Carbohydrates contain 3 elements these are:
- Hydrodgen and
Carbohydrates are found in three forms these are:
- Disaccharides which are double sugars and
General formula is:
(CH2O)n where n is a number between 3 and 9. They are classified according to the number of carbon atoms. The monosaccharides you will have to know fall into these categories:
C = 3 = triose
C = 4 = tetrose
C = 5 = pentose
C = 6 = hexose
Trioses: (e.g. glyceraldehydes), intermediates in respiration and photosynthesis.
Pentoses: (e.g. ribose, ribulose), used in the synthesis of nucleic acids (RNA and DNA), co-enzymes (NAD, NADP, FAD) and ATP.
Hexoses: (e.g. glucose, fructose), used as a source of energy in respiration and as building blocks for larger molecules.
All but one carbon atom have an alcohol (OH) group attached. The remaining carbon atom has an aldehyde or ketone group attached.
Due to the bond angles between the carbon atoms, it is possible for pentoses and hexoses to form stable ring structures. The carbon atoms are numbered 1 to 5 in pentoses and 1 to 6 in hexoses.
Depending on the orientation of the OH group on carbon 1, the monosaccharide can have either α or β configurations.
Disaccharides and glycosidic bonds
These are formed when two monosaccharides are condensed together. One monosaccharide loses an H atom from carbon atom number 1 and the other loses an OH group from carbon 4 to form the bond.
The reaction, which is called a condensation reaction, involves the loss of water (H2O) and the formation of an 1,4-glycosidic bond. Depending on the monosaccharides used, this can be an …