What is meant by tertiary structure of proteins?
The tertiary structure of proteins refers to the overall three-dimensional arrangement of a single polypeptide chain. In this structure, the long protein chain is folded upon itself like a hollow woolen ball.
This folding gives us a 3-dimensional view of a protein. The tertiary structure is formed when the protein chain, which already has secondary structures like helices, further folds upon itself.
The tertiary structure is absolutely necessary for the many biological activities of proteins. Without this specific three-dimensional shape, proteins cannot perform their biological functions properly.
Explanation
The textbook explains that after the secondary structure (where protein threads are folded into helices), the long protein chain further folds upon itself like a hollow woolen ball. This gives rise to the tertiary structure, which provides a 3-dimensional view of the protein. The context emphasizes that this structure is absolutely necessary for many biological activities of proteins.