1. What is highly conserved among the homologous proteins over evolutionary time?
a) Protein sequence
b) DNA sequence
c) DNA structure
d) Protein structure
Explanation: 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.
2. 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)
Explanation: 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.
3. 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
Explanation: 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.
4. Which of the following terms is not related to X-ray crystallography?
a) Electron density maps
b) Diffraction pattern
c) Synchrotrons
d) Magnetic field
Explanation: 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.
5. Which of the following elements is not visible in the maps of X-ray crystallography?
a) Nitrogen
b) Carbon
c) Oxygen
d) Hydrogen
Explanation: 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.
6. Find the odd one out?
a) Hydrogen bond
b) Ionic bond
c) Hydrophobic interactions
d) Disulfide bond
Explanation: Hydrogen bond, Ionic bond, and hydrophobic interactions are types of non-covalent interactions. Disulfide bonds are a type of covalent interactions. Hence, the disulphide bond is the odd one out.
7. Which of the following options contain only non-covalent interactions?
a) Disulfide bond, Ionic bond
b) Ionic bond, peptide bond
c) Hydrogen bond, disulfide bond
d) Hydrogen bond, Ionic bond
Explanation: Hydrogen bond and Ionic bond are non-covalent interactions, whereas, disulfide bonds and peptide bonds are covalent interactions. Hence, among the options given the only option that contains only non-covalent interactions is hydrogen bond and Ionic bond.
8. Which of the following options contain only covalent interactions?
a) Disulfide bond, Ionic bond
b) Hydrogen bond, peptide bond
c) Hydrogen bond, Ionic bond
d) Disulfide bond, peptide bond
Explanation: Hydrogen bond and Ionic bond are non-covalent interactions. Disulfide bonds and peptide bonds are covalent interactions. Hence, among the options given the only option that contains only covalent interactions is disulfide bond, peptide bond.
9. Covalent interactions are generally weaker than non-covalent interactions.
a) true
b) false
Explanation: The above statement is false. Covalent interactions are always stronger than non-covalent interactions. Due to the sharing of electrons in covalent bonds, it is a strong bond. Examples of covalent interactions include disulfide bonds and peptide bonds.
10. Which among the following interactions is the weakest?
a) Disulfide bond
b) Peptide bond
c) Ionic bond
d) Hydrogen bond
Explanation: The bond energies are: disulfide bonds (251 kJ/mol), peptide bonds (80 kJ/mol), ionic bonds (42 kJ/mol), and hydrogen bonds (8-21 kJ/mol). Hence, among the given options hydrogen bond is the weakest bond.