Organic Molecules Overview

Organic Molecules

• Organic compounds contain carbon; inorganic compounds do not.
• Four major classes of organic compounds essential to life: carbohydrates, proteins, lipids, nucleic acids.

Polymer Principles

• Most macromolecules are polymers made of monomers (subunits).
• Macromolecules represent an advanced level of biological organization, constructed from smaller building blocks.
• Polymerization occurs through dehydration or condensation reactions, linking monomers and removing water.
• Hydrolysis reactions break polymers into monomers by adding water, often catalyzed by digestive enzymes.
• An immense variety of polymers can arise from ~40 to 50 common monomers, showing diversity in life.

Carbohydrates

• Composed of sugars, which serve as fuel and structural components.
• Monosaccharides are simple sugars (e.g., glucose, fructose) with the formula CH₂O.
• Disaccharides consist of two monosaccharides joined via glycosidic linkages (e.g., maltose, sucrose, lactose).
• Polysaccharides are long chains of monosaccharides, used for energy storage (starch, glycogen) and structure (cellulose, chitin).

Starch and Glycogen

• Starch is a plant storage polysaccharide, made of helical glucose polymers; includes amylose (unbranched) and amylopectin (branched).
• Glycogen is an animal storage polysaccharide, highly branched, stored in muscle and liver tissues.

Cellulose and Chitin

• Cellulose is a linear polymer of β-glucose, forming plant cell walls and providing structural support.
• Chitin, composed of amino sugars, forms exoskeletons of arthropods and is found in fungal cell walls.

Lipids

• Lipids are hydrophobic and include fats, oils, and waxes.
• Triglycerides consist of three fatty acids attached to glycerol.
• Fatty acids are categorized as saturated or unsaturated (monounsaturated, polyunsaturated).
• Phospholipids have a phosphate group replacing one fatty acid and are fundamental to cell membranes.
• Steroids consist of four interconnected carbon rings and include hormones like cholesterol, testosterone, and estrogen.

Proteins

• Proteins are crucial for virtually all life functions and consist of one or more polypeptides folded into a specific 3D shape.
• Proteins are polymers of amino acids; there are 20 different amino acids categorized as hydrophobic, hydrophilic, or ionic.

Protein Function

• Functions include enzymatic activity, storage, hormonal signaling, movement, defense, transport, reception, and structure.

Protein Structure Levels

• Primary structure: Sequence of amino acids coded by DNA.
• Secondary structure: Stabilized by hydrogen bonds, forming alpha helices and beta-pleated sheets.
• Tertiary structure: The overall 3D shape stabilized by various weak interactions (hydrogen, ionic, hydrophobic) and strong covalent bonds (disulfide bridges).
• Quaternary structure: Formed from interactions between multiple polypeptides (e.g., collagen and hemoglobin).

Mutation and Denaturation

• A mutation alters the primary structure, as seen in sickle-cell disease, affecting hemoglobin shape and causing health issues.
• Proteins can denature due to factors like pH, salt concentration, and temperature, leading to loss of functional shape.

Explore the essential distinctions between organic and inorganic compounds. This quiz covers the four main classes of organic compounds critical to life: carbohydrates, proteins, lipids, and nucleic acids, as well as the principles of polymer chemistry. Test your knowledge on the formation and significance of macromolecules.