General Chemistry

Themes in bio

  • Evolution: Living organisms are modified descendants of common ancestors and leads to unity/diversity of organisms

  • Emergence: come out from whole; whole > parts

  • Levels of organization is hierarchy

  • Methods of investigating bio: scientific method

    • Hypothesis: testable explanation for observations based on available evidence (can be falsifiable)
    • Prediction: expectations from testing hypothesis
    • Theory: broad explanation with significant support
    • Law: statement of what always occurs under certain circumstances
    • Observation -> background -> hypothesis -> prediction -> experiment -> evaluate (ask new questions, repeat/verify experiments, revise predictions)

Basic chemistry

  • Electrons: 25 of 92 elements essential to life; -1 charge; move rapidly; determine how atom interacts

    • The further they are from the nucleus, the greater potential energy (usefulness) they have.
    • When they are excited, they have a lot of potential energy that can be used to do work (such as how photons are involved in producing ATP).

  • E- shell has e- PE

  • Valence shell: outermost shell where bonds between e- form

  • Part of atom (subatomic: proton, neutron, electron)

  • Formation of molecules

    • Chemical bonds: how atoms share e-; used to drive changes in bio. mol. -> energy -> change (energy is capacity to cause change)
    • Molecules: compounds with 2+ atoms like H2O
    • Emergent properties: compounds have different prop. Than elements (Na+ and Cl- -> NaCl)

  • Chemical bonds

    • Electronegativity: affinity for e- (atom attracting e- like O2); bond determined by difference; desire to fill valence
    • Covalent: sharing e- (
    • Ionic: >2, between charged atoms (one steals e- from another); attraction between anion and cation; weak in bio terms (separate)
    • Van der Waals: interactions between molecules bc e- move constantly -> LDF and H-bonds
    • H-bonds: dipole-dipole interaction; hold H2O together (stickiness) through polarity
StrengthElectronegativityInteraction with waterintra/inter molecular
Covalent (CH4, O2, nonpolar lipids)Hard to break<2 close to 0Don’t dissolveIntra
Polar (H2O, HF)Strong< 2dissolveintra
Ionic (NaCl, Na+, Cl-)Weak>2dissolveintra
Van der Waals (DNA) LDFs, HydrogenAttractions between different moleculesH-bondsInter
  • Emergent properties of water
    • H-bonds: water is polar and bonds with other water mol.
    • Cohesive behavior
    • When H2O sticks to one another
    • Adhesion: H2O sticks to other polar things
    • Surface tension: measure of difficulty to break surface of liquid
    • Moderates temp
    • High specific heat: hard to change H2O temperature
    • High heat of vaporization: hard to change state bc water is stable
    • Expansion upon freezing
    • Ice floats: H-bonds more ordered and form air pockets; < dense than H2O (less mol. Compared to equal volume of liquid water)
    • Versatile as solvent
    • Hydrophilic: ions/salts/polar; hydrophobic: lipids/nonpolar