Introduction

1.Proteins are the polymers of ?-amino acids and they are connected to each other by peptide bond or peptide linkage forming a dipeptide. 2.For example, when carboxyl group of glycine combines with the amino group of alanine we get a dipeptide, glycylalanine. 3.A tripeptide contains three amino acids linked by two peptide linkages. 4.Similarly when four, five or six amino acids are linked, the respective products are known as tetrapeptide, pentapeptide or hexapeptide, respectively. 5. > 10 amino acids à polypeptides. 6.A polypeptide with more than hundred amino acid residues, having molecular mass higher than 10,000u is called a protein. 7.Polypeptides with fewer amino acids are likely to be called proteins if they have a well defined structure. Ex: Insulin which contains 51 amino acids. 8.When the polypeptide chains run parallel and are held together by hydrogen and disulphide bonds, then fiber– like structure is formed. 9.Such proteins are generally insoluble in water. 10.This structure results when the chains of polypeptides coil around to give a spherical shape. 11.These are usually soluble in water. 12.Insulin and albumin's are the common examples of globular proteins.

Pre-Requisites:

Elements, biomolecule

Activity:

Chief sources of proteins are milk, cheese, pulses, peanuts, fish, meat, etc

Real Life Question:

Which foods contain protein?

Key Words / FlashCards

Learning aids / Gadgets

Real life uses :

Proteins make up the enzymes within the body

Places to visit :

kitchen

Practical examples around us

What you learn in Theory:

1.Proteins are the polymers of ?-amino acids and they are connected to each other by peptide bond or peptide linkage forming a dipeptide. 2.For example, when carboxyl group of glycine combines with the amino group of alanine we get a dipeptide, glycylalanine. 3.A tripeptide contains three amino acids linked by two peptide linkages. 4.Similarly when four, five or six amino acids are linked, the respective products are known as tetrapeptide, pentapeptide or hexapeptide, respectively. 5. > 10 amino acids à polypeptides. 6.A polypeptide with more than hundred amino acid residues, having molecular mass higher than 10,000u is called a protein. 7.Polypeptides with fewer amino acids are likely to be called proteins if they have a well defined structure. Ex: Insulin which contains 51 amino acids. 8.When the polypeptide chains run parallel and are held together by hydrogen and disulphide bonds, then fiber– like structure is formed. 9.Such proteins are generally insoluble in water. 10.This structure results when the chains of polypeptides coil around to give a spherical shape. 11.These are usually soluble in water. 12.Insulin and albumin's are the common examples of globular proteins.

What you learn in Practice:

Amino acids make up protein