Carbohidratos: Aspectos generales y clasificación
Overview of Carbohydrates
General Characteristics
- Carbohydrates, also known as saccharides or glucids, are organic compounds made up of carbon, hydrogen, and oxygen. They are classified as polyhydroxy aldehydes or ketones due to their multiple hydroxyl groups in the structure.
- The primary function of carbohydrates is to serve as the main energy source for living organisms, providing approximately 4 kilocalories per gram.
Monosaccharides
- Monosaccharides are simple sugars that cannot be broken down into smaller molecules. Examples include glucose, galactose, ribose, and deoxyribose. Their general formula is Cn(H2O)n where n ≥ 3.
- The simplest monosaccharides contain at least three carbon atoms; they can be classified based on the position of their carbonyl group: aldoses (with an aldehyde group) and ketoses (with a ketone group).
Classification by Carbon Atoms
- Monosaccharides can also be categorized by the number of carbon atoms:
- Triose: 3 carbon atoms
- Tetrose: 4 carbon atoms
- Pentose: 5 carbon atoms
- Hexose: 6 carbon atoms
Oligosaccharides
- Oligosaccharides consist of short chains containing between two to ten monosaccharide units linked by glycosidic bonds. Disaccharides are a specific type formed from two monosaccharides.
- Disaccharides can be classified as:
- Homogeneous disaccharides: Composed of two identical monosaccharide units.
- Heterogeneous disaccharides: Composed of different monosaccharide units. Common examples include sucrose (glucose + fructose), lactose (glucose + galactose), and maltose (two glucose molecules).
Polysaccharides
- Polysaccharides are large molecules formed from more than ten monosaccharide units. Key examples include:
- Cellulose: A major component of plant cell walls.
- Chitin: Found in fungal cell walls and insect exoskeletons.
- Starch: A storage form of sugar in plants.
- Glycogen: A storage form of sugar in animals; both starch and glycogen consist of thousands of glucose molecules linked together.