Answer the question on the basis of the passage given below:

Proteins are the polymers of about twenty different \(\alpha \)-amino acids which are linked by peptide bonds. Proteins perform various structural and dynamic functions in the organisms. Proteins which contains only \(\alpha \)- amino acids are called simple proteins. The secondary or tertiary structures of proteins gets disturbed on change of pH or temperature and they are not able to perform their functions. This is called denaturation of proteins. Enzymes are biocatalysts which speed up the reactions in bio systems. Vitamins are accessory food factors required in the diet. They are classified as fat soluble (A, D, E and K) and water soluble (B and C). Deficiency of vitamins leads to many diseases. Nucleic acids are the polymers of nucleotides which in turn consists of a base, a pentose sugar and phosphate moiety. Nucleic acids are responsible for the transfer of characters from parents to offspring’s. There are two types of nucleic acids: DNA and RNA. DNA contains a five carbon sugar molecule called 2-deoxyribose whereas RNA contains ribose.

During denaturation of protein

\(1^o\) structure remains unaltered

The correct answer is: (4) \(1^o\) structure remains unaltered

Denaturation is the process by which the three-dimensional structure of a protein is disrupted. This can be caused by a variety of factors, such as heat, pH changes, and exposure to certain chemicals.

Denaturation destroys the secondary, tertiary, and quaternary structures of a protein, but leaves the primary structure intact. The primary structure is the sequence of amino acids in the protein.

The other options are incorrect:

(1) is incorrect because the biological activity of a protein is dependent on its three-dimensional structure. When the protein is denatured, its biological activity is lost.

(2) is incorrect because the secondary structure of a protein is destroyed during denaturation. The secondary structure is the regular folding of the protein chain into alpha-helices and beta-pleated sheets.

(3) is incorrect because the tertiary structure of a protein is destroyed during denaturation. The tertiary structure is the three-dimensional arrangement of the secondary structure elements.

Here is an example of denaturation:

When an egg is cooked, the heat denatures the proteins in the egg white. This causes the egg white to coagulate and turn white.

Denaturation can also be used to purify proteins. For example, enzymes can be denatured by heat or exposure to certain chemicals. This denatures any unwanted proteins in the mixture, making it easier to purify the desired enzyme.