Microbiology midterm

Here's an extensive study guide on your microbiology topics:

1. Structures of Macromolecules

• DNA:

  • Monomer: Nucleotide (phosphate group, deoxyribose sugar, nitrogenous base).

  • Polymer: Polynucleotide (double-stranded helix).

  • Examples: Adenine (A), Thymine (T), Cytosine (C), Guanine (G).

• RNA:

  • Monomer: Nucleotide (phosphate group, ribose sugar, nitrogenous base).

  • Polymer: Polynucleotide (single-stranded).

  • Examples: Adenine (A), Uracil (U), Cytosine (C), Guanine (G).

• Lipids:

  • Monomer: Fatty acids and glycerol.

  • Structure: Hydrophobic tail (fatty acid chains) and hydrophilic head (glycerol/phosphate in phospholipids).

  • Examples: Phospholipids, triglycerides, cholesterol.

• Proteins:

  • Monomer: Amino acids (amino group, carboxyl group, R-group).

  • Polymer: Polypeptide chains.

  • Examples: Enzymes, antibodies, hormones.

• Carbohydrates:

  • Monomer: Monosaccharides (simple sugars like glucose).

  • Polymer: Polysaccharides (starch, glycogen, cellulose).

  • Examples: Glucose, sucrose, cellulose, glycogen.

2. Functional Groups

• Alcohols: Hydroxyl group (-OH).

• Amino Acids: Amine group (-NH2) and carboxyl group (-COOH).

• Esters: Formed by a reaction between an alcohol and a carboxylic acid (-COOR).

3. Bonds

• Ionic Bonds: Transfer of electrons between atoms (e.g., NaCl).

• Covalent Bonds: Sharing of electrons between atoms (e.g., H2O).

• Hydrogen Bonds: Attraction between a hydrogen atom and electronegative atoms like oxygen or nitrogen (e.g., DNA base pairing).

4. Stains

• Simple Stain: Uses one dye to view cell shape and arrangement.

• Gram Stain: Differentiates between Gram-positive (purple) and Gram-negative (pink) bacteria.

• Acid-Fast Stain: Stains Mycobacterium species with a red dye (carbolfuchsin) that resists decolorization.

• Negative Stain: Stains the background, leaving cells unstained (used for capsules).

5. Microscopes

• Compound Light Microscope: Uses light to view samples; max magnification is 1000x, image appears bright.

• Phase-Contrast Microscope: Enhances contrast in unstained cells; used for live specimens.

• Darkfield Microscope: Shows specimens against a dark background, useful for viewing live, unstained cells.

• Fluorescence Microscope: Uses fluorochromes to emit light when exposed to UV radiation.

• Electron Microscope: Uses electron beams for high magnification and resolution; includes transmission (internal structures) and scanning (surface structures).

6. Transport Mechanisms

• Simple Diffusion: Movement from high to low concentration.

• Passive Transport: No energy required; includes osmosis and facilitated diffusion.

• Active Transport: Requires energy (ATP); moves substances against their concentration gradient.

• Hypotonic: Cell swells as water enters.

• Hypertonic: Cell shrinks as water exits.

• Isotonic: No net movement of water.

7. Cell Arrangement

• Cocci, bacilli, spirilla, chains (strepto-), clusters (staphylo-).

8. Endospores

• Properties: Resistant to heat, chemicals, radiation; dormant structure for survival.

• Function: Protects bacterial genome in harsh conditions.

9. Glycocalyx

• Properties: Sticky outer layer, composed of polysaccharides/proteins.

• Function: Protection, attachment, evasion of the immune system.

10. Energy Sources

• Photoautotroph: Energy from light, carbon from CO2.

• Photoheterotroph: Energy from light, carbon from organic compounds.

• Chemoautotroph: Energy from chemical reactions, carbon from CO2.

• Chemoheterotroph: Energy and carbon from organic compounds.

11. Respiration & Fermentation

• Aerobic Respiration: Reactants: glucose, oxygen; Products: CO2, water, ATP.

• Fermentation:

  • Lactic acid fermentation: Glucose → Lactic acid + ATP.

  • Alcohol fermentation: Glucose → Ethanol + CO2 + ATP.

• Electron Transport Chain: Series of redox reactions, produces ATP via oxidative phosphorylation.

12. Bacterial Growth

• Aerotolerant Aerobes: Tolerate oxygen but do not use it.

• Facultative Anaerobes: Use oxygen when available, but can grow without it.

• Growth Curve: Lag, log, stationary, death phases.

• Optimal Growth Temperatures:

  • Psychrotroph: Cold-tolerant (20°C-30°C).

  • Mesophile: Moderate temperatures (20°C-45°C).

  • Thermophile: Heat-loving (45°C-70°C).

  • Hyperthermophile: Extreme heat (>70°C).

  • Psychrophile: Extreme cold (<20°C).

13. Physical/Chemical Growth Factors

• Bacteriostatic: Inhibits growth.

• Germicide: Kills microbes.

• Virucide: Inactivates viruses.

• Sterilant: Completely destroys all forms of microbial life.

• Fungicide: Kills fungi.

• Disinfectant: Applied to inanimate objects.

• Antiseptic: Applied to living tissue.

• Aseptic: Free from contamination.

14. Sterilization Methods

• Autoclave: Uses steam and pressure to sterilize.

• Lyophilization: Freeze-drying for preservation.

• Nonionizing Radiation: UV light damages DNA.

• Freezing: Inhibits microbial growth.

• Ionizing Radiation: X-rays and gamma rays to sterilize.

• Pasteurization: Heat to kill pathogens without spoiling the product.

15. Enzymes in Replication & Transcription

• Replication: DNA polymerase (copies DNA), helicase (unwinds DNA), ligase (joins fragments).

• Transcription: RNA polymerase (synthesizes RNA).

16. Gene Transfer

• Transduction: DNA transfer via bacteriophage.

• Transformation: Uptake of free DNA from the environment.

• Conjugation: Transfer of DNA via pilus.

17. PCR:

• Steps: Denaturation, annealing, extension.

• Rationale: Amplifies specific DNA sequences.

18. Biotechnology

• Gene Production: Insert gene into vector, transform into host cells (bacteria/yeast/mammalian cells), express protein.

• DNA Fingerprinting: Identifies genetic differences in individuals.

19. Microbial Growth Factors

• Physical/Chemical Conditions: Temperature, pH, oxygen levels, nutrients.

• Metabolism: Energy exchange (catabolic and anabolic reactions).

20. Evolution & Endosymbiosis

• The theory that mitochondria and chloroplasts originated from free-living bacteria engulfed by a eukaryotic cell.

21. Antibiotic Resistance

• Factors: Overuse, misuse, mutations, gene transfer.

• Genetic Changes: Mutations, plasmids, transposons that confer resistance.