Carbohydrates and its types

 Carbohydrates

Very few molecules out of a very large number may ionize. The presence of ions is molecules may ionize into hydrogen ions H and hidros ketone as functional groups attached to one of the carbon atoms. They also contain two yield such compounds on hydrolysis. Carbohydrates contain either aldehyde or Carbohydrates are polyhydroxy aldehydes or ketones or substances which or more hydroxyl groups. They are the most abundant biomolecules in nature. Carbohydrates are organic compounds that are mainly composed of carbon, hydrogen hydrogen and oxygen is present in the same ratio as in water that is 2:1. But now many means that they are hydrates of carbon in which carbohydrates are known that contain hydrogen and oxygen in different proportion.Examples of carbohydrates are glucose, sucrose, starch, cellulose etc. Carbohydrates, polysaccharides and oxygen. The name carbohydrates are classified into three groups, i.e. monosaccharides, oligosaccharides, Polysaccharides. 

Monosaccharides:

(Mono = one; Saccharum = sugar)

 monosacharide are simple sugars. They are not hydrolyzed (broken down by the

addition of water) into more simple units. They are easily soluble in water. They are

sweet in taste. They have empirical formula(CH20) containing the same ratio of

hydrogen and oxygen as in water, i.e. 2:1. They contain either aldehyde or keto group.

They have carbon backbone that may contain from three to seven carbon atoms. They have names which end in -ose. Those with three carbon atoms are celled trioses, with four atoms-tetroses, with five atoms-pentoses, and so on.

 Trioses the simplest monosaccharides with three carbon atoms. Glyceraldehyde is triose with aldehyde group. Ribose is a pentose.

It also contains aldehyde group. Ribulose is its ketonic form Glucose, fructose and galactose are hexoses. They have the same

empirical formula (CHO) but different structural formula. Such (ring form)

molecules with the same empirical

Isomerism and stereoisomerism in glucose

formula but different structures are

called isomers. Glucose is aldehyde while fructose is ketone. Therefore glucose,

fructose and galactose are isomers. They are inter-convertible. Ribose and glucose

when put in water form ring structures. Monosaccharides are white crystalline

powders. In stereoisomerism, the atoms making up the isomers are joined up in the

same order, but still manage to have a different spatial arrangement. Optical

sam isomerism is one form of stereoisomerism.

 Oligosaccharides

Oligosaccharides are hydrolyzed to form (break up) from two to ten simple

monosacharide units. The units or monomers are bonded together by glycosidic

bonds. The oligosaccharides that are hydrolyzed into two simple units are called

disaccharides, those hydrolyzed into three units are trisacchrides and so on.

Disaccharides are the most common oligosaccharides. Common disaccharides are

sucrose, lactose and maltose. Sucrose is present in sugarcane and is hydrolyzed into

Glucose and fractose. 

Polysaccharides

 Polysaccharides are polymers of monosaccharide units (monomers). They are

hydrolyzed into more than ten monomers of glucose units. They are tasteless and are

insoluble in water. Examples of polysaccharides are starch, glycogen, cellulose, chitin e.t.c 

Polysaccharides act as macromolecules (polymers) for the small carbohydrate

units. Green plants prepare glucose during photosynthesis, which is immediately

converted into starch. When plant needs glucose, starch is again converted into

glucose. Starch is stored in plant cells. Starch is a polymer made up of many glucose

units bonded together forming unbranched or branched chain. Glycogen is stored in

animal cells. It is also a polymer made up of glucose monomers forming extensively

branched chains.

Cellulose is another polysaccharide, formed of unbranched chain of glucose units. It is

the building material of green plant cell walls and is probably the most abundant

carbohydrate in nature. The bonds linking glucose units in a cellulose molecule are

digestive system. This is because the lack of its enzyme cellulase. Another example

oriented differently from starch and glycogen. Cellulose cannot be digested by human digestive system. This is because the lack of its enzyme cellulase. Another example of cellulose is cotton fibers. 

Chitin is a polysaccharide. It is found in the exoskeleton of arthropods such as crabs

and insects. It is also a polymer of glucose but an amino (-NH) group is attached to

each molecule. Like cellulose chitin is also not digestible.

Functions of Carbohydrates

Carbohydrates perform various important functions:

Source of energy

 Carbohydrates are used as source of energy. The C-H bonds in the carbohydrate molecules are broken down during respiration and the stored energy in these bonds is released which is made available to the cells for performing various Human

blood contains 100 mg of glucose per functions. Human blood contains 100mg of glucose per 100mg of glucose 100ml of blood. 

 

Storage Molecules

Carbohydrates are stored in the cells as reserve food. Grapes contain as much as 27%

glucose. Honey contains large amounts of glucose and fructose. Some of these polysaccharides such as starch and glycogen excess amount of food is stored for future use.

Structural Building Materials

Cellulose a complex carbohydrate is the major structural component of cell

walls of green plants. Similarly chitin another complex carbohydrate is the structural component of exoskeleton of arthropods.