20)a ) what are essential and non essential amino acids ? give one example of each type

B) what do you mean by denaturation of protein

 

Essential  amino acids

Those amino acids which cannot be synthesised by our body metabolism but are very essential in our diet are known as essential amino acids. They have to be supplied to our body by outside source through foods which contain them. Ex - arginine,histidine,lysine etc.

 Non essential amino acids

Non-Essential amino acids can be produced from other amino acids and substances.THey can be synthesised by our body .Ex - cystine, arginine, glysine etc.

 

Denaturation of proteins

Protein found in a biological system with a unique 3-D structure and biological activity is called a native protein. Many of the interactions that stabilize the 3-D conformation of the protein are relatively weak and are sensitive to various environmental factors including high temperature, low or high pH.

 

When a protein in its native form is subjected to a physical change such as heating or chemical change like treatment with mineral acids, hydrogen bonds are disturbed. Due to this, soluble forms of proteins such as globules unfold and helix get uncoiled. This causes globular protein to undergo coagulation or precipitation to give fibrous proteins which are insoluble in water and protein loses its biological activity. This is called denaturation. Upon denaturation or unfolding, 3-D structure of proteins is altered but their primary structure remains intact.

 

The most common example of denaturation of proteins is the coagulation of albumin present in the white of an egg. When egg is boiled hard, the soluble globular protein present in it is denatured resulting in the formation of insoluble fibrous proteins. 

 

 

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