What You Will Learn!
- The students will get a wide picture of Biomolecules.
- The students will learn about Carbohydrates and vitamins.
- The students will have a deep knowledge about the Classification of carbohydrates and proteins..
- The students will know about the importance of DNA and RNA.
Description
The group of compounds known as carbohydrates received their general
name because of early observations that they often have the formula
Cx(H2O)y - that is, they appear to be hydrates of carbon.
The above definition could not survive long due to the following reasons:
(i) A number of compounds such as rhamnose, (C6H12O5) and
2-deoxyribose (C5H10O4) are known which are carbohydrates by their
chemical behaviour but cannot be represented as hydrates of carbon.
(ii)There are other substances like formaldehyde (HCHO, CH2O) and
acetic acid [CH3COOH, C2 (H2O)2] which do not behave like
carbohydrates but can be represented by the general formula, Cx(H2O)y.
Carbohydrates are defined as polyhydroxy aldehydes or polyhydroxy
ketones or substances which give these on hydrolysis and contain at least
one chiral carbon atom. It may be noted here that aldehydic and ketonic
groups in carbohydrates are not present as such but usually exist in
combination with one of the hydroxyl group of the molecule in the form of
hemiacetals and hemiketals respectively.
Classification
The carbohydrates are divided into three major classes depending upon
whether or not they undergo hydrolysis, and if they do, on the number of
products formed.
(i)Monosaccharides: The monosaccharides are polyhydroxy aldehydes or
polyhydroxy ketones which cannot be decomposed by hydrolysis to give
simpler carbohydrates. Examples are glucose and fructose, both of which
have molecular formula, C6H12O6.
(b) Trisaccharides, which yield three monosaccharide molecules on
hydrolysis. Example is raffinose, which has molecular formula,
C18H32O16.
(c)Tetrasaccharides, etc.
(iii)Polysaccharides: The polysaccahrides are carbohydrates of high
molecular weight which yield many monosaccharide molecules on
hydrolysis. Examples are starch and cellulose, both of which have
molecular formula, (C6H10O5)n.
Who Should Attend!
- For the Beginners and students of twelfth standard.
