Microbiology Textbook PDF

**Types of Microscopes** **A- Light Microscopes** (use visible light) Ocular lens & objective lens Final magnification: Multiply the enlarging power of both the ocular and objective lenses Example: ×10 times ×4 = ×40 **Some Types of Light Microscope:** **1- Bright-field microscope** Background is...

**Types of Microscopes** **A- Light Microscopes** (use visible light) Ocular lens & objective lens Final magnification: Multiply the enlarging power of both the ocular and objective lenses Example: ×10 times ×4 = ×40 **Some Types of Light Microscope:** **1- Bright-field microscope** Background is lighter than observed specimen Most specimens require fixing and staining **2- Dark-field microscope** Used to view unfixed, unstained specimens Such as living organisms Background dark, specimen bright **3- Phase-Contrast Microscope** Used to view unfixed, transparent specimens Effective for observation of cell division, cell motility & dynamic states of cell organelles **4- Fluorescence Microscopes** Visualize specimens that contain naturally fluorescent substances or that have been stained with fluorescent stain **5- Confocal Microscopes** Sharper images than traditional microscopes Allows visualization of different planes of a specimen Image can be displayed three-dimensionally with "electronic staining" **B- Electron Microscopes:** use electrons as a source of energy **1-Transmission (TEM)** Electron beams go through specimen Special preparation, sectioning, and staining Two-dimensional images Good internal detail **2-Scanning (SEM)** No sections Scans the surface of an object Three-dimensional image \*Scanning Electron Micrograph of Campylobacter **Chemistry of Life** Matter: anything that occupies space & has mass (solid, liquid, gas), composed of Elements Chemical compound: elements in combination Atoms: smallest particles of an element Atomic nucleus: contains protons & neutrons Protons: positively charged particles Neutrons: particles without charge Electrons: negatively charged particles Ions: electrically charged atoms, molecules, particles: \*cations (+) due to electron loss \*anions (--) due to electron gain \*electrolyte: free ions present in solvent **Chemical Reactions:** Synthesis (dehydration synthesis): Formation of a larger molecule from smaller ones, Removal of H2O, Endergonic: Requires energy Hydrolysis: Breakdown of large molecules, Requires H2O, Exergonic: Gives off energy Redox (reduction--oxidation): Reduction: Gain of electrons Oxidation: Loss of electrons Simultaneous electron transfer **Compounds:** Hydrophilic: water-soluble (water-loving) Hydrophobic: insoluble in water (water-repelling) \*Inorganic: does not contain carbon (Except CO & CO2) e.g. acids, bases, salts (dissolve in water & do not release hydrogen or hydroxyl ions) & water \*Organic: contains carbon & hydrogen **Organic Compounds:** Carbohydrates, Proteins, Lipids: fats and oils, Nucleic Acids: Pentose sugar, Phosphate, Nitrogen base \*Purines: Adenine (A) and guanine (G) \*Pyrimidines: Cytosine (C), thymine (T), and uracil (U) \*DNA: Deoxyribonucleic acid (storage of genetic information) \*RNA: Ribonucleic acid \*ATP: Cell energy source **Carbohydrates: Monosaccharides**: glucose, fructose(fruit sugar), galactose **Disaccharides**: 1- Sucrose( table sugar, sweeteners) 2- Maltose 3- Lactose (milk sugar) **Polysaccharides**: 1- Glycogen( storage form of sugar in animals) 2- Starch( storage form of sugar in plants) **Solution** a mixture of one or more substances called solutes, dispersed in a dissolving medium called a solvent **\*Isotonic Solution:** solute concentration equal inside and outside of cell **\*Hypertonic Solution:** solute concentration outside the cell is higher than inside the cell **\*Hypotonic Solution:** solute concentration outside the cell is lower than inside the cell **Body Fluids** make 60% of total body weight 2/3 in intracellular fluid {40%} 1/3 in extracellular fluid {20%} In the ECF: \* ¾ in the interstitial fluid {15%} \* ¼ in plasma {5%} {intravascular} **Electrolytes:** In ECF: \*Na+ is the main cation \*Chloride is the main anion In ICF: \*K+ is the main cation \*Phosphate is the main anion **pH Scale** Measures the alkalinity or acidity of a solution Based on the hydrogen ion concentration pH scale runs from 0 to 14 Pure H2O is neutral: pH of 7 Substances that dissociate in water can form acids, bases, or salts **Acids**: pH less than 7 (release hydrogen ions) **Bases:** pH greater than 7(release hydroxyl ions **Microbiological Laboratory Techniques** **A culture**: \*pure (has one type of organisms) \*mixed (has two or more species) **Culture Media:** Classified based on: **A- Physical state:** **I- Liquid Media:** (broth): Water-based solutions **II- Semisolid Media:** Clot at room temperature **III- Solid Media:** Solid at room temperature, becomes liquid at boiling temperature of water **B- Chemical Composition:** **I- Chemically defined (synthetic):** Contain pure compounds Chemical content specified by exact formula **II- Complex media (nonsynthetic):** One or more components is not chemically defined Cannot be represented by an exact chemical formula **C- Functional Types of Media:** **I- General purpose media**: For microbes that do not have special growth requirements **Nutrient agar** **Trypticase soy agar (TSA)** **II- Enriched media:** Contain complex organic substances, such as blood **Blood agar:** detects the ability to produce hemolysins **Chocolate agar**: for respiratory bacteria **Thayer-Martin agar**: for Neisseria **III- Selective media:** Contain one or more agents that inhibit the growth of a certain microbe Favor or select a certain microbe and allow it to grow **Phenylethyl alcohol agar:** Selective for gram-positive bacteria Inhibits growth of gram-negative bacteria **IV- Differential media:** **\*MacConkey agar** (selective & differential): contains neutral red (yellow dye when neutral becomes red when acidic by E. coli which is lactose fermenter, Salmonella on the other hand is non lactose fermenter) **\*Mannitol salt agar** (selective & differential): its 7.5% NaCl inhibits most organisms except staphylococcus (can stand high salt) **Live Media:** \- Certain bacteria require host animals to grow \- Mycobacterium Leprae on mice footpad **Basic procedures to examine & characterize microbes (The Five I's):** **1- Inoculation:** Into a medium **2- Incubation:** Incubator temperature is generally between 20˚ C and 40˚ C **3- Isolation** \- Spread Plate: Used to quantify the number of bacteria in a solution Colonies are evenly distributed over the agar surface and are easily counted **4- Inspection:** Colonies are observed macroscopically Growth Patterns in Broths Bacteria grown in broth exhibit the following patterns **Pellicle:** a thick growth at the top of the tube **Sediment** at the bottom of the tube **Turbid** growth throughout the tube **5- Identification:** Determination of the type of microbe Identification Techniques: A- Morphological characteristics B- Physiological characteristics C- Biochemical characteristics