Chapter 21: Biochemistry
21.2: Carbohydrates
- Carbohydrates
- Organic molecules composed of carbon, hydrogen, and oxygen, typically in a 1:2:1 ratio. They are a primary source of energy for living organisms.
- Monosaccharides
- The simplest carbohydrates, often called simple sugars (e.g., glucose, fructose, galactose).
- Disaccharides
- Carbohydrates made of two monosaccharides linked by a glycosidic bond (e.g., sucrose, lactose, maltose).
- Polysaccharides
- Complex carbohydrates formed by the polymerization of many monosaccharides (e.g., starch, glycogen, cellulose).
- Glycosidic Bond
- A covalent bond that links monosaccharides in carbohydrates.
Functions of Carbohydrates
- Energy Source: Glucose is metabolized to provide energy for cellular processes.
- Energy Storage: Starch (in plants) and glycogen (in animals) store energy for later use.
- Structural Support: Cellulose provides rigidity in plant cell walls.
Types of Carbohydrates
- Monosaccharides: Simple sugars with one sugar unit, e.g., glucose.
- Disaccharides: Two sugar units bonded together, e.g., sucrose.
- Polysaccharides: Long chains of monosaccharides, e.g., cellulose, glycogen.
Importance of Carbohydrates
- Provide energy through cellular respiration.
- Support structural integrity in plants (cellulose).
- Serve as recognition molecules on cell surfaces (glycoproteins).
Questions for Students
- What is the general formula of carbohydrates, and why are they important?
- Define monosaccharides, disaccharides, and polysaccharides, and give examples of each.
- What is a glycosidic bond, and why is it significant in carbohydrate structure?
- Explain the role of carbohydrates in energy storage and structural support.
- Why are polysaccharides like cellulose and glycogen important for living organisms?