Rucete ✏ Campbell Biology In a Nutshell
Unit 1 THE CHEMISTRY OF LIFE — Concept 5.2 Carbohydrates Serve as Fuel and Building Material
Carbohydrates are fundamental to life, acting as both energy sources and structural components. They range from simple sugars to complex polysaccharides, each serving distinct roles in organisms.
1. Sugars: Monosaccharides and Disaccharides
Monosaccharides: Single sugar molecules like glucose (C₆H₁₂O₆) are the simplest carbohydrates. They serve as immediate energy sources and as building blocks for more complex sugars.
Disaccharides: Formed by two monosaccharides linked via a glycosidic bond. Common examples include sucrose (table sugar) and lactose (milk sugar).
2. Polysaccharides: Storage and Structural Roles
Storage Polysaccharides:
Starch: Plants store glucose in this form, which can be hydrolyzed for energy. It consists of amylose (unbranched) and amylopectin (branched).
Glycogen: Animals store glucose as glycogen, primarily in liver and muscle cells. It's highly branched, allowing rapid glucose release when needed.
Structural Polysaccharides:
Cellulose: A major component of plant cell walls, providing rigidity. It's a polymer of β-glucose, forming straight chains that bundle into strong fibers.
Chitin: Found in the exoskeletons of arthropods and fungal cell walls. Similar to cellulose but with nitrogen-containing side groups, enhancing strength.
3. Dietary Implications of Carbohydrates
Fiber: Indigestible carbohydrates like cellulose pass through the human digestive system, aiding in digestion and promoting gut health.
Lactose Intolerance: Some individuals lack lactase, the enzyme that breaks down lactose, leading to digestive discomfort when consuming dairy products.
In a Nutshell
Carbohydrates are versatile molecules serving as energy sources and structural materials.
They range from simple monosaccharides to complex polysaccharides with specialized functions.
Understanding their roles is essential for insights into both biological processes and nutritional science.