250+ TOP MCQs on Tertiary Structure of Protein and Answers

Protein Engineering Multiple Choice Questions on “Tertiary Structure of Protein”.

1. Which among the following structure of a protein describes the folding of its secondary structural elements and specifies the position of every atom in a protein, including those of side chains?
A. Primary structure
B. Secondary structure
C. Quaternary structure
D. Tertiary structure
Answer: D
Clarification: Tertiary structure of a protein describes the folding of its secondary structural elements and specifies the position of every atom in a protein, including those of side chains. Moreover, the tertiary structure of a protein consists of secondary structural elements that join to form motifs and domains.

2. In the tertiary structure of protein, the non-polar residues tend to occur in the protein interior and polar residues on the exterior.
A. False
B. True
Answer: B
Clarification: Generally, a globular protein contains both polar and non-polar residues. The polar residues are present mostly on the outer surface of a protein to interact with the hydrophilic environment. The non-polar residues reside in the interior of the protein. Hence, the above statement is true.

3. Which among the following residues is most likely to be present on the surface of a protein?
A. Val
B. Leu
C. Ile
D. Arg
Answer: D
Clarification: Arg is most likely to be present on the surface of a protein because it is a polar residue. Generally, polar residues reside on the surface of a protein. Val, leu, and Ile are non-polar residues, hence, they are not likely to be present on the surface of a protein.

4. Which among the following residues is most likely to be present in the interior of a protein?
A. Arg
B. His
C. Asp
D. Val
Answer: D
Clarification: Val is most likely to be present in the interior of a protein because it is a non-polar residue. Generally, non-polar residues reside in the interior of the protein. Arg, His, and Asp are polar residues, hence, they are not likely to be present in the interior of a protein.

5. Find the odd one out.
A. Phe
B. Met
C. Leu
D. Glu
Answer: D
Clarification: Glu is the odd one out. Glu is a charged, polar amino acid and is, therefore, most likely to be present on the surface of a protein. Phe, Met, and leu are non-polar, thus, likely to be present in the interior of the protein.

6. Which of the following options contain only those amino acids that are likely to be present on the surface of a protein?
A. Arg, Met, Lys
B. Met, Leu, Asp
C. Lys, Leu, Val
D. Arg, Asp, Lys
Answer: D
Clarification: The option containing Arg, Asp, and Lys is the correct option. Due to the polar nature of Asp, Arg, and Lys, they are most likely to be present on the surface of a protein. Leu, Val, and Met are non-polar residues.

7. Which of the following options contain only those amino acids that are likely to be present in the interior of a protein?
A. Arg, Val, Met
B. Asp, Met, Phe
C. Lys, Phe, Val
D. Val, Met, Phe
Answer: D
Clarification: The option containing Val, Met, and Phe is the correct option. Val, Met, and Phe are all non-polar residues, hence, likely to be present in the interior of the protein. Arg, Asp, and Lys are polar residues.

8. Serine is always present on the surface of protein.
A. True
B. False
Answer: B
Clarification: Serine is usually present on the surface of a protein but it can also be found in the interior of the molecule. When present in the interior it is always hydrogen-bonded to neutralize the polarity. Hence, the above statement is false.

9. Which of the following is a structural database?
A. CATH
B. SCOP
C. VAST
D. PDB
Answer: D
Clarification: PDB is a structural database. PDB stands for Protein Data Bank. It is the repository of structural information. CATH, SCOP, and VAST are not structural databases, on the contrary, they are structural classification algorithms. PDB archive is the single worldwide repository of information about the 3D structures of large biological molecules, including proteins and nucleic acids.

10. Which among the following is not a structural database?
A. PDB
B. MMDB
C. Nucleic acid database
D. CATH
Answer: D
Clarification: CATH is not a structural database, but it is a structural classification algorithm. CATH provides hierarchial classification of protein domains based on their folding patterns. PDB, MMDB (Molecular Modelling Database), and Nucleic acid database are structural databases.

11. What is highly conserved among the homologous proteins over evolutionary time?
A. Protein sequence
B. DNA sequence
C. DNA structure
D. Protein structure
Answer: D
Clarification: It is the protein’s structure that is highly conserved among the homologous proteins over the evolutionary time. It is the protein 3D structure that is responsible for its biological activity and not its sequence.

12. Which among the following is not a technique to determine the structure of a protein?
A. X-ray crystallography
B. NMR spectroscopy
C. cryo-electron microscopy
D. Mass spectrometry (MS-MS)
Answer: D
Clarification: Among the given options Mass spectrometry is not a technique to determine the structure of a protein. It is a technique used to determine the protein sequence. X-ray crystallography, NMR spectroscopy, and cryo-electron microscopy are all techniques to determine the structure of a protein.

13. The term “electron density maps” is related to which of the following technique?
A. Optical microscopy
B. NMR spectroscopy
C. cryo-electron microscopy
D. X-ray crystallography
Answer: D
Clarification: X-ray crystallography is a technique where in electron density maps are obtained. Thus, the term “electron density maps” is related to X-ray crystallography. Other techniques mentioned do not involve electron density maps.

14. Which of the following terms is not related to X-ray crystallography?
A. Electron density maps
B. Diffraction pattern
C. Synchrotrons
D. Magnetic field
Answer: D
Clarification: The magnetic field is not related to X-ray crystallography. It is related to NMR Spectroscopy. Electron density maps, diffraction patterns, and synchrotrons are related to X-ray crystallography.

15. Which of the following elements is not visible in the maps of X-ray crystallography?
A. Nitrogen
B. Carbon
C. Oxygen
D. Hydrogen
Answer: D
Clarification: Hydrogen atom is not visible in the electron density maps of X-ray crystallography. The reason behind this is the low electron density of the hydrogen atom. Hydrogen contains a minimum of one electron.