For being functional , a protein has to acquire at least

Options

A. Primary structure
B. Secondary structure
C. Tertiary structure
D. Quaternary structure.

Answer

To determine the level of protein structure required for functionality, we can analyze the different structural levels of proteins:

1. **Primary Structure**: This is the simplest level of protein structure, consisting solely of a sequence of amino acids linked by peptide bonds. While this sequence is essential for the formation of the protein, it does not confer any functional properties. Therefore, the primary structure alone is not sufficient for functionality.

2. **Secondary Structure**: This level involves the formation of local structures such as alpha helices and beta-pleated sheets, stabilized by hydrogen bonds. Although the secondary structure contributes to the overall shape of the protein, it still lacks the complexity needed for full functionality.

3. **Tertiary Structure**: This is the three-dimensional structure of a protein, formed by the folding of the polypeptide chain into a specific shape. The tertiary structure is stabilized by various interactions, including hydrogen bonds, disulfide bridges, ionic bonds, and hydrophobic interactions. This level of structure is crucial for the protein's functionality, as it determines the active sites and overall shape necessary for biological activity.

4. **Quaternary Structure**: This structure arises when multiple polypeptide chains (subunits) come together to form a functional protein complex. While not all proteins require a quaternary structure to be functional, those that do rely on this level of organization for their activity.

**Conclusion**: For a protein to be functional, it must at least acquire a tertiary structure. This level of organization provides the necessary three-dimensional shape and stability for the protein to perform its biological functions.