Matter, Ions, and Chemical Reactions

• Matter occupies space, has mass, and exists as solid, liquid, or gas, composed of elements.
• Chemical compounds are combinations of elements.
• Atoms are the smallest particles of an element.
• The atomic nucleus contains protons and neutrons.
• Protons are positively charged particles.
• Neutrons are particles without charge.
• Electrons are negatively charged particles.
• Ions are electrically charged atoms, molecules, or particles.

Ions

• Cations are positive ions, resulting from electron loss.
• Anions are negative ions, resulting from electron gain.
• Electrolytes are free ions present in a solvent.

Chemical Reactions

• Synthesis (dehydration synthesis) forms a larger molecule from smaller ones, removing H2O and requiring energy (endergonic).
• Hydrolysis breaks down large molecules, requires H2O, and releases energy (exergonic).
• Redox (reduction-oxidation) involves simultaneous electron transfer.
  • Reduction is the gain of electrons.
  • Oxidation is the loss of electrons.

Compounds

• Hydrophilic compounds are water-soluble (water-loving).
• Hydrophobic compounds are insoluble in water (water-repelling).

Inorganic Compounds

• Generally do not contain carbon (except CO and CO2).
• Examples include acids, bases, and salts.
• Dissolve in water and don't release hydrogen or hydroxyl ions.

Organic Compounds

• Contain carbon and hydrogen.
• Include carbohydrates, proteins, lipids (fats and oils), and nucleic acids.
• Nucleic acids consist of pentose sugar, phosphate, and a nitrogen base.
  • Purines: Adenine (A) and guanine (G).
  • Pyrimidines: Cytosine (C), thymine (T), and uracil (U).

Nucleic Acids

• DNA (deoxyribonucleic acid) stores genetic information.
• RNA (ribonucleic acid).
• ATP is a cell energy source.

Carbohydrates

• Monosaccharides: glucose, fructose (fruit sugar), galactose.
• Disaccharides:
  • Sucrose (table sugar, sweeteners).
  • Maltose.
  • Lactose (milk sugar).
• Polysaccharides:
  • Glycogen (storage form of sugar in animals).
  • Starch (storage form of sugar in plants).

Solutions

• A solution is a mixture of solutes dispersed in a solvent.
  • Isotonic Solution: solute concentration is equal inside and outside of the 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

• Body fluids make up 60% of total body weight.
  • 2/3 is intracellular fluid (40%).
  • 1/3 is extracellular fluid (20%).
• In the ECF:
  • ¾ is in the interstitial fluid (15%).
  • ¼ is 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 hydrogen ion concentration.
• Ranges from 0 to 14.
• Pure water is neutral with a pH of 7.
• Acids have a pH less than 7, and release hydrogen ions.
• Bases have a pH greater than 7, and release hydroxyl ions.
• Substances that dissociate in water can form acids, bases, or salts.

Microbiological Lab Techniques

• A culture can be pure (one type of organism) or mixed (two or more species).

Culture Media

• Media are classified based on physical state, chemical composition, and function.
• Physical state:
  • Liquid media (broth) are water-based solutions.
  • Semisolid media clot at room temperature.
  • Solid media are solid at room temperature and liquefy at boiling temperature.
• Chemical Composition
  • Chemically defined (synthetic) media contain pure compounds with specified chemical content and exact formula.
  • Complex media (nonsynthetic) contain one or more components that are not chemically defined, and cannot be represented by an exact chemical formula.
• Functional Types of Media:
  • General purpose media are for microbes without special growth requirements (e.g., nutrient agar, trypticase soy agar).
  • Enriched media contain complex organic substances, such as blood.
    • Blood agar detects the ability to produce hemolysins.
    • Chocolate agar is for respiratory bacteria.
    • Thayer-Martin agar is for Neisseria.
  • Selective media contain agents that inhibit certain microbes, favoring the growth of others.
    • Phenylethyl alcohol agar is selective for gram-positive bacteria and inhibits gram-negative bacteria.
  • Differential media are used to distinguish between organisms.
    • 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): 7.5% NaCl inhibits most organisms except staphylococcus, which can stand high salt.
  • Live Media:
    • Certain bacteria require host animals to grow.
    • Mycobacterium Leprae grows on mice footpad.

Basic Procedures ("Five I's")

• Inoculation: introduction of a sample into a medium.
• Incubation: maintaining the inoculated media at optimal temperature (generally between 20°C and 40°C).
• Isolation: separating individual colonies.
  • Spread plate: quantifies bacteria in a solution, colonies evenly distributed for easy counting.
• Inspection: observing colonies macroscopically and growth patterns in broths.
  • Pellicle: a thick growth at the top of the tube
  • Sediment at the bottom of the tube
  • Turbid growth throughout the tube
• Identification: determining the type of microbe.
  • Identification techniques: morphological, physiological, and biochemical characteristics.

Specimen Preparation

• Wet mounts: live samples placed on slides.
• Smear: a thin film of a solution of microbes on a slide.
• Heat fixation: attaches microbes to the slide and kills them.

Staining

• Negative stain:
  • Indirect staining process
  • Does not require fixation of smear
  • Acidic stains (e.g., India ink or nigrosin) create a dark background against the organism.
  • Useful for staining spirochetes, yeast, and bacterial capsules.

Simple Stain

• Single stain applied to specimen after fixation
  • E.g., Methylene blue, Crystal violet

Differential Stains

• More complex than simple stains.
• Use more than one stain to differentiate cellular components.
• Allow differentiation between bacterial species.
  • Gram stain: differentiates between gram-positive (purple/blue) and gram-negative (red/pink) bacteria.
  • Acid-fast stain: uses carbolfuchsin and acid-alcohol.
    • Acid-fast bacteria (with mycolic acid in cell wall) appear red.
    • Nonacid-fast bacteria (without mycolic acid) appear blue after methylene blue treatment.
  • Wright stain: for staining blood smears.

Overview of matter's composition and states (solid, liquid, gas), focusing on elements, compounds, and atoms. Explanation of ions (cations, anions) and electrolytes. Discussion of chemical reactions: synthesis (dehydration synthesis), hydrolysis, and redox (reduction-oxidation).