The sugars

The importance of carbohydrates in biology

Carbohydrates are the most common source of energy in living organisms, and their digestion requires less water than protein or fat. The proteins and fats are structural components necessary for biological tissues and cells, and are also a source of energy for most organisms.

In particular, the monosaccharides are the greatest resource for metabolism. When there is no immediate need for often monosaccharides are converted into very best forms for the space, such as polysaccharides. In many animals, including humans, this form of storage is glycogen, located in the cells of the liver and muscles. The plants instead use the starch as a reserve. Other polysaccharides such as chitin, which contributes to the formation of the exoskeleton of arthropods, instead perform a structural function.

Polysaccharides represent an important class of biological polymers. Their function in living organisms is usually structural or deposit. The starch (a glucose polymer) is used as a storage polysaccharide in plants, and is located either in the form of amylose and in that branched amylopectin. In animals, the structurally similar polymer of glucose is the most densely branched glycogen, sometimes called “animal starch”. The properties of the glycogen allow it to be metabolized more quickly, which suits the active lives of the animals that move. The most widespread forms of glycogen liver glycogen and muscle glycogen. Liver glycogen is found in liver, it is the sugar reserves and energy in animals and lasts 24 hours. Muscle glycogen is the reserve of sugar used by muscle cells directly without going through the bloodstream. The liver glycogen, however, before reaching the cells and, in particular, the muscle tissue must be entered into the bloodstream.

The breakdown of sugars

The classification of the sugars depends on the number of molecules of which they are composed.
– Simple Sugars: they are those that are absorbed faster by the body, which turns them into energy immediately. Are for example simple sugars glucose, fructose (monosaccharide), sucrose, better known as the “common sugar kitchen” and lactose (disaccharides). Cause – if taken alone – an immediate rise in blood glucose in the blood and a sharp drop in this next, going to lead to a feeling of hunger. Simple sugars are contained mainly in fruits, in milk, candies and sweet baked goods (biscuits, pastries, etc.) and spreads (honey, various creams, jams, etc.).
– Complex Sugars: are those in slower digestion, being assimilated gradually, act prolonging satiety. Are for example complex sugars (polysaccharides) the starch contained in bread, pasta, rice, legumes, potatoes, chestnuts, and bananas, and glycogen content in muscles and liver

Functions and energy needs

The sugars (also called carbohydrates or carbohydrates) provide about 4 calories per gram and are present both in the cells that in the blood.
The quantity of sugars (in particular glucose) in the blood, called blood glucose, should be kept constant; a value of very high blood sugar (hyperglycemia) is one of the main symptoms of diabetes.

– Energy Function: are the source of energy easier and more immediate use, which the body draws to breathe, move, grow.
– Reserve Function: complex sugars are often stored as energy reserve (in the muscles, in the case of glycogen) or transformed into fat, so going to be the fat tissue.

The daily requirement of sugar of an adult should be around 50-60% of the caloric share, of which only 10-15% should come from simple sugars. For example, within a 2100 calorie diet, you should assimilate 56-84 grams of sugar.

The composition of the sugars

From a chemical point of view, there are different classifications of saccharides. Depending on the number of repeating units that comprise them, they can be divided into:

monosaccharides: formed by only one repeating unit; among these they include glucose, galactose and fructose;

oligosaccharides: consisting of a few repeating units

disaccharides: made of two repeating units;

trisaccharides: consist of three repeating units;

polysaccharides: formats of many repeating units

The repeating units of oligosaccharides and polysaccharides are linked by glycosidic bonds.

I also carbohydrates are divided into:

Simple carbohydrates: monosaccharides and oligosaccharides.

From the chemical point of view, the carbohydrates are aldehydes or ketones to which various hydroxyl groups have been added, usually one on each carbon atom that is not part of the aldehyde or ketone functional group. Carbohydrates with a higher molecular weight can therefore be considered poliidrossialdeidi or poliidrossichetoni.

Most of the carbohydrates may be described by the formula Cm (H2O) n, where n is a number greater than or equal to three and m, may be different from n. Some exceptions are the uronic acids and the deoxy sugar such as fucose.