Carbohydrate A polyhydroxyl ketone

Carbohydrate a polyhydroxyl ketone or polyhydroxyl aldehyde or a polymer composed of these. (22.6) Carboxyhemoglobin a stable complex of hemoglobin and carbon monoxide that prevents normal oxygen uptake in the blood. (20.8)... 

Carbohydrate a polyhydroxyl ketone or polyhydroxyl aldehyde or a polymer composed of these. 

The word carbohydrate was used originally to describe glucose, which has the formula CgH Og and was once thought to be a "hydrate of carbon," Cft( H20)6. Although this view was soon abandoned, the word persisted and is now used to refer to a large class of polyhydroxylated aldehydes and ketones. Glucose, for example, is a six-carbon aldehyde with five hydroxyl groups. 

Carbohydrates are a class of naturally occurring polyhydroxylated aldehydes and ketones, which are commonly called sugars. Many, but not all, sugars have the empirical formula C,(H,0)v. 

Most of the carbohydrates discussed in this chapter are polyhydroxylated aldehydes or ketones, although there are other polyhydroxylated derivatives. Carbohydrates can be classified in two fruidamental ways The first is based on the type of functional group that accompanies the hydroxyl units and the second on the molecular size of the carbohydrate. If the fundamental unit of a carbohydrate is 1, carbohydrates are classified by the nature of the functional groups and X. In structure 1, several repeating CHOH units are defined by the integer n, where n = 3, n = 5, n = 6, etc. When n = 3, for example, 1 is X -CHOH-CHOH-CHOH-X. Most carbohydrates are defined by making X and/or X = CH2OH, CHO, COR (a ketone), or COOH. 

The word carbohydrate derives historically from the fact that glucose, the first simple carbohydrate to he obtained in pure form, has the molecular formula CeHi206 and was originally thought to be a hydrate of carbon, C6(H20)6- This view was soon abandoned, but the name survived. Today, the term carbohydrate is used to refer loosely to the broad class of polyhydroxylated aldehydes and ketones commonly called sugars. Glucose, also known as dextrose in medical work, is the most familiar example. 

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