Unit 10: Atoms, Compounds, and Microbiology

1. Basic Chemistry in Biology

• Atoms: Smallest unit of matter, made up of protons (+), neutrons (0), and electrons (-).

• Elements: Pure substances consisting of only one type of atom (e.g., Carbon, Oxygen).

• Compounds: Two or more elements chemically combined (e.g., H₂O, CO₂).

2. Chemical Reactions in Biology

• Reactants → Products (Substances change in a reaction).

• Types of reactions important in biology:

  • Synthesis: Small molecules → Larger molecules (e.g., protein formation).

  • Decomposition: Large molecules → Smaller molecules (e.g., digestion).

  • Oxidation-Reduction: Transfer of electrons (e.g., cellular respiration).

3. Water and pH

• Water’s Properties:

  • Cohesion (sticks to itself) and adhesion (sticks to other substances).

  • High heat capacity (regulates temperature).

  • Universal solvent (dissolves many substances).

• pH Scale:

  • Measures how acidic/basic a substance is (0-14).

  • Acids (0-6.9): High H⁺ concentration (e.g., stomach acid).

  • Bases (7.1-14): High OH⁻ concentration (e.g., soap).

  • Neutral (7.0): Pure water.

4. Pathogens and Bacterial Growth

• Pathogens: Microorganisms that cause disease (e.g., bacteria, viruses, fungi).

• Bacterial Growth:

  • Binary fission: Bacteria reproduce by splitting into two identical cells.

  • Growth is exponential but limited by resources, competition, and antibiotics.

5. Microbiomes and Their Role in Health

• Microbiome: Community of microorganisms living in a specific environment (e.g., gut, skin).

• Importance of microbiomes:

  • Aid in digestion and vitamin production.

  • Protect against harmful pathogens.

  • Influence immune system function.

• Disruptions (e.g., antibiotics) can lead to imbalances, causing infections or digestive issues.

6. Food Microbiology

• Role of Microorganisms in Food Production:

  • Fermentation (e.g., yogurt, cheese, bread).

  • Preservation (e.g., pickling, curing).

• Foodborne Illnesses:

  • Caused by bacteria (e.g., Salmonella, E. coli), viruses, or fungi.

  • Prevention: Proper cooking, hygiene, and refrigeration.

Connections to Previous Units:

• Chemical reactions (Unit 4) are essential for metabolism and energy production.

• Water’s role ties into environmental cycles (Unit 6).

• Microbiomes influence human homeostasis (Unit 5).