Overview
This lecture covers the structure, types, and functions of lipids, emphasizing their hydrophobic nature and roles in biology.
Lipid Functions and Characteristics
- Lipids are used for long-term energy storage, insulation, cell membrane structure, and some hormone functions.
- All lipids are hydrophobic, meaning they repel water or have significant hydrophobic components.
Types of Lipids and Their Structures
- Lipids consist of two main building blocks: glycerol and fatty acids.
- Triglycerides are fats made from glycerol and three fatty acids.
- Saturated fats have fatty acids with no double bonds; unsaturated fats have fatty acids with one or more double bonds.
- Unsaturated fatty acids are less saturated with hydrogens due to the presence of double bonds.
Phospholipids and Cell Membranes
- Phospholipids have a polar, hydrophilic (water-attracting) head and a nonpolar, hydrophobic (water-repelling) tail.
- Phospholipids form the structure of cell membranes.
Steroids and Cholesterol
- Steroids are a type of lipid with a distinct structure.
- Cholesterol is a steroid that is important in cell membranes.
- Some hormones are also classified as steroids.
Key Terms & Definitions
- Lipid — Hydrophobic biological molecule used for energy, membranes, insulation, and some hormones.
- Fatty Acid — A hydrocarbon chain that can be saturated or unsaturated, forming part of a fat.
- Glycerol — A three-carbon alcohol that combines with fatty acids to form triglycerides.
- Triglyceride — A fat made of glycerol and three fatty acids.
- Saturated Fat — Fatty acids with no double bonds; fully saturated with hydrogen.
- Unsaturated Fat — Fatty acids with one or more double bonds; less saturated with hydrogen.
- Phospholipid — A lipid with a hydrophilic head and hydrophobic tail, key in cell membranes.
- Steroid — A lipid with a multi-ring structure, includes hormones and cholesterol.
- Cholesterol — A steroid important in cell membrane structure.
Action Items / Next Steps
- Review the structure and function of lipid types (triglycerides, phospholipids, steroids).
- Learn to identify saturated vs. unsaturated fatty acids in diagrams.