Overview
This lecture introduces macromolecules, focusing on the processes of building and breaking down polymers—dehydration synthesis and hydrolysis—vital concepts for understanding biological molecules in living organisms.
What Are Macromolecules?
- Macromolecules are large biological molecules made primarily of carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur.
- The main biological macromolecules are carbohydrates, proteins, lipids, and nucleic acids.
- Macromolecules consist of smaller subunits called monomers linked together to form polymers.
Monomers vs. Polymers
- A monomer is a small molecule that can bind to others to form a polymer.
- A polymer is a large molecule made by joining many monomers via covalent bonds.
- Dimer refers to a molecule made from two monomers.
Importance in Living Things
- Living things require intake of carbon-based molecules (food) from their environment.
- Food is broken down and rearranged to build the molecules needed by cells.
- The breakdown and rebuilding of these molecules is part of metabolism.
Hydrolysis
- Hydrolysis is the process of breaking down polymers into monomers.
- In hydrolysis, water is added to break covalent bonds between monomers.
- One monomer receives a hydrogen ion (H), and the other receives a hydroxyl group (OH) from the water molecule.
- This reaction requires the help of enzymes.
Dehydration Synthesis
- Dehydration synthesis is the process of joining monomers to form polymers.
- An H from one monomer and an OH from another are removed to form a water molecule, allowing a new covalent bond between the monomers.
- Multiple dehydration synthesis reactions create long polymers (polymerization).
Summary & Key Points
- Food polymers must be broken down to monomers via hydrolysis before being rebuilt into new polymers by dehydration synthesis.
- Hydrolysis and dehydration synthesis are opposite reactions crucial for metabolism.
Key Terms & Definitions
- Macromolecule — a large molecule made of smaller subunits.
- Polymer — a large molecule made of repeating monomers.
- Monomer — a small subunit that can join others to form a polymer.
- Hydrolysis — reaction that breaks polymers into monomers using water.
- Dehydration Synthesis — reaction that joins monomers to make polymers by removing water.
- Polymerization — process of linking many monomers to form a polymer.
- Enzyme — a protein that speeds up chemical reactions (covered more in Unit 3).
Action Items / Next Steps
- Review definitions of monomer, polymer, hydrolysis, and dehydration synthesis.
- Prepare for the next lesson on carbohydrates.