Match the level of protein structure with the appropriate description. 1) quaternary 2) tertiary 3) secondary 4) primary a) 3-dimensional shape of polypeptide chain b) hydrogen bonding within the peptide backbone c) assembly of subunits into functional protein d) linear sequence of amino acids
The Correct Answer and Explanation is:
Correct Matching:
- Quaternary — c) Assembly of subunits into functional protein
- Tertiary — a) 3-dimensional shape of polypeptide chain
- Secondary — b) Hydrogen bonding within the peptide backbone
- Primary — d) Linear sequence of amino acids
Explanation:
Proteins are complex molecules with structures organized into different levels. Each level contributes to the protein’s function, stability, and interaction with other molecules. The four levels of protein structure are primary, secondary, tertiary, and quaternary.
1) Primary Structure — d) Linear sequence of amino acids
The primary structure is the unique sequence of amino acids in a polypeptide chain. This sequence is determined by the genetic code and dictates how the protein will fold and function. It is held together by peptide bonds, which are covalent bonds between amino acids.
2) Secondary Structure — b) Hydrogen bonding within the peptide backbone
This level involves local folding patterns within a polypeptide chain, primarily forming alpha-helices and beta-pleated sheets. These patterns are stabilized by hydrogen bonds between the backbone atoms (not the side chains). The secondary structure gives the protein local rigidity and helps form its basic shape.
3) Tertiary Structure — a) 3-dimensional shape of polypeptide chain
The tertiary structure is the overall 3-dimensional shape of a single polypeptide. It results from interactions between the side chains (R-groups) of the amino acids. These interactions include hydrogen bonds, ionic bonds, hydrophobic interactions, and disulfide bridges. This level determines the protein’s functional form.
4) Quaternary Structure — c) Assembly of subunits into functional protein
Some proteins consist of more than one polypeptide chain, called subunits. The quaternary structure refers to how these subunits come together to form a functional protein. Hemoglobin is an example, made of four subunits that must work together to carry oxygen effectively.
Each level is essential to the protein’s stability, shape, and function.
