AP Biology 1.3 Introduction to Biological Macromolecules. Study Notes - New Syllabus Effective 2025
AP Biology 1.3 Introduction to Biological Macromolecules. Study Notes- New syllabus
AP Biology 1.3 Introduction to Biological Macromolecules. Study Notes – AP Biology – per latest AP Biology Syllabus.
LEARNING OBJECTIVE
Describe the chemical reactions that build and break biological macromolecules.
Key Concepts:
- Monomers & Covalent Bonds
- Nucleic Acids
- Proteins
- Complex Carbohydrates
- Lipids
1.3 – Introduction to Macromolecules
🔨 Building Macromolecules: Dehydration Synthesis (Condensation Reaction)
What happens?
- Two monomers join to form a polymer
- Water is removed (H₂O is a byproduct)
Why important?
- This is how carbs, proteins, nucleic acids, and lipids are made
- Requires enzymes and energy (ATP) in cells
🧩 Example:
- Glucose + Glucose → Maltose + H₂O
- Amino acid + Amino acid → Dipeptide + H₂O
💧 Breaking Macromolecules: Hydrolysis
What happens?
- A polymer is broken into monomers
- Water is added to break the bond
Why important?
- Used in digestion and recycling molecules
- Releases energy and building blocks for the cell
🧪 Example:
- Maltose + H₂O → Glucose + Glucose
- Protein + H₂O → Amino acids
📝 Summary Table:
| Reaction | What it does | Water | Used in |
|---|---|---|---|
| Dehydration Synthesis | Builds polymers from monomers | Removed | Synthesis of macromolecules |
| Hydrolysis | Breaks polymers into monomers | Added | Digestion, breakdown |
💡 Quick Tip:
- Think of dehydration as “building by removing water” 🧱
- And hydrolysis as “breaking using water” 💧
1.3.A.1 – Hydrolysis Reaction (Breaking Macromolecules)
💧 What is Hydrolysis?
Hydrolysis = “Water + Split”
It’s a chemical reaction where water is used to break covalent bonds in polymers.
🧪 What Happens During Hydrolysis?
- A polymer is broken down into monomers
- Water (H₂O) is added to the bond:
- H⁺ (hydrogen ion) goes to one monomer
- OH⁻ (hydroxyl group) goes to the other
- This breaks the covalent bond between them
🔬 Why It Matters:
- Hydrolysis is how we digest large biomolecules (like proteins, carbs, etc.)
- It helps in cell recycling and releasing energy
- Happens naturally in cells using enzymes
💡 Example:
- Sucrose + H₂O → Glucose + Fructose
- Protein + H₂O → Amino acids
📌 Key Points to Remember:
- ✅ Water is added
- ✅ Bonds are broken
- ✅ Results in smaller molecules
- ✅ Essential in digestion and metabolism
1.3.A.2 – Dehydration Synthesis (Building Macromolecules)
🔗 What is Dehydration Synthesis?
Dehydration = “removal of water”
Synthesis = “to build”
→ It’s a chemical reaction where monomers are joined to form polymers by removing water.
⚙️ How It Works:
- Two monomers come together
- One loses a -H (hydrogen)
- The other loses an -OH (hydroxyl group)
- Together, they form H₂O (water) which is removed
- The leftover parts form a covalent bond = New polymer!
🧬 Why It Matters:
It’s how cells build large biomolecules like:
- Carbohydrates (from sugars)
- Proteins (from amino acids)
- Nucleic acids (from nucleotides)
This process is called polymerization.
🔄 Dehydration vs. Hydrolysis
| Dehydration Synthesis | Hydrolysis |
|---|---|
| Builds polymers | Breaks polymers |
| Removes water | Adds water |
| Needs enzymes | Needs enzymes |
🧠 Key Points to Remember:
- ✅ Water is removed
- ✅ Bonds are formed
- ✅ Builds larger molecules (polymers)
- ✅ Vital for growth and repair