This set of Pharmaceutical Biotechnology Interview Questions and Answers focuses on “Peptide and Protein Structure Stability Profile – 1”.
1. Interactions between atoms within the protein chain are one of the main forces that stabilize covalent structures in Proteins.
a) True
b) False
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Explanation: The main forces that stabilize the covalent structures of the protein are an interaction between atoms within the protein chain and interaction between the protein and the solvent. Interactions which helps in stabilizing the protein structure are disulfide bonds, hydrogen bonds, salt bridges, hydrophobic interactions, hydrophilic interactions, and ionic interaction.
2. One of the Main Forces that stabilize covalent structures in proteins is the interaction between the protein and the ____________
a) Other protein
b) Cells around
c) Solvent
d) Cell debris around
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Explanation: The interaction between the protein and the solvent around makes a protein structure stable. Also, the interaction between the protein atoms within the protein structure makes the structure stable. Most of the common interaction found in a protein structure are disulfide bonds, hydrogen bonds, salt bridges, hydrophobic interactions, hydrophilic interactions, and ionic interaction.
3. Salt Bridges is one of the Interactions stabilizing protein structure.
a) True
b) False
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Explanation: Salt bridges are one of the several types of interaction which helps in the stability of protein structure. Salt bridges are ionic interactions between ionized R groups of the amino acids and the water on the surface of the tertiary structure.
4. What is the disulfide bond?
a) The ionic bond between S-S
b) Vander Waals interaction between two S atoms
c) The covalent bond between sulfur atoms on two cysteine amino acids
d) The covalent bond between any two sulfur atoms
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Explanation: Covalent bond between sulfur atoms on two cysteine amino acids. Two cysteine amino acids atoms in close proximity will come together and then form a covalent bond in between with the release of a water molecule. The bond formed is covalent bond rather than ionic, Vander Waals or non-ionic.
5. Which bond is weak and allow to be broken and reformed easily
a) Disulfide bond
b) H bond
c) Hydrophobic interaction
d) Electrostatic bond
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Explanation: H bonds weak bonds allowing to be broken and reformed easily. Allows structural change in the protein structure. Hydrogen bonds produce ‘functional’ molecules.
6. H bond doesn’t allow structural change.
a) True
b) False
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Explanation: Hydrogen bond is a very weak bond which is formed with the interaction between hydrogen and oxygen atoms. This although weak is a very important force for the structure of a protein. This bond can easily break and newly form by changing the structure of the protein.
7. Salt bridges are which kind of bonds?
a) Disulfide bond
b) H bond
c) Hydrophobic interaction
d) Electrostatic bond
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Explanation: Salt bridges are electrostatic bonds between oppositely charged groups. The ions on the R group of amino acids form salt bridges through electrostatic bonds. The strength of the bond is usually 4-7 kcal/mol.
8. What is the strength of salt bridges?
a) 10-15 kcal/mol
b) 20-25 kcal/mol
c) 17-20 kcal/mol
d) 4-7 kcal/mol
View Answer
Explanation: The energy needed to break a salt bridge is around 4-7 kcal/mol. Salt bridges are electrostatic bonds between oppositely charged groups. The ions on the R group of amino acids form salt bridges through electrostatic bonds.
9. Hydrophobic interactions are attractive interactions, resulting from the inability of water to form hydrogen bonds with certain side chains.
a) True
b) False
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Explanation: Hydrophobic attractions are an attraction between the nonpolar alkyl groups and aromatic groups form a non-polar center that is repelled by water. Hydrophilic attractions are an attraction between polar or ionized R groups and water on the surface of the tertiary structure.
10. What is the name of attractions between polar or ionized R groups and water on the surface of the tertiary structure?
a) Disulfide bond
b) H bond
c) Hydrophilic interaction
d) Electrostatic bond
View Answer
Explanation: Hydrophilic attractions are attractions between polar or ionized R groups and the water on the surface of the tertiary structure. Hydro means water and phallic means loving. These bonds are water-loving bonds and therefore always takes into account the surrounding water.
11. Which of the bonds are between the polar side groups of amino acids?
a) Disulfide bond
b) Hydrogen bond
c) Hydrophobic interaction
d) Electrostatic bond
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Explanation: This bonds in protein structure occurs between the COO group on one side of amino acid and polar side groups of other amino acids. They are weak forces. Hydrogen bonds are responsible for the structural changes in the protein.
12. What is the name of the links between sulfur atoms of two cysteine amino acids?
a) Disulfide bond
b) H bond
c) Hydrophobic interaction
d) Electrostatic bond
View Answer
Explanation: Disulphide bonds are strong covalent links between the sulfur atoms of 2 cysteine molecules. When two sulfur atoms from 2 different cysteine molecules form bind they release a water molecule. It is an oxidative reaction.
13. What is the approximate strength of the interaction between atoms in a covalent bond?
a) 500 kJ/mol
b) 150 kJ/mol
c) 100 kJ/mol
d) 250 kJ/mol
View Answer
Explanation: Covalent bond is a bond formed by the sharing of electrons. The bonds in all the polyatomic ions and diatomics are all covalent bonds. The energy needed to break a covalent bond is 250 kJ/mol. It is the strongest bond of electrostatic, van der Waals force, and hydrogen bond.
14. Which of the following of a protein molecule determines the strength of van der Waals force?
a) The molecular weight of the protein
b) PI of the protein
c) Number of amino acids present
d) The surface area of the molecule
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Explanation: The surface area of a molecule determines the strength of the van der Waals interactions between molecules. The larger the surface area, the larger the attractive force between two molecules, and the stronger the intermolecular forces. They are weak interactions caused by momentary changes in electron density in a molecule.
15. In secondary structure, the interactions of the R groups give a protein its specific three-dimensional tertiary structure.
a) True
b) False
View Answer
Explanation: In the tertiary structure of a protein the interactions of the R groups give a protein its specific three-dimensional tertiary structure. Global but restricted to the amino acid polymer. Formed and stabilized by hydrogen bonding, covalent (e.g. disulfide) bonding, hydrophobic packing toward the core and hydrophilic exposure to solvent.
Sanfoundry Global Education & Learning Series – Drug and Pharmaceutical Biotechnology.
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