BSCI201 1.30

Atomic Structure

  • Electrons in Orbits

    • First orbit: up to 2 electrons

    • Second orbit: up to 8 electrons

    • Third orbit: can carry 18 electrons but is stable with 8 (octet rule)

  • Structure of an Atom

    • Protons are located in the atomic nucleus and have a positive charge.

    • Electrons orbit around the nucleus and have a negative charge.

Example of Sodium Chloride Formation

  • Sodium (Na)

    • Atomic number: 11

    • Configuration: 2, 8, 1 (2 in the first, 8 in the second, 1 in the third)

    • Can lose 1 electron to achieve stability or gain 7 additional electrons, but losing one is more favorable

  • Chloride (Cl)

    • Atomic number: 17

    • Configuration: 2, 8, 7

    • Gains 1 electron from sodium to achieve one stable outer shell (now has 8) forming Cl- ion

Chemical Reactions

  • Consist of bonds being formed or broken between atoms.

  • Types of bonds:

    • Ionic bonds: One atom donates an electron to another.

    • Covalent bonds: Atoms share electrons. Can be:

      • Nonpolar: Electrons are shared equally.

      • Polar: Electrons are shared unequally, leading to slight charges.

  • Hydrogen bonds: Formed when a hydrogen atom covalently bonded to one atom is attracted to another atom.

Importance of Water

  • Composition: H2O, where hydrogen forms polar covalent bonds with oxygen.

  • Role in Body:

    • Makes up about 70% of cell volume

    • High heat of capacity aids in thermoregulation

pH and Buffers

  • Blood pH is maintained between 7.35 - 7.45 for enzymatic reactions.

  • pH is inversely related to hydrogen ion (H+) concentration.

    • High H+ = Low pH (more acidic)

    • Low H+ = High pH (more alkaline)

  • Buffers: Resist pH changes by managing H+ concentrations and maintaining homeostasis.

Salts and Ionic Compounds

  • Example: Sodium Chloride (NaCl)

    • Ionic compound formation occurs when sodium donates an electron and chlorine accepts it, creating Na+ and Cl- ions.

  • Calcium ion is crucial for many biological reactions.

Carbohydrates and Lipids

  • Carbohydrates:

    • Monosaccharides (e.g., glucose) and polysaccharides are key energy sources.

    • Isomers: Different arrangements of the same molecular formula.

  • Lipids:

    • Classification:

      • Saturated fats: Solid at room temperature; found in animal products.

      • Unsaturated fats: Liquid at room temperature; found in plant oils.

Cholesterol and Lipoproteins

  • Low-Density Lipoproteins (LDL): Associated with "bad" cholesterol; can form plaque in arteries.

  • High-Density Lipoproteins (HDL): Higher protein content, helps remove cholesterol from bloodstream.

Amino Acids

  • Structure: Have both amino (base) and carboxyl (acid) groups; considered amphoteric (can act as acid or base).

  • Protein structures in human body are determined by the sequence of amino acids.

    • Mutations in amino acid sequence can lead to diseases like sickle cell anemia.

  • Protein Folding:

    • Primary structure forms alpha helices and beta-pleated sheets which are crucial for the functionality of proteins.

    • Can influence enzyme activity and interactions.