1. Which of the following forces is favorable for protein folding?
a) Hydrophobic interactions
b) Hydrogen bonding
c) Vander Waals forces
d) Ionic bonding
Explanation: Hydrophobic interactions aids in keeping protein stable and biologically active by allowing the protein to reduce its surface area.
2. A process by which a protein structure assumes its functional shape or conformation is?
a) Denaturing
b) Folding
c) Synthesis
d) Hydrolysis
Explanation: Proteins by folding into their 3-D conformation are able to perform their biological function.
3. Process of folding does not depend on ____________
a) Concentration of salts
b) pH
c) Solute
d) Solvent
Explanation: Process of folding depends on concentration of salts, pH and solvent.
4. Which of the following cannot denature a protein?
a) Iodoacetic acid
b) SDS detergent
c) Urea
d) Heating to 90°C
Explanation: Iodoacetic acid, an alkylating agent cannot denature the protein.
5. Which of the following is a function of chaperone protein?
a) It degrades proteins that have folded improperly
b) It provide a template for how the proteins should fold
c) It rescues proteins that have folded improperly and allows them to refold properly
d) It degrades proteins that have folded properly
Explanation: Molecular chaperons are proteins that interact with partially folded polypeptides, facilitating correct folding pathways in which folding can occur.
6. As folding progresses which of the following does not take place?
a) Entropy decreases
b) Amount of protein in native state increases
c) Free energy increases
d) Amount of protein in native state decreases
Explanation: As folding progresses, entropy decreases, amount of protein in native state increases and free energy increases.
7. Which of the following are chaperons in E.coli?
a) Hsp70
b) Hsp40
c) DnaA
d) DnaK and DnaJ
Explanation: Hsp70 and Hsp40 are chaperons in eukaryotes.
8. Which of the following about spontaneous folding is false?
a) It involves the initial formation of highly compact structure
b) It involves initial formation of a local secondary structure
c) It is essentially a random process
d) It may be defective in some human diseases
Explanation: Protein folding is a spontaneous process aided by the hydrophobic interactions which is not random.
9. Protein A will fold into its native state only when protein B is also present in the solution. However, protein B can fold itself into native confirmation without the presence of protein A. Which of the following is true?
a) Protein B serves as precursor for protein A
b) Protein B serves as molecular chaperon for protein A
c) Protein B serves as ligand for protein A
d) Protein B serves as structural motif for protein A
Explanation: Not all proteins fold spontaneously as they are synthesized in the cell. Folding for many proteins is facilitated by the action of specialized proteins known as molecular chaperons.
10. Which of the following is true about ribonucease?
a) Native state which is catalytically inactive is denatured
b) Unfolded state is inactive
c) Renatured ribonuclease is inactive
d) Renaturation involves reestablishment of the correct disulfide cross links
Explanation: Native is catalytically active and undergoes denaturation by the addition of urea and mercaptoetanol.