Overview of Cell and Molecular Biology

  • Living Organisms: All living things, including trees, babies, and viruses, are made of cells.

  • Key Properties of Cells:

    • Acquire energy
    • Communicate
    • Reproduce
    • Respond to stimuli
    • Evolve over time

  • Chemistry Foundations: Understanding chemical reactions is crucial for studying cell and molecular biology.

  • Macromolecules: Focus on proteins, lipids, carbohydrates; their structure relates to cell function.

  • Atoms:

    • Basic unit of life
    • Composed of protons (positive), neutrons (neutral), and electrons (negative).
    • Carbon: Atomic number 6 (6 protons, 6 neutrons); mass number 12.
    • Ions: Charged atoms that gain or lose electrons, leading to positive or negative charges.

  • Isotopes: Variants of elements with different neutrons (e.g., carbon-13, carbon-14).

  • Periodic Table: Structure shows atomic number and mass; important for understanding bonding and reactions.

  • Valence Electrons: Electrons in the outermost shell determine atomic reactivity and bonding potential.

    • Example: Carbon has 4 valence electrons, allows it to make various bonds (single, double, triple).

  • Types of Bonds:

    • Covalent Bonds: Strong, formed by sharing electrons; can be nonpolar (equal sharing) or polar (unequal sharing, e.g., water).
    • Ionic Bonds: Weaker, formed by transferring electrons between atoms, resulting in charged ions (e.g., NaCl).
    • Hydrogen Bonds: Weak interactions between polar molecules; important for water properties.
    • Van der Waals Forces: Weak attractions due to transient charges in atoms.

  • Properties of Water:

    • Solvent: Excellent for polar or ionic compounds; poor for nonpolar substances (hydrophobic).
    • Cohesion: Water molecules bind together, creating surface tension.
    • Adhesion: Water molecules can bind to other substances.
    • Density: Ice is less dense than liquid water, allowing it to float.
    • High Specific Heat: Water can absorb lots of heat before increasing in temperature.

  • Acid-Base Chemistry: Water can dissociate into H+ (protons) and OH- (hydroxide), crucial for pH balance in biological systems.

  • Energy in Chemical Bonds: Energy storage in chemical bonds supports cellular functions. Strong bonds typically store less energy but are more stable than weaker bonds that store more energy.