63. Naturally Occurring Polymers

1. Polypeptides and Proteins

  • Monomers: Amino acids.

  • Functional Groups: Every amino acid contains two essential functional groups:

    • Amino group: NH2

    • Carboxyl group: COOH (also known as a carboxylic acid group).

  • Bonding: These molecules join through condensation reactions.

    • The OH from the carboxyl group and an H from the amino group react to form H2O.

    • The remaining carbon and nitrogen bond together to form an amide bond, amide link, or peptide bond.

  • Polypeptides vs. Proteins: A long chain of amino acids is called a polypeptide. Once it folds or combines with other chains, it is called a protein.

2. DNA (Deoxyribonucleic Acid)

  • Monomers: Nucleotides.

  • Composition: Each nucleotide contains a small molecule called a base. There are four types of bases: A, T, C, and G.

  • Structure: DNA is made of two polymer chains that link together and coil into a double helix.

  • Function: The order of the nucleotides creates the genetic code (genes) for cells.

3. Carbohydrates

  • Elements: Made only of carbon, oxygen, and hydrogen.

  • Monomers (Monosaccharides): Simple sugars like glucose and fructose.

  • Polymers (Polysaccharides): Complex carbohydrates like starch, cellulose, and glycogen.

  • Formation: Many sugar monomers combine to create these long-chain polymers.