Lecture 1.2: The Chemical Foundation of Life

Introduction

• Course: BISQUE 130
• Chapter 2: Chemical Foundation of Life
• Purpose: Establish a baseline understanding of chemical principles foundational to biology.
• Background: No prerequisite in chemistry required, but useful if known.

Key Concepts

Matter

• Definition: Anything that has mass and occupies space.
• Includes: Atoms and subatomic particles.

Elements

• Definition: Unique substances, 118 in total, with specific properties and proton numbers.
• Periodic Table: Organizes elements by atomic number and properties.

Atomic Structure

• Components of Atoms:
  • Protons: Positively charged, located in the nucleus, mass of 1 AMU, define element's identity.
  • Neutrons: Neutrally charged, located in the nucleus, mass of 1 AMU, contribute to isotopes.
  • Electrons: Negatively charged, orbit nucleus, negligible mass.

Importance of Protons

• Define element: Number of protons determines atomic number and element (e.g., 1 proton = Hydrogen).

Neutrons and Isotopes

• Isotopes: Variants of elements based on neutron count (e.g., Carbon-12, Carbon-13, Carbon-14).

Electrons

• Characteristics: Orbit nucleus, lack functional mass, balance with protons for charge neutrality.
• Stability: Atoms are most stable with specific electron counts (2, 10, 18).

Chemical Bonds

• Purpose: Achieve electron stability by forming bonds.

Covalent Bonds

• Definition: Sharing of electron pairs between atoms.
• Types:
  • Single: One pair shared (e.g., H-H).
  • Double: Two pairs shared (e.g., O=O).
  • Triple: Three pairs shared (e.g., N≡N).
• Polarity: Unequal sharing creates polar bonds (e.g., H2O's O-H bond).

Ionic Bonds

• Definition: Attraction between oppositely charged ions (e.g., Na⁺ and Cl⁻).
• Formation: Through loss/gain of electrons, creating charged ions.

Hydrogen Bonds

• Definition: Attraction between a partially positive hydrogen and a partially negative atom.
• Strength: Weakest type of bond but significant in large numbers.

Water and its Biological Importance

Properties of Water

• Solvent Ability: Dissolves ionic and polar substances due to partial charges.
• Adhesion and Cohesion:
  • Cohesion: Water sticks to itself (surface tension).
  • Adhesion: Water sticks to other materials (capillary action).
• Ionization: Water dissociates into H⁺ and OH⁻ ions, crucial for chemical reactions.

Hydrophilic and Hydrophobic Substances

• Hydrophilic: Dissolve in water (e.g., NaCl, glucose).
• Hydrophobic: Do not dissolve (e.g., oils).

Relevance of Water in Biology

• Search for Extraterrestrial Life: Water's properties make it essential for life, hence its importance in astrobiology.

Additional Notes

• Organic Molecules: Defined as carbon-containing, except CO2.

These notes summarize the core points of the lecture, providing a foundation in understanding the chemical principles key to biological processes. Further exploration of the remaining chapter will continue in subsequent lectures.