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