Lecture 6 Quiz

What does the thermodynamic hypothesis state about protein folding?

• Protein folding is solely determined by external factors
• Folding is influenced only by protein sequence.

• Protein folding is a random process with no specific driving force
• Protein folding is not influenced by energetically favorable interactions

Christian Anfinsen received the Nobel Prize for his work on:

• DNA replication
• Quantum mechanics
• Cell division
• Protein folding

Denaturing agents like urea disrupt protein folding by:

• Enhancing protein stability
• Promoting proper protein folding
• Strengthening hydrogen bonds and other non-covalent interactions
• Breaking hydrogen bonds and other non-covalent interactions

The native structure of ribonuclease-A can be recovered after denaturation by:

• Increasing temperature.

• Adding more urea.

• Removing urea in the presence of oxygen.

• Detonation

What is the consequence of forming disulfide bonds in the presence of urea according to Anfinsen's experiment?

• Increased catalytic activity.

• No change in protein function.

• Formation of a new protein structure
• Scrambled disulfide bonds with low activity.

What happens to the folding of ribonuclease-A when the disulfide bonds are allowed to form in the absence of urea?

• Ribonuclease-A will denature completely
• Ribonuclease-A will form a different protein
• Ribonuclease-A will fold correctly into its native conformation.
• Ribonuclease-A will degrade

How many possible combinations of disulfide pairings exist for ribonuclease-A with eight cysteine residues after corrections?

• 40320

• 2520

• 105

• 44

The decrease in protein entropy during folding:

• Promotes folding.

• Opposes folding.

• Has no effect on folding.

• Increases folding rate.

A major driving force underlying protein folding is:

• Ionic bonding.

• The hydrophobic effect.

• Covalent bonding.

• Love

Hydrophobic groups in proteins affect water entropy by:

• Increasing the entropy of water molecules.

• Decreasing the entropy of water molecules.

• No effect on water entropy.

• Breaking water molecules apart.