Overview
This lecture explains the chemical differences between saturated and unsaturated fats, their structures, and their physical properties.
Carbon Structure and Bonding
- Carbon has six electrons; two fill the first shell and four fill the second shell.
- Carbon is stable when it forms four covalent bonds with other atoms.
- Carbon can form single, double, or triple bonds, allowing complex molecular structures.
Categories of Organic Molecules
- Four major types: carbohydrates, proteins, nucleic acids, and lipids.
- Lipids are carbon-based molecules important for energy storage.
Lipid Structure
- Lipids consist of a glycerol "head" and up to three fatty acid hydrocarbon "tails."
- A triglyceride is a lipid with one glycerol and three fatty acids.
- Fatty acids are chains of carbon and hydrogen atoms called hydrocarbons.
Saturated Fatty Acids
- Saturated fatty acids have only single bonds between carbon atoms.
- Every carbon in the chain is fully saturated with hydrogen atoms.
- These molecules are dense, compact, and solid at room temperature (e.g., butter).
- Most saturated fats come from animal sources.
Unsaturated Fatty Acids
- Unsaturated fatty acids contain at least one double bond between carbon atoms.
- Double bonds reduce the number of hydrogen atoms and cause a bend (kink) in the chain.
- Unsaturated fats are liquid at room temperature (e.g., olive oil).
- They usually derive from plant and fish sources.
Types of Unsaturated Fatty Acids
- Monounsaturated: contain one double bond in the fatty acid chain.
- Polyunsaturated: contain multiple double bonds.
Key Terms & Definitions
- Carbon — An element with atomic number six, capable of forming four covalent bonds.
- Lipid — A type of organic molecule used for energy storage, made of glycerol and fatty acids.
- Fatty Acid — A hydrocarbon chain attached to glycerol in lipids.
- Saturated Fat — Fatty acid chains with all single bonds and maximum hydrogen atoms.
- Unsaturated Fat — Fatty acid chains with one or more double bonds and fewer hydrogen atoms.
- Monounsaturated Fat — Unsaturated fat with one double bond.
- Polyunsaturated Fat — Unsaturated fat with more than one double bond.
- Triglyceride — A lipid molecule with a glycerol and three fatty acid chains.
Action Items / Next Steps
- Review diagrams of saturated and unsaturated fatty acids for visual understanding.
- Memorize key differences between saturated and unsaturated fats for exams.