When a protein is in native form , is subjected to physical changes like change in temperature or chemical changes like change in pH the hydrogen bonds are disturbed. Due to this, globules unfold and helix get uncoiled and protein looses its biological activity. This is called denaturation of protein.
The denaturation causes the change in secondary and tertiary structures but primary structures remain intact. Examples of denaturation of protein are coagulation of egg white on boiling, curdling of milk, formation of cheese when an acid is added to milk.
Answer the following questions:
(a) Which structures remain intact during denaturation process?
(b) Cheese is a ________________ protein.
(c) What is denaturation process?
(d) Why a milk is curdled in coagulation process?
OR
Write the differences between fibrous proteins and globular proteins ?

(a) During denaturation of proteins secondary and tertiary structures are destroyed but primary structure remains intact.

(b) Cheese is a denatured protein. When producing (hard or semi-hard) cheese, the cheese yield can be increased by subjecting part of the cheese milk to a high-temperature heat treatment.

(c) denaturation, in biology, process modifying the molecular structure of a protein. Denaturation involves the breaking of many of the weak linkages, or bonds (e.g., hydrogen bonds), within a protein molecule that are responsible for the highly ordered structure of the protein in its natural (native) state.

(d) Because the micelle holds the casein protein in suspension, without it the micelles will clump together and the casein comes out of the solution. The result of this process of milk coagulation, or curdling, is a gelatinous material called curd.

OR

Fibrous proteins are structural in nature, which means they help maintain cell shape by providing a scaffolding or a framework. On the other hand, globular proteins are functional, which means they carry out a specific biological function in the body.