Chemistry of Life: Atoms and Water Properties

Chemistry of Life

• Atoms are composed of protons, neutrons, and electrons
• Protons have a positive charge, neutrons are neutral, and electrons have a negative charge
• The number of protons determines the identity of an atom
• The number of electrons determines the reactivity of an atom
• Atoms are composed of a nucleus containing protons and neutrons, with electrons orbiting the nucleus.
• Water molecules are polar, having a slightly positive hydrogen end and a slightly negative oxygen end.
• Hydrogen bonds form between the slightly positive hydrogen of one water molecule and the slightly negative oxygen of another.
• Adhesion is the attraction between water molecules and other substances
• Cohesion is the attraction between water molecules
• Polarity is a molecule's unequal distribution of charge
• Surface tension is the tendency of liquid surfaces to resist external forces, due to cohesive forces
• Capillary action is the movement of water within spaces of narrow diameter in opposition to external forces like gravity
• Water transports nutrients and dissolved minerals up plants and through tissues via adhesion, cohesion, and the effect of capillary action.

Cell Biology

• Eight qualities of something being alive
• Cell Theory:
  • All living things are made of cells
  • Cells are the basic units of structure and function in living things
  • New cells are created from existing cells
• Prokaryotic cells lack a nucleus and membrane-bound organelles
• Eukaryotic cells contain a nucleus and membrane-bound organelles
• All cells have a cell membrane which is a selectively permeable; the cell membrane is important for active and passive transport

Cell Transport

• Passive transport moves substances across a membrane without energy input.
• Active transport moves substances across a membrane with energy input
• Types of Passive transport include simple diffusion and facilitated diffusion
• Tonicity describes the relative concentration of solutes in two solutions
• Hypertonic solution has a higher solute concentration
• Hypotonic solution has a lower solute concentration
• Isotonic solutions have the same solute concentration
• Osmosis is the movement of water across a selectively permeable membrane from a region of high water concentration to a region of low water concentration
• Diffusion is the passive movement of molecules from an area of high concentration to an area of low concentration
• Concentration gradient is a difference in the concentration of a substance across a distance
• Active transport is the movement of a substance across a membrane against its concentration gradient, requiring energy input.

Photosynthesis & Cellular Respiration

• Enzymes are proteins that speed up chemical reactions
• Factors like temperature, pH, and substrate concentration affect enzyme reaction rates
• ATP is the primary energy currency of cells
• Photosynthesis is the process by which plants convert light energy into chemical energy
• Cellular respiration is the process by which organisms convert chemical energy into usable energy for cellular processes
• Photosynthesis equation: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
• Cellular respiration equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP

Cell Division

• Cells maintain a small size to maximize surface area-to-volume ratio for efficient nutrient and waste exchange .
• Interphase is the stages before mitosis and includes G1, S, and G2 phases.
• Mitosis is a type of cell division resulting in two identical daughter cells
• Stages of Mitosis are Prophase, Metaphase, Anaphase, and Telophase.
• Human cells contain 46 chromosomes.
• Gametes, or sex cells, contain 23 chromosomes.

Mitosis vs. Meiosis

• Mitosis is cell division used for growth and repair, maintaining ploidy
• Meiosis is cell division used for sexual reproduction, reducing ploidy
• Mitosis produces two identical diploid daughter cells
• Meiosis produces four genetically unique haploid daughter cells
• Types of cells, purpose of division, ploidy