Overview
This lecture covers foundational concepts in biology and chemistry, including the characteristics of life, themes of biological organization, properties of water, the basics of carbon chemistry, and types of chemical bonds and interactions relevant to living systems.
Characteristics and Themes of Life
- Life is defined by organization, metabolism, development, reproduction, evolution, and response to stimuli.
- Emergent properties arise from interactions at higher organizational levels (e.g., cells to tissues).
- Reductionism analyzes parts; systems biology studies interactions among parts.
- Organisms interact through ecological relationships like predation and mutualism.
- Structure is closely related to function (e.g., bird wing anatomy supports flight).
- All organisms are made of cells, which are the basic units of life (cell theory).
- DNA is the universal genetic material, underlying inheritance and continuity.
Energy, Evolution, and Scientific Process
- Producers use light or chemical energy; consumers eat other organisms for energy.
- Energy flows through ecosystems; matter cycles within them.
- Negative feedback reduces a process (e.g., insulin lowers blood sugar); positive feedback amplifies it (e.g., childbirth).
- Evolution by natural selection leads to adaptation and diversity.
- Taxonomic hierarchy: Domain → Species (Bacteria, Archaea, Eukarya).
- The scientific method involves hypothesis-driven experiments, reasoning (inductive/deductive), and distinguishes science from technology.
Chemical Bonds and Interactions
- Electronegativity is an atom's ability to attract electrons; differences determine bond polarity.
- Covalent bonds involve shared electrons: polar (unequal) or non-polar (equal).
- Non-covalent bonds (ionic, hydrogen, van der Waals, hydrophobic interactions) are weaker and key to biological processes.
Water and Its Biological Roles
- Water’s polarity and hydrogen bonding give rise to cohesion, adhesion, high heat capacity, heat of vaporization, and expansion upon freezing.
- Water acts as a solvent, enabling solution formation and hydration shells.
- pH measures [H⁺] concentration; buffers resist pH changes.
- Acidification results from excess CO₂ or pollutants, impacting ecosystems.
Carbon and Organic Chemistry
- Carbon forms four covalent bonds, enabling diverse molecular structures (chains, rings, branches).
- Vitalism was disproved by the lab synthesis of organic molecules (e.g., urea, Miller-Urey experiment).
- Isomers have the same formula but different structures: structural, cis-trans, enantiomers.
- Functional groups (e.g., hydroxyl, carboxyl, amino) determine chemical reactivity.
Electrostatic (Ionic) Interactions
- Electrostatic interactions are attractions between oppositely charged ions, described by Coulomb’s law.
- Their strength depends on charge, distance, and the surrounding medium.
- Biological relevance: salt bridges in proteins, DNA-histone binding, enzyme active sites.
Key Terms & Definitions
- Emergent Properties — New attributes from interactions among system parts.
- Reductionism — Studying systems by breaking them into components.
- Systems Biology — Examining the interactions within biological systems.
- Electronegativity — Atom's tendency to attract electrons in a bond.
- Covalent Bond — Chemical bond involving shared electrons.
- Non-covalent Bond — Weaker bonds like ionic, hydrogen, van der Waals, and hydrophobic.
- Isomer — Molecules with same formula but different structure.
- Functional Group — Specific group of atoms conferring chemical properties.
- Buffer — Substance that stabilizes pH in solution.
Action Items / Next Steps
- Review chapter readings on biological organization, water properties, and carbon chemistry.
- Practice identifying types of chemical bonds and functional groups.
- Complete assigned questions regarding emergent properties and feedback mechanisms.