Tag: biology

In the primary plant cell wall, the major carbohydrates are cellulose, hemicellulose and pectin. The cellulose microfibrils are linked via hemicellulosic tethers to form the cellulose-hemicellulose network, which is embedded in the pectin matrix. The most common hemicellulose in the primary cell wall is xyloglucan.

The bonds present between two carbohydrate molecules is glycosidic. A glycosidic bond is a type of covalent bond that joins a carbohydrate molecule to another group, which may or may not be another carbohydrate. A glycosidic bond is formed between the hemiacetal or hemiketal group of a saccharide and the hydroxyl group of some compound such as an alcohol. A substance containing a glycosidic bond is a glycoside.

Sweet tasting carbohydrates are called sugars, e.g., glucose and fructose. Starch is a storage polymer of glucose and is tasteless till it is broken down into monomer glucose molecule. Lactose is milk sugar. Proteins are polymers of amino acids which are tasteless except for some like aspartic acid. Saccharine is an artificial sweetener. Saccharin is more sweet than common table sugar or sucrose but has a bitter after taste.

Glucose is a monosaccharide carbohydrate. Glycogen is an important storage polysaccharide in animals like starch in plants. Glycogen and starch are homopolysaccharides made up of glucose units only. Glycogen is stored in liver and muscles in animals including humans. Starch is usually stored in endosperm and cotyledons of seeds. Waxes are a type of lipids.

Carbohydrates are the most abundant bimolecules found on the face of the earth. This is so because every year plants and alga through the process of photosynthesis converts more than 100 billion metric tones of $CO _2$ and $H _2O$ to cellulose and other products for use by the plants.

Proteins are the body building nutrients. Cell is the building block of our body. Most of the structures of the cells are formed with protein. Without protein no cell can be formed and be functional. So, proteins are called the body building nutrients.

Excess glucose is stored as starch or glycogen. Starch is storage polysaccharide in plants. Glycogen is storage polysaccharide in animals. In animals, including humans, glycogen is stored in two locations: muscles and liver.

Carbohydrates which are present in the cell membrane take part in cell recognition. Cell recognition is defined as an active process giving rise to a specific response.