GATE 2022 BT – Question 42
Which of the following are CORRECT about protein structure? P. Secondary structure is formed by a repeating pattern of interactions among the polypeptide backbone atoms Q. Tertiary structure is the three-dimensional arrangement of the polypeptide backbone atoms only R. Quaternary structure refers to an assembly of multiple polypeptide subunits
Practise this question in The GATE Grind →
Show answer and explanation
Correct answer: (B) P and R only
Explanation
Check each statement about protein structure.
- **P. Secondary structure is formed by a repeating pattern of interactions among the backbone atoms.** True. $\alpha$-helices and $\beta$-sheets are stabilised by hydrogen bonds between backbone C=O and N–H groups. ✓
- **Q. Tertiary structure is the 3D arrangement of the polypeptide backbone atoms only.** False. Tertiary structure is the overall 3D fold of **one chain including the side chains** (for example hydrophobic packing, salt bridges and disulfide bonds).
- **R. Quaternary structure is the assembly of multiple polypeptide subunits.** True (for example haemoglobin). ✓
Answer **P and R only** (B).