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- (<2 -> between atoms); mostly this bond; strong bio-wise

  • 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

• 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