AP Biology Complete Study Guide
1. Chemistry of Life
Water and Its Properties
• Polarity of Water: Oxygen is more electronegative than hydrogen, creating a partial negative
charge near oxygen and a partial positive charge near hydrogen.
• Hydrogen Bonding: Weak interactions between the slightly positive hydrogen atom and the
slightly negative oxygen of another water molecule.
• Properties of Water:
• Cohesion: Attraction between water molecules, contributing to surface tension (e.g.,
water droplets on a surface).
• Adhesion: Water’s ability to adhere to other materials (e.g., capillary action in
plants).
• High Heat Capacity: Water absorbs and retains heat, stabilizing temperatures in
organisms and environments.
• Solvent Properties: Water dissolves ionic and polar substances (e.g., NaCl dissolves
in water).
Macromolecules
1. Carbohydrates:
• Monosaccharides: Single sugar molecules like glucose and fructose.
• Disaccharides: Two sugars linked together (e.g., sucrose = glucose + fructose).
• Polysaccharides:
• Starch: Energy storage in plants.
• Glycogen: Energy storage in animals.
• Cellulose: Structural support in plant cell walls.
2. Lipids:
• Nonpolar and hydrophobic.
• Types:
• Fats/Triglycerides: Glycerol + 3 fatty acids.
, • Phospholipids: Glycerol + 2 fatty acids + phosphate group (forms cell
membranes).
• Steroids: Four fused rings (e.g., cholesterol, hormones).
3. Proteins:
• Functions: Enzymes, structure (collagen), transport (hemoglobin), signaling (insulin).
• Structure Levels:
• Primary: Amino acid sequence.
• Secondary: Alpha-helices and beta-sheets.
• Tertiary: 3D folding due to interactions (hydrophobic, hydrogen bonds, ionic
bonds).
• Quaternary: Multiple polypeptides (e.g., hemoglobin).
4. Nucleic Acids:
• DNA: Double-stranded, stores genetic info (A-T, G-C pairing).
• RNA: Single-stranded, involved in protein synthesis.
• Structure: Nucleotide = sugar + phosphate group + nitrogenous base.
Enzymes
• Catalysts that speed up reactions by lowering activation energy.
• Substrate: The molecule enzymes act upon.
• Active Site: Where substrate binds.
• Factors Affecting Enzymes:
• Temperature (denaturation at high temps).
• pH (optimal pH varies by enzyme).
• Substrate concentration (increases rate until saturation).
2. Cell Structure and Function
Cell Theory
• All living organisms are made of cells.
• Cells are the basic unit of life.
1. Chemistry of Life
Water and Its Properties
• Polarity of Water: Oxygen is more electronegative than hydrogen, creating a partial negative
charge near oxygen and a partial positive charge near hydrogen.
• Hydrogen Bonding: Weak interactions between the slightly positive hydrogen atom and the
slightly negative oxygen of another water molecule.
• Properties of Water:
• Cohesion: Attraction between water molecules, contributing to surface tension (e.g.,
water droplets on a surface).
• Adhesion: Water’s ability to adhere to other materials (e.g., capillary action in
plants).
• High Heat Capacity: Water absorbs and retains heat, stabilizing temperatures in
organisms and environments.
• Solvent Properties: Water dissolves ionic and polar substances (e.g., NaCl dissolves
in water).
Macromolecules
1. Carbohydrates:
• Monosaccharides: Single sugar molecules like glucose and fructose.
• Disaccharides: Two sugars linked together (e.g., sucrose = glucose + fructose).
• Polysaccharides:
• Starch: Energy storage in plants.
• Glycogen: Energy storage in animals.
• Cellulose: Structural support in plant cell walls.
2. Lipids:
• Nonpolar and hydrophobic.
• Types:
• Fats/Triglycerides: Glycerol + 3 fatty acids.
, • Phospholipids: Glycerol + 2 fatty acids + phosphate group (forms cell
membranes).
• Steroids: Four fused rings (e.g., cholesterol, hormones).
3. Proteins:
• Functions: Enzymes, structure (collagen), transport (hemoglobin), signaling (insulin).
• Structure Levels:
• Primary: Amino acid sequence.
• Secondary: Alpha-helices and beta-sheets.
• Tertiary: 3D folding due to interactions (hydrophobic, hydrogen bonds, ionic
bonds).
• Quaternary: Multiple polypeptides (e.g., hemoglobin).
4. Nucleic Acids:
• DNA: Double-stranded, stores genetic info (A-T, G-C pairing).
• RNA: Single-stranded, involved in protein synthesis.
• Structure: Nucleotide = sugar + phosphate group + nitrogenous base.
Enzymes
• Catalysts that speed up reactions by lowering activation energy.
• Substrate: The molecule enzymes act upon.
• Active Site: Where substrate binds.
• Factors Affecting Enzymes:
• Temperature (denaturation at high temps).
• pH (optimal pH varies by enzyme).
• Substrate concentration (increases rate until saturation).
2. Cell Structure and Function
Cell Theory
• All living organisms are made of cells.
• Cells are the basic unit of life.
