BIOL 170: The Chemistry of Life

Page 1: Introduction to Atoms

• Atoms

  • Smallest unit of matter.

  • Composed of:

    • Protons

    • Electrons

    • Neutrons

  • A human cell contains approximately (10^{12}) atoms.

• Atoms vs. Elements

  • Element: A substance with only one kind of atom.

  • Atomic Number: Number of protons.

  • Average Atomic Mass: Sum of protons and neutrons.

Page 2: The Periodic Table and Electron Configuration

• Periodic Table

  • Number of possible elements is increased by isotopes.

• Protons and Electrons

  • Determine interactions between elements.

  • Electrons are located in orbitals.

  • Example: An atom with 11 protons, 12 neutrons, and 11 electrons.

• Orbitals and Valence Shells

  • Limited capacity; filled into valence shells based on electron number.

  • Valence Shell: Outermost shell; follows the octet rule for stability.

Page 3: Chemical Bonding

• Types of Bonding

  • Creates atomic stability through:

    1. Electron transfer (Ionic bonding)

    2. Electron sharing (Covalent bonding)

    3. Electronegative attraction (Polarity)

• Ionic Bonding

  • Involves electron transfer between two atoms.

  • Occurs when electronegativity difference is high.

  • Cation: Positively charged (loses electrons).

  • Anion: Negatively charged (gains electrons).

  • Forms "salt".

• Covalent Bonding

  • Atoms share electrons to achieve stability.

  • Bonds can be single, double, or triple.

Page 4: Variations in Electron Sharing

• Non-Polar Covalent Bonds

  • Equal sharing of electrons between nonmetals with similar electronegativity.

• Polar Covalent Bonds

  • Unequal sharing of electrons leads to partial charges.

• Hydrogen Bonds

  • Weak attractions between dipoles.

  • Basis for surface tension in water.

• Hydrophilic and Hydrophobic Interactions

  • Facilitate chemical bonding.

Page 5: Compounds of Life

• Types of Compounds

  • Organic

  • Inorganic

• Water

  • Inorganic, makes up 60-80% of human body mass.

  • Universal solvent; interacts via hydrogen bonding.

  • Properties:

    1. High specific heat

    2. High heat capacity

    3. High heat of vaporization

    4. Cohesion

    5. Surface tension

• Carbon

  • Can form four bonds with different elements.

  • Capable of single and double bonds.

Page 6: Organic Molecules

• Characteristics of Living Beings

  • Common set of molecules for cell formation.

  • Respond to environmental stimuli.

  • Carry out metabolism.

  • Grow and develop.

  • Maintain homeostasis.

  • Reproduce and direct heredity.

  • Adapt and evolve.

• Types of Organic Molecules

  • Composed of monomer subunits:

    • Carbohydrates

    • Amino Acids

    • Fatty Acids

    • Nucleotides

  • Include:

    • Polysaccharides

    • Proteins

    • Phospholipids/Fats

    • Nucleic Acids

Page 7: Carbohydrates

• Composition

  • Made of carbon, hydrogen, and oxygen.

• Functions

  • Energy storage and transport.

  • Structural support.

  • Cellular identity.

• Types of Carbohydrates

  • Monosaccharides: Simple sugars (3 to 7 carbons).

  • Disaccharides: Two monosaccharides joined by dehydration.

  • Oligosaccharides: Fewer than 12 monosaccharides.

  • Polysaccharides: More than 12 monosaccharides.

    • Examples:

      • Starch (energy storage in plants)

      • Glycogen (energy storage in animals)

      • Cellulose (structural support in plants; indigestible).

Reminders

• Surveys and sign-ups.

• Personal introduction and honor code (not extra credit).

• Lab 1 assignment due 1 hour before next week’s lab.

• Lab 2 pre-quiz due 1 hour before next week’s lab.