Monomers and Polymers, Proteins, and Cells

Monomers and Polymers

  • Carbon forms long chains, leading to macromolecules (e.g., starch, proteins, DNA).

  • Polymers consist of repetitive subunits called monomers (e.g., starch is 3,000 glucose units).

  • Polymerization: Joining of monomers through dehydration synthesis, producing water and forming covalent bonds.

  • Hydrolysis: Opposite process of breaking polymers by adding water, essential in chemical digestion.

Proteins

  • Proteins, derived from 'proteios', are vital molecules in the body.

  • Amino Acids: Building blocks of proteins; 20 types defined by distinct R groups (e.g., polar/nonpolar).

  • A peptide is formed from two or more amino acids by peptide bonds.

  • Protein Structure Levels:

    • Primary: Sequence of amino acids.

    • Secondary: Coiling (alpha helix) and folding (beta sheet) held by hydrogen bonds.

    • Tertiary: 3D shape due to R group interactions, essential for function.

    • Quaternary: Assembly of polypeptide chains (e.g., hemoglobin).

  • Denaturation: Loss of protein function due to shape alteration from extreme conditions.

  • Conjugated Proteins: Proteins with non-amino acid components (e.g., heme in hemoglobin).

Protein Functions

  • Diverse functions:

    • Structure: Keratin (nails/hair) and collagen (skin/bones).

    • Communication: Hormones and receptors (e.g., insulin).

    • Membrane Transport: Channel proteins and pumps (e.g., sodium-potassium pump).

    • Catalysis: Enzymes facilitating metabolic reactions.

    • Recognition and Protection: Antibodies and clotting proteins.

    • Movement: Motor proteins enabling cellular movement (e.g., muscle contraction).

    • Cell Adhesion: Binding of cells to each other facilitated by proteins.