Overview
This lecture introduces the chemical components of cells, focusing on the four main types of organic molecules: carbohydrates, lipids, proteins, and nucleic acids.
Chemical Components of Cells
- Cells are composed of chemical, structural, and functional components.
- Chemical components make up 70% water and 30% other molecules, mostly organic.
- Organic molecules always contain carbon and hydrogen.
Types of Organic Molecules
- Four main organic molecules: carbohydrates, lipids, proteins, and nucleic acids.
Carbohydrates
- Carbohydrates contain carbon, hydrogen, and oxygen; general formula: (CH2O)n.
- Classified as monosaccharides (one sugar unit), disaccharides (two units), and polysaccharides (many units).
- Monosaccharides include trioses (3 carbons, e.g., glyceraldehyde), pentoses (5 carbons, e.g., ribose), and hexoses (6 carbons, e.g., glucose).
- Disaccharides form from two monosaccharides; example: maltose (glucose + glucose).
- Polysaccharides are many glucose units; examples: starch (plants, energy storage), glycogen (animals, energy storage), and cellulose (plants, main cell wall component).
Lipids
- Lipids (fats and oils) are organic molecules insoluble in water.
- Three types: triglycerides (glycerol + 3 fatty acids, energy storage), phospholipids (phosphate + glycerol + fatty acids, cell membrane structure), and cholesterol (four carbon rings, membrane component).
Proteins
- Proteins are made from amino acids, each with a carboxyl group, amine group, and variable side chain (20 types).
- Amino acids link to form polypeptides, which fold into proteins.
- Protein functions include forming cell membranes and acting as enzymes.
Nucleic Acids
- Nucleic acids are long chains of nucleotides (each with phosphate, pentose sugar, and nitrogen base).
- Examples: DNA and RNA, serving as cell genetic material.
Key Terms & Definitions
- Organic Molecule — a compound containing carbon and hydrogen.
- Monosaccharide — simple sugar with one unit (e.g., glucose).
- Disaccharide — carbohydrate with two monosaccharide units (e.g., maltose).
- Polysaccharide — complex carbohydrate with many sugar units (e.g., starch).
- Triglyceride — lipid with glycerol and three fatty acids.
- Phospholipid — lipid with phosphate group, glycerol, and fatty acids.
- Amino Acid — building block of proteins, contains carboxyl, amine, and R group.
- Nucleotide — building block of nucleic acids, contains phosphate, pentose sugar, and nitrogen base.
Action Items / Next Steps
- Review the four types of organic molecules and their subtypes.
- Prepare for the next lesson on genetic material (DNA and RNA).