Simple sugar of monosaccharides

The two main types of sugars are monosaccharides and disaccharides. Monosaccharides consist of a single sugar molecule.

Monosaccharides may contain from three to nine carbon atoms although most of them contain five or six. A three carbon monosaccharide is called a triose; one containing four carbons is called a tetrose; five, a pentose; six, a hexose; seven, a heptose; eight an octose and nine a nonose.

α- D -glucose

*Pentoses (Arabinose, ribose, xylose) The pentose sugars, deoxyribose and ribose, are essential components of the genetic material DNA and RNA. E.g. glucose and fructose: (C6H12O6); arabinose and xylose: (C5H10O5).

Arabinose is found in gums and when several arabinose molecules are joined together, a pentosan formed.

*Hexoses
-Aldohexoses – galactose, glucose
-Ketohexose - fructose
 All hexoses have the same chemical formula C6H12O6, but slightly different structures. In nature, only fructose and glucose occur in free form. Galactose joined with glucose forms the disaccharide lactose.

Glucose is a hexose. Octoses and nanoses are quite rare. Glucose, the main source of energy for body cells, is found in most sweet fruits and in blood.
Simple sugar of monosaccharides

Monosaccharide - building blocks of carbohydrates

A carbohydrate is an organic compound made up of one or more sugar molecules.

The name of carbohydrate was applied originally to a group of compounds containing C, H and O that gave an analysis of (CH2O)n, i.e. compounds in which n carbon atoms appeared to be hydrated with n water molecules.

A carbohydrate consisting of a single sugar molecule is called a monosaccharide. A carbohydrate made of two molecules is a disaccharide.

Monosaccharide is the smaller compounds, containing three to nine carbon atoms. Monosaccharides are naturally present as simple sugars in fruits, milk and other foods.

It is a single sugar molecules that are made up of carbon, hydrogen, and oxygen atoms in the ration of 1:2:1.

Monosaccharides are used as building blocks to produce oligosaccharides, which contain from 2 to 10 monosaccharide residues and polysaccharides which contain more than 10 monosaccharide residues.

The most common monosaccharides in the human diet are: glucose, fructose and galactose. Although glucose, fructose and galactose have the same molecular formula (C6H12O6) each has a different arrangement of atoms.

Monosaccharide glucose is the most abundant simple carbohydrate unit in nature. Glucose gives food a mildly sweet flavor.

Monosaccharides are described either as aldoses or ketoses, depending on whether the molecule contains an aldehyde (aldoses) function or a ketone group.
Monosaccharide - building blocks of carbohydrates

Monosaccharides in food

The most common monosaccharides in the human diet are: glucose, fructose and galactose.

Glucose imparts a mildly sweet flavor to food. It seldom exists as a monosaccharides on food but is usually joined sugars to form disaccharides, starch or dietary fiber.

Fructose tastes the sweetest of all the sugars and occurs naturally in fruits and vegetables. Fructose also called fruit sugar or levulose.

The largest amount of fructose in American diets is added to foods when they are processed, such as the addition of high fructose corn syrup as a sweetener.

Galactose seldom found free in nature, galactose is part of lactose, the sugar found in milk.

The galactose formed combines with glucose to form lactose, which is secreted by mammals in the milk to sustain their young.

A derivative of galactose, galacturonic acid, is a component of pectin, which is very important in the ripening of fruits and the gelling of jams.

Monosaccharides in food

The meaning of carbohydrate

Carbohydrates is the most widely distributed, naturally occurring organic compounds on Earth.

Carbohydrates are major nutrients which supply the body with energy and of which billions of tons are produced every year though photosynthesis by plants and cyanobacteria.

The term carbohydrate literally means ‘carbon + water’ and partially describe its chemical makeup.

It was found in the nineteenth century that carbohydrates in general have formula Cn(H2O)n. They were therefore thought to be hydrates of carbon and hence were called carbohydrates.

Later it was found that carbohydrates in fact contain hydroxyl groups and carbonyl groups and are polyhydroxy aldehydes or ketones.

Carbohydrate also called saccharides an are usually divided onto three groups: monosaccharides, disaccharides and polysaccharides. Saccharides was from Greek word ‘sakcharon’ meaning sugar.

The term ‘monosaccharide’ refers to a carbohydrate derivative possessing a single carbon chain: ‘disaccharide’ and ‘trisaccharide’ refer to molecules containing two or three such monosaccharides units joined together by acetal or ketal linkages.

Carbohydrates posses a large number of functionalities, at least one carbonyl and several hydroxyl per monosaccharide and often carry kinds of functional groups.
The meaning of carbohydrate