QQ-3

How do hydrophobic amino acids behave within a protein's structure?

• They form hydrogen bonds with water molecules.

• They are found on the protein's surface, interacting with water.

• They cluster together in the interior of proteins, away from water.

• They are evenly distributed throughout the protein.

Why are uncharged polar amino acids more likely to be found on the surface of proteins rather than in the protein's hydrophobic core?

• They are too large to fit in the core.

• They have a net positive charge.

• They interact favorably with hydrophobic molecules.

• They form hydrogen bonds with water and other polar molecules.

Which amino acid has a side chain consisting of just a single hydrogen atom, making it highly flexible and often referred to as a "flexible hinge" in protein structures?

• Glycine (Gly)

• Proline (Pro)

• Alanine (Ala)

• Threonine (Thr)

What distinguishes charged polar amino acids from other amino acids at physiological pH?

• They have large side chains.

• They have a net electric charge.

• They lack polar functional groups.

• They are highly hydrophobic.

Why is histidine considered important in various biological processes, especially in proteins and enzymes?

• It provides structural stability to proteins.

• It serves as an energy source for cellular respiration.

• Its dual ionization state allows it to function as a buffer and participate in proton transfer reactions.

• It regulates DNA replication in the cell.

Which of the following are the two most common secondary structures found in proteins?

• Alpha helices and beta strands.

• Alpha helices and beta sheets.

• Beta helices and gamma sheets.

• Gamma helices and alpha sheets.