Summary
Highlights
Carbohydrates are prevalent in daily life, found in items like bread, rice, and even cellulose in clothes. Primarily from plants, they provide energy, form supporting structures like plant cell walls, are used to make other organic compounds (amino acids, fats, DNA), and serve as lubricants. They are organic compounds of carbon, hydrogen, and oxygen, with hydrogen and oxygen in a 2:1 ratio.
There are three main types of carbohydrates: monosaccharides, disaccharides, and polysaccharides. Monosaccharides, or simple sugars, have a simple chemical composition. Examples include glucose, fructose, and galactose. Glucose, with the chemical formula C6H12O6, is one of the simplest forms, fitting the generalized carbohydrate formula CnH2mOm where n and m equal 6.
Disaccharides are complex sugars formed from two simple sugar molecules condensed together. Common examples include maltose, lactose, and sucrose, all typically having 12 carbon atoms with the general formula C12H22O11. Differences arise from atomic arrangement. Sucrose (cane sugar) is a combination of glucose and fructose; lactose (milk sugar) is glucose and galactose; and maltose (malt sugar) is two glucose molecules.
The formation of a disaccharide from two simple sugars is a condensation reaction, where a water molecule is removed. Conversely, breaking down a disaccharide into monosaccharides occurs through hydrolysis, a reaction that adds a water molecule, often facilitated by an enzyme.
Polysaccharides are the most chemically complex carbohydrates. Examples include starch and cellulose. Additionally, some substances like chitin in arthropod skeletons are slightly modified carbohydrates.