Question

Which of the following is true about different structures of protein?

• A. Secondary structure is the three-dimensional structure of protein
• B. Secondary structure is stabilized by disulfide bonds
• C. Primary, secondary and tertiary structures destroyed during denaturation
• D. Secondary and tertiary structure depends on the sequence of amino acids

Answer 1

The Correct Option is D

Proteins are complex macromolecules essential for various biological functions. They have different structural levels:

• Primary Structure: This is the linear sequence of amino acids in a protein and determines its unique characteristics.
• Secondary Structure: It refers to local structures like alpha helices and beta sheets, which are formed by hydrogen bonding between the backbone atoms in the polypeptide chain. It does not involve disulfide bonds; those are found in tertiary structures.
• Tertiary Structure: This is the overall three-dimensional structure of a single protein molecule. It is stabilized by various interactions including hydrogen bonds, ionic interactions, van der Waals forces, and disulfide bonds.
• Quaternary Structure: This exists in proteins with multiple polypeptide chains (subunits) and describes how these subunits assemble.

Denaturation primarily affects the secondary and tertiary structures, disrupting the non-covalent interactions without breaking peptide bonds that form the primary structure.

Considering the options:

• Secondary structure is the three-dimensional structure of protein: Incorrect. This describes the tertiary structure, not secondary.
• Secondary structure is stabilized by disulfide bonds: Incorrect. Secondary structures are stabilized mainly by hydrogen bonds.
• Primary, secondary and tertiary structures destroyed during denaturation: Incorrect. Denaturation affects secondary and tertiary structures but not the primary.
• Secondary and tertiary structure depends on the sequence of amino acids: Correct. The sequence determines the folding and interactions in secondary and tertiary structures.

Therefore, the correct statement is that secondary and tertiary structure depends on the sequence of amino acids.