Question

Arrange the given steps in sequence in organization of protein structure:
A. Repeating structures recognise within 3-D polypeptide chains,
B. Sequence of amino acids in polypeptide chains,
C. Number of polypeptide chains come together to form active protein,
D. Overall 3-D polypeptide chain describe its bending, twisting et
C., E. Maintained by large number of weak bonds. Choose the correct answer from the options given below:

• A. A, B, E, D, C
• B. A, C, B, D, E
• C. B, A, D, E, C
• D. C, A, D, B, E

Hint:

Protein structure sequence is primary \(\rightarrow\) secondary \(\rightarrow\) tertiary \(\rightarrow\) quaternary.

Answer 1

The Correct Option is C

Concept:
Protein structure is organized into primary, secondary, tertiary and quaternary levels.

Step 1: Primary structure.
The first level of protein structure is the sequence of amino acids in a polypeptide chain. \[ B=\text{Primary structure} \]

Step 2: Secondary structure.
Repeating structures within the polypeptide chain, such as alpha helix and beta sheet, represent secondary structure. \[ A=\text{Secondary structure} \]

Step 3: Tertiary structure.
The overall three-dimensional bending, twisting and folding of one polypeptide chain represents tertiary structure. \[ D=\text{Tertiary structure} \]

Step 4: Stabilization of tertiary structure.
The three-dimensional structure is maintained by many weak bonds such as hydrogen bonds, ionic bonds, hydrophobic interactions and van der Waals forces. \[ E=\text{weak bond stabilization} \]

Step 5: Quaternary structure.
When several polypeptide chains come together to form an active protein, it represents quaternary structure. \[ C=\text{Quaternary structure} \] Therefore, the correct sequence is: \[ B,A,D,E,C \] \[ \therefore \text{Correct Answer is (C)} \]