Biomolecules easy notes class 12


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Biomolecules easy notes class 12

What is Biomolecules?

Major compounds of balanced food are carbohydrates, proteins, lipids, vitamins and minerals salts. These are basic constituents of the structure of a living body. So, these are also called biomolecules. Hormones and nucleic acids also included under biomolecules.

What is Carbohydrates?

Carbohydrates are optically active polyhydroxy aldehydes or polyhydroxy ketones or substances that will yield these types of compounds on hydrolysis.

Carbohydrates are classified as monosaccharides, oligosaccharides and are polysaccharides on the basis of their behaviour on hydrolysis.

Define Monosaccharides?

These cannot be hydrolysed further to give simpler unit of polyhydroxy aldehydes or ketones e.g. glucose, fructose.

Define Oligosaccharides.

These yield two to ten monosaccharides units on hydrolysis. They are further classified as di, tri saccherides, etc. depending upon the no. of monosaccharides they provide on hydrolysis.

Define Polysaccharides.

They yield a large number of monosaccharides units on hydrolysis e.g. starch, cellulose, glycogen.

What is Sugar?

These are colourless, crystalline and water soluble solid carbohydrates, whose taste in sweet. e.g. glucose, fructose, maltose, etc.

What is Molisch’s Test?

In the sample solution ( 2mL ), add 2mL of Molisch’s reagent (10% solution of \alpha -naphthol in etyl alcohol) and pouring H2SO4 along the wall of the test-tube, a ring of red or brown colour is formed in between the two substances, which becomes violet after sometime, which determine the presence of carbohydrates in the sample.

What is Glucose?

Glucose is the most important member of monosaccharides category. Glucose is formed by sucrose [C12H22O11] and starch [C6H10O5]n.

Define Fructose.

It is present in sweet fruits and honey along with glucose. Fructose is prepared by hydrolysis of dilute hydrochloric acid of inulin, at industrial level.

What is Cyclic structure of glucose

Biomolecules easy notes class 12
                              What is Cyclic structure of glucose

Glucose exists a cyclic hemiacetal structure in which —OH groups may add to —CHO groups and forms a six-membered ring in which —OH at C-5 is involved in ring formation.

Define Glycosidic linkage.

The two monosaccharides units are joined together by an oxide linkage formed by the loss of a water molecules. Such a type of link between two monosaccharides units through oxygen atom is known as glycosidic linkage.

What is Maltose?

Maltose is composed of two \alpha -D glucose unit in which C1 of (l) is linked to C4 of another glucose unit and also called reducing sugar (malt sugar).

What is Lactose?

Lactose it is composed of β-D galactose and β-D glucose. It is also a reducing sugar.

What is Starch?

It is also called amylase . It is a polymer of \alpha[/] -glucose.

Hydrolysis of starch in the presence of diastase gives maltose, which again hydrolysis and gives glucose. Water solution of the starch give blue colour on adding iodine.

What is Glycogen?

It works as stored glucose in the body. So, it is also called animal starch. It is a polymer of glucose and shows similarity with amylopectin in the structure.

What is Cellulose?

It is a non-reducing sugar. It is that carbohydrate which is not digested system of human. In quadrupedal animals, cellulose is digested by following bacterias present in their digestive system.

ο Fibrobactor succinogenes                        ο Ruminococcus flavefacines

Amino Acids

Molecules, which contain —NH2 and —COOH, both groups called amino acids. Proteins are polymers of amino acids, connected through peptide bonds (—CO—NH—).


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