Question

The structure of protein comprises of:
(A). Primary structure of protein is associated with amino acids
(B). Secondary structure of protein is associated to peptides
(C). Tertiary structure of protein is associated with polypeptide chains
(D). Quaternary structure of protein is associated with polypeptide chains
Choose the correct answer from the options given below:

• A. (A), (B) and (D) only.
• B. (A), (B) and (C) only.
• C. (A), (B), (C) and (D).
• D. (B), (C) and (D) only.

Hint:

Remember the hierarchy: Primary (sequence) \(\rightarrow\) Secondary (local folding) \(\rightarrow\) Tertiary (3D shape of one chain) \(\rightarrow\) Quaternary (arrangement of multiple chains). Each level builds upon the previous one.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Proteins have four levels of structural organization: primary, secondary, tertiary, and quaternary. Each level describes a different aspect of the protein's architecture.
Step 2: Detailed Explanation:
Let's evaluate each statement:
(A) Primary structure of protein is associated with amino acids: The primary structure is the unique linear sequence of amino acids linked together by peptide bonds to form a polypeptide chain. This statement is correct.
(B) Secondary structure of protein is associated to peptides: The secondary structure refers to the localized, regular folding of the polypeptide backbone, such as the \(\alpha\)-helix and \(\beta\)-sheet. These structures are stabilized by hydrogen bonds between the carbonyl oxygen and amide hydrogen of the peptide bonds in the backbone. Therefore, the secondary structure is indeed associated with the peptide components of the chain. This statement is correct.
(C) Tertiary structure of protein is associated with polypeptide chains: The tertiary structure is the overall three-dimensional shape of a single polypeptide chain. It results from interactions between the side chains (R-groups) of the amino acids. This statement accurately describes the tertiary structure as the structure of one complete polypeptide chain. This statement is correct.
(D) Quaternary structure of protein is associated with polypeptide chains: The quaternary structure exists only in proteins that consist of more than one polypeptide chain (subunit). It describes how these multiple polypeptide chains are arranged and interact with each other to form a functional protein complex. This statement is correct.
Step 3: Final Answer:
All four statements accurately describe the different levels of protein structure. Therefore, the correct option includes all of them.