Macromolecules Notes

Monomers and Polymers

  • Monomers are the building blocks of polymers.
  • Dehydration Synthesis:
    • A monomer forms a covalent bond with another monomer.
    • Releases a water molecule (H_2O).
    • Carbohydrates, nucleic acids, and proteins all contain multiple types of monomers.
    • Composition and sequence are important to function.
  • Hydrolysis:
    • A bond is broken by adding a water molecule.
    • One molecule gains "H," and the other gains "OH."
    • Generally releases energy.

Carbohydrates

  • Composed of Carbon, Hydrogen, and Oxygen.
  • Monosaccharides:
    • Simple sugars containing 3-7 carbon atoms.
      • Examples: glucose, fructose, galactose.
      • These are isomers of each other, differing in the organization of their atoms.
  • Disaccharides:
    • Form when two monosaccharides bond via dehydration synthesis.
      • Examples: lactose, maltose, sucrose.
  • Polysaccharides:
    • Long chains of monosaccharides linked by glycosidic bonds.
      • The chain may be branched or unbranched.
      • Examples: starch, glycogen, cellulose, chitin.
  • Starch:
    • Stored form of sugars in plants.
  • Glycogen:
    • Storage form of glucose in humans.

Protein Structure

  • Primary Structure:
    • Sequence of amino acids.
  • Secondary Structure:
    • Due to interactions of the peptide backbone.
    • Beta-pleated sheets: hydrogen bonding.
      • Parallel: backbones interact and sequence matches.
      • Anti-parallel: opposite sequences & backbones interact.
    • Alpha helix: hydrogen bonds between different layers of the helix.
  • Tertiary Structure:
    • Due to interactions of side chains.
      • Hydrophobic and hydrophilic regions attract each other.
      • Hydrogen bonds might form.
  • Quaternary Structure:
    • Arrangement of multiple chains together (more than one polypeptide).

Triglycerides (Fats)

  • Fatty acids:
    • Carbon chains (hydrophobic) with an acidic carboxyl group.
  • Glycerol:
    • Can bond with 3 fatty acids through dehydration, resulting in a triglyceride.
    • Ester bonds are formed.
  • Saturated Fat:
    • Saturated by hydrogen.
    • Solid at room temperature.
    • Unhealthy (e.g., butter).
    • Dense.
    • No double bonds.
  • Unsaturated Fat:
    • Less hydrogen.
    • Liquid at room temperature.
    • Kinks formed making them less dense.
    • Healthier (e.g., oils).

Macro Building Blocks, Functions, and Examples

  • Carbohydrates:
    • Building Blocks: Monosaccharides (simple sugars)
    • Functions: Quick/short-term energy source, source of dietary fiber.
    • Examples: Glucose, sucrose, starch, glycogen.
  • Lipids (Fats, Phospholipids):
    • Building Blocks: Fatty acids or long-chain fatty acids and Glycerol.
    • Functions: Long-term energy, make up biological membranes.
    • Examples: Waxes, oils, grease, steroids.
  • Proteins:
    • Building Blocks: Amino acids.
    • Functions: Provide cell structure, send chemical signals, speed up chemical reactions (enzymes), antibodies.
    • Examples: Keratin, hormones, enzymes, antibodies.
  • Nucleic Acids:
    • Building Blocks: Nucleotides.
    • Functions: Store & pass on genetic information.
    • Examples: DNA, RNA.

Nucleic Acids

  • DNA:

    • Found in the nucleus in eukaryotes.
      • Organized into chromosomes.
        • DNA is broken up into long linear pieces.
        • Chromosomes contain tens of thousands of genes.
    • Located in the nucleoid of prokaryotes.
      • Chromosomes are smaller & often ring-shaped.

  • Monomers: Nucleotides.

    • When combined, the resulting chain is called a polynucleotide.
    • Made up of:
      • Nitrogen-containing ring (Nitrogenous base).
      • Five-carbon sugar.
      • At least one phosphate group.

  • Purines: Adenine (A) & Guanine (G) - Two rings.

  • Pyrimidines: Thymine (T), Uracil (U), & Cytosine (C) - Single ring.

  • DNA's Sugar: Deoxyribose - The 2nd carbon has a hydrogen.

  • RNA's Sugar: Ribose - The 2nd carbon has a hydroxyl group.

  • Polynucleotide Chain:

    • Has directionality.
      • 5' - Phosphate group.
      • 3' - Hydroxyl of the last nucleotide.

  • DNA sequences written in 5' to 3' direction.

  • DNA Chains:

    • Found in a double helix; two complementary chains stuck together.
      • Sugar-phosphate backbone.
      • Bases in the interior, bound to each other by hydrogen bonds.
      • Two strands have opposite directionality - anti-parallel orientation.

  • RNA:

    • Single-stranded.
    • mRNA: An intermediate between a protein-coding gene & its protein product.
    • rRNA: Helps accelerate chemical reactions & helps mRNA bind to the right spot.
    • tRNA: Brings amino acids to the ribosome.
    • RNA is involved in protein synthesis & gene regulation.