Miss Estrich's Biology: A-Level Topic 1 Overview - Biological Molecules

Introduction

• Overview of Topic 1 in A-Level Biology: Biological Molecules
• Key facts for quick revision
• Detailed explanations available in additional videos and notes
• Upcoming release of an active recall workbook

Monomers and Polymers

• Definitions:
  • Monomers: Smaller units that form larger molecules
  • Polymers: Made from many monomers bonded together
• Examples:
  • Monomers: Glucose, amino acids, nucleotides (RNA, DNA)
  • Polymers: Starch, cellulose, glycogen, proteins, DNA/RNA
• Reactions:
  • Condensation Reaction: Joins molecules, forms chemical bonds, releases water
  • Hydrolysis Reaction: Breaks chemical bonds, requires water

Carbohydrates

• Types and Examples:
  • Monosaccharides: Glucose, fructose, galactose
  • Disaccharides: Sucrose, maltose, lactose
  • Polysaccharides: Starch, cellulose, glycogen
• Glucose Structure:
  • Alpha and beta glucose are isomers
  • Formula: C6H12O6
  • Differences in hydrogen and hydroxyl group positions
• Disaccharides Formation: Glycosidic bonds through condensation
• Polysaccharides:
  • Starch and Cellulose: Found in plants, function as energy store and structural support
  • Glycogen: Found in animals, energy store
  • Structure-Function Links: Amylose (compact helix) and amylopectin (branched), cellulose (fibril structure)

Lipids

• Types:
  • Triglycerides: Glycerol and 3 fatty acids
  • Phospholipids: Glycerol, 2 fatty acids, and a phosphate group
• Properties:
  • Energy store, insoluble, hydrophobic
• Fatty Acids:
  • Saturated: No double bonds
  • Unsaturated: At least one double bond
• Phospholipid Properties:
  • Hydrophilic heads, hydrophobic tails
  • Forms bilayers in water

Proteins

• Structure:
  • Amino acids as monomers
  • Formed through condensation reactions, peptide bonds
• Levels of Structure:
  • Primary: Sequence of amino acids
  • Secondary: Alpha helix or beta pleated sheet, held by hydrogen bonds
  • Tertiary: 3D shape, held by ionic, hydrogen, and disulfide bonds
  • Quaternary: Multiple polypeptide chains

Enzymes

• Function: Catalyze reactions by lowering activation energy
• Specificity: Unique active site complementary to substrate
• Models:
  • Induced Fit Model: Active site molds around substrate
• Factors Affecting Activity:
  • Temperature, pH, substrate concentration, enzyme concentration, inhibitors

Biochemical Tests

• Starch: Iodine test
• Reducing Sugars: Benedict's test
• Non-Reducing Sugars: Acid hydrolysis followed by Benedict's
• Proteins: Biuret test
• Lipids: Ethanol emulsion test

Nucleic Acids: DNA and RNA

• DNA:
  • Stores genetic information
  • Structure: Double helix with complementary base pairing
• RNA:
  • Ribose sugar, uracil instead of thymine
  • Functions in protein synthesis

DNA Replication

• Process:
  • Semi-conservative
  • DNA helicase and DNA polymerase involved
• Historical Context: Watson, Crick, Franklin, Meselson, and Stahl

ATP

• Structure: Nucleotide derivative, energy carrier
• Function: Provides energy for cellular processes

Water

• Properties:
  • Metabolite, solvent, high heat capacity, large latent heat of vaporization, strong cohesion

Inorganic Ions

• Functions:
  • Hydrogen: pH balance, respiration
  • Iron: Hemoglobin
  • Sodium: Co-transport
  • Phosphate: DNA, RNA, ATP

This overview provides essential knowledge areas in the study of biological molecules for A-Level Biology, highlighting structures, functions, and biochemical significance.