Unit One: Biological Molecules Overview

I. Properties of Water (H₂O)

  • Structure: Polar molecule with hydrogen bonding

  • Key Properties:

    • Cohesion, Adhesion, Surface Tension

    • High Specific Heat, High Heat of Vaporization

    • Ice is less dense than water (hydrogen bonds)

    • Excellent solvent due to polarity

  • Hydrogen Bonds:

    • Require lots of energy to change state of matter

II. Elements of Life (CHNOPS)

  • Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur

    • Major elements in biological molecules

III. Macromolecules

1. Carbohydrates

  • Made of: C, H, O

  • Function: Energy, structure

  • Monomer: Monosaccharides

  • Example: Starch, cellulose, glycogen (all made of glucose)

2. Lipids

  • Made of: C, H, O

  • Types:

    • Fats, Steroids, Phospholipids

  • Properties:

    • Nonpolar, hydrophobic

    • Saturated = no double bonds

    • Unsaturated = double bonds

  • Membranes: Phospholipids + cholesterol (fluidity)

  • Function: Energy storage, insulation, membrane structure

3. Proteins

  • Made of: C, H, O, N, S

  • Monomer: Amino acids

  • Bonds: Peptide bonds (via dehydration synthesis)

  • Structure Levels:

    • Primary: Amino acid sequence

    • Secondary: Alpha helix, beta sheets (H-bonds)

    • Tertiary: 3D folding, disulfide bridges, etc.

    • Quaternary: Multiple polypeptides

  • Function:

    • Enzymes (speed up reactions)

    • Structure, communication, transport

  • Denaturation:

    • Causes: Temp. changes, pH, salt

    • Result: Loss of shape → loss of function

  • Chaperonins: Assist protein folding

4. Nucleic Acids

  • Made of: C, H, O, N, P

  • Monomer: Nucleotide

  • Structure:

    • Sugar + phosphate + nitrogen base

    • 5' phosphate end, 3' hydroxyl end

    • DNA: A, T, G, C (double helix, antiparallel)

    • RNA: A, U, G, C

IV. Chemical Reactions

  • Dehydration Synthesis:

    • Joins monomers by removing water

  • Hydrolysis:

    • Breaks polymers by adding water

V. Membranes

  • Made of phospholipids, proteins, cholesterol

  • Features:

    • Fluidity, selective permeability

VI. Carbohydrate Isomers

  • Aldose: Contains aldehyde group

  • Ketose: Contains ketone group

  • Alpha vs. Beta Glucose:

    • Alpha: Same direction of OH groups

    • Beta: OH group flips on carbon 1