. Understand how different environmental factors (e.g. pH, temp., pressure, O 2 etc.) affect the growth, activity, and diversity of microbes in nature.** Temperature: Determines enzyme function & membrane stability ex:Thermus aquaticus (Taq polymerase, heat-resistant) pH: Affects protein structure & metabolism ex:Helicobacter pylori (acid-tolerant, stomach ulcers) Oxygen: Determines metabolism type (aerobic vs. anaerobic) ex:Clostridium botulinum (strict anaerobe) Pressure: High pressure can denature proteins, affect membranes ex:Barophiles in deep-sea vents **5. Know the difference between primary and secondary metabolism and what things are produced during secondary metabolism.** Primary Metabolism: Supports growth & reproduction ex:DNA, RNA, proteins, ATP Occurs during log (exponential) phase Secondary Metabolism: Produces non-essential compounds that offer competitive advantages ex:Antibiotics (penicillin, streptomycin), pigments, toxins Occurs during stationary phase **[Lecture 6: Biofilms]** **What Are Biofilms?** - - ### **Biofilm Formation Stages** 1. 2. 3. 4. ### **Why Are Biofilms Important?** - - ### **Microbe Example: *Pseudomonas aeruginosa*** - - **[Lecture 7: Microbial Metabolism: Energetics and Catabolism Learning goals:]** **1. Understand how microbes break down large molecules outside the cell and transport smaller molecules across their membranes.** **Exoenzymes** break down large molecules outside the cell (e.g., proteases digest proteins). Small molecules (e.g., sugars, amino acids) are transported inside using: - - **2. Review redox reactions in the context of catabolism.** **Oxidation** = Loss of electrons (energy released). **Reduction** = Gain of electrons (energy stored). Redox reactions drive **ATP production** in cellular respiration. **3. Discuss where catabolic processes occur in bacterial cells.** Glycolysis: inCytoplasm Krebs Cycle (TCA Cycle): In Cytoplasm Electron Transport Chain (ETC): In Plasma membrane **4. Understand and appreciate the different types of microbial metabolism in terms of how they obtain energy and carbon.** Type Energy Source Carbon Source Example Photoautotrophs Light CO₂ Cyanobacteria Chemoautotrophs Inorganic chemicals CO₂ Nitrosomonas Photoheterotrophs Light Organic compounds Purple non-sulfur bacteria Chemoheterotrophs Organic compound Organic compounds E. coli **5. Explain the order in which electron donors are used by different organisms (or the same organism) in nature (based on ATP yield).** - 1. 2. 3. 4. **6. Understand the connection between respiration and electricity.** Some bacteria use **electron transport chains (ETC) to generate electricity** (bioelectrogenesis). *Geobacter* can transfer electrons to metal surfaces, used in **microbial fuel cells**. **7. Be able to describe electron flow in fermentation reactions (i.e. when there is no electron transport chain).** **No oxygen → No ETC → No oxidative phosphorylation**. **Alternative process**: - **[Lecture 8 and 9: Bacterial Genetics Learning Goals:]** ** Understand key differences between transcription and translation in Bacteria compared to Eukaryotes.** Transcription & Translation: Bacteria: Happen simultaneously (no nucleus) Eukaryotes: Separate processes (transcription in nucleus, translation in cytoplasm) mRNA Processing Bacteria: No introns, no splicing Eukaryotes: Introns removed, mRNA modified Ribosomes Bacteria: 70S (targeted by antibiotics) Eukaryotes: 80S ** Understand how antibiotics target translation via ribosome functioning.** - - - ** Understand the three ways bacteria transfer genetic information, and how these were discovered experimentally.** Process Mechanism Example Transformation Bacteria uptake naked DNA from the environment Streptococcus pneumoniae Conjugation Plasmid transfer via sex pilus E. coli Transduction Bacteriophages (viruses) transfer DNA between bacteria Salmonella ** Understand the function of CRISPR in bacterial and archaeal cells.** - - -