Summary Notes: Biological Molecules

Carbohydrates

• Monosaccharides: simplest form of carbohydrates, e.g., glucose, fructose.
• Disaccharides: formed from two monosaccharides, e.g., sucrose (glucose + fructose).
• Polysaccharides: complex carbohydrates, e.g., starch, glycogen.

Key Functions:

• Energy provision.
• Structural roles in cells.

Proteins

• Made of amino acids linked by peptide bonds.
• Structure Levels:
  • Primary: sequence of amino acids.
  • Secondary: alpha-helix and beta-pleated sheet formations.
  • Tertiary: 3D folding due to side chain interactions.
  • Quaternary: multiple polypeptides interacting.

Enzymes:

• Biological catalysts that speed up reactions.
• Specificity: active site matches substrate.

Lipids

• Composed of glycerol and fatty acids.
• Types:
  • Triglycerides: energy storage.
  • Phospholipids: structural component of cell membranes.
  • Steroids: signaling molecules, e.g., hormones.

Functions:

• Energy storage.
• Structural components of cell membranes.
• Insulation and protection.

Nucleic Acids

• DNA: stores genetic information; double helix structure.
• RNA: involved in protein synthesis; single-stranded.

Key Processes:

• Replication: copying DNA for cell division.
• Transcription: RNA synthesis from a DNA template.
• Translation: Protein synthesis from RNA.

Water

• Essential for life; acts as a solvent and medium for chemical reactions.
• Properties:
  • Cohesion and adhesion.
  • High specific heat capacity.
  • Role in temperature regulation.

These notes summarize the fundamental concepts of biological molecules as required for an A-level Biology course. The key focus areas include the structure, types, and functions of carbohydrates, proteins, lipids, nucleic acids, and the essential role of water in biological systems.