Biology Chapter on Large Biological Molecules

Large Biological Molecules

• Four main classes: carbohydrates, lipids, proteins, and nucleic acids.
• Polymers consist of smaller recurring units called monomers.

Polymerization and Hydrolysis

• Polymers are formed through dehydration reactions.
• Hydrolysis is the reaction that breaks down polymers into monomers.

Organic Compounds

• Carbon-based molecules are referred to as organic compounds.

Carbohydrates

• Simplest carbohydrates are monosaccharides, serving as building blocks for larger carbohydrates.
• Monosaccharide formula: CH2O or (CH2O)n; example: glucose (C6H12O6).
• Disaccharides are sugars formed from two monosaccharides.
• Polysaccharides are long chains of monosaccharides linked by dehydration reactions, such as starch, glycogen, and cellulose.
• Starch acts as a storage polysaccharide in plants, while glycogen is the animal equivalent.
• Cellulose provides structural support in plant cell walls.

Lipids

• Lipids are hydrophobic compounds, meaning they do not mix with water.
• Fats are large lipids composed of glycerol and fatty acids, primarily serving as energy-storage molecules.
• Saturated fats contain the maximum number of hydrogen atoms and are solid at room temperature; examples include butter.
• Unsaturated fats have fewer hydrogen atoms due to double bonds, remaining liquid at room temperature; examples include oils like olive oil and corn oil.
• Important lipids with various functions include phospholipids and steroids.

Proteins

• Proteins are polymers made from amino acid monomers.
• Structural proteins are found in hair, skin, and muscle.
• Polypeptides are chains of amino acids that fold into functional proteins.
• Denaturation occurs when polypeptide chains unravel, losing their specific shape and function.

Summary of Monomers and Functions

• Carbohydrates:
  • Monomer: monosaccharide
  • Function: short-term energy storage, plant structure
  • Example: sucrose, starch, cellulose, glycogen
• Lipids:
  • Monomer: fatty acids
  • Function: long-term energy storage
  • Example: triglycerides (fats), phospholipids, steroids
• Proteins:
  • Monomer: amino acids
  • Function: structural roles, enzymes
  • Example: hair, skin, muscles, catalase