BIO 151 Study Guide
Topic Three: Biochemical Compounds

The Central Role of Carbon (C)

  1. Carbon can form four bonds
  2. Hydrocarbons: chains in which C's bond only to other C's or to H's.
  3. Functional groups can be added to hydrocarbons (e.g., hydroxyl group, carboxyl gp., amino gp., phosphate gp.)

 Four major classes of Biochemical Compounds

  1. Carbohydrates
    1. very important for nutrition and structural support
    2. Basic Formula 1:2:1 ratio of C:H:O (CH2O)n
    3. monomers: Monosaccharides (= "simple sugars")
    4. polymers: Polysaccharides (= "complex carbohydrates")
      1. Storage polysaccharides (e.g, starch, glycogen)
      2. Structural polysaccharides (e.g., cellulose, chiten)
  2. Lipids
    1. Long hydrocarbon chains result in hydrophobic properties
    2. Fats--used primarily for energy storage
      1. More efficient energy storage than carbohydrates
      2. Glycerol + 3 Fatty Acids = Trigylceride
      3. saturated vs. unsaturated fats
        1. most animals fats are solid at room temperature
        2. most plant fats are liquid at room temperature (called "oils")
    3. Phospholipids
      1. Glycerol + 1 phosphate gp + 2 Fatty Acids
      2. fatty acid "tails" are hydrophobic
      3. glycerol-phosphate "head" region is hydrophilic
      4. "phospholipid bilayers" form the basic framework of membranes
    4. Steroids
      1. Basic hydrocarbon skeleton of 4 rings, differing by functional gps.
      2. examples: cholesterol, sex hormones
    5. Waxes and Wax-like substances (incl. cutin and suberin)
      1. very, very long hydrocarbon chains
      2. much harder and more water resistant than fats
      3. important in water regulation in plants
    6. Chlorophylls--photosynthetic pigments
      1. porphyrin ring "head"
      2. hydrocarbon "tail"
      3. embedded within the membranes of chloroplasts
  3. Proteins
    1. many functions within the cell, organism
    2. monomers: Amino acids
    3. polymers: Polypeptides
    4. polypeptides not considered "proteins" unless functional
    5. protein function related to shape or conformation--4 levels of structure
      1. Primary--amino acid sequence
      2. Secondary--the regular 3-D shape
        1. a helices, b pleated sheets
        2. due to H bonds between amino acids
      3. Tertiary--the irregular 3-D shape
        1. due to interactions among R groups
        2. "globular" proteins
      4. Quaternary--interactions between polypeptide chains
    6. Enzymes--an example of the importance of proteins
      1. enzymes are proteins that catalyze biochemical reactions (lower EA)
      2. active site is substrate specific
      3. enzyme activity depends on 3-dimensional shape of the protein
        1. effect of temperature and pH on enzyme activity
        2. cofactors (inorganic and organic)
        3. inhibitors (competitive and non-competitive)
      4. regulation of enzymes

  4. Nucleic acids
    1. monomers: Nucleotides, each with three components
      1. phosphate group
      2. 5 carbon sugar
        1. ribose (in RNA)
        2. deoxyribose (in DNA)
      3. nitrogenous base
        1. adenine, guanine, cytosine, uracil (in RNA)
        2. adenine, guanine, cytosine, thymine (in DNA)
    2. nucleotides linked together to form a sugar-phosphate backbone
    3. RNA can form a single strand; DNA forms a double-stranded "helix"
    4. seq. of nulceotides in nucleic acids determines seq. of amino acids in proteins