Proteins and amino acids Knowledge-Based Download PDF

Questions

1. 1.

   Which level of protein structure is characterized by the assembly and specific spatial interaction of two or more distinct polypeptide subunits into a single functional macromolecule?

   • A) Tertiary structure
   • B) Quaternary structure
   • C) Secondary structure
   • D) Primary structure
2. 2.

   Which component of an amino acid molecule varies among the twenty standard biological amino acids and determines whether an amino acid behaves as hydrophobic, polar, acidic, or basic?

   • A) Amino group
   • B) Carboxyl group
   • C) Alpha hydrogen atom
   • D) Variable side chain (R group)
3. 3.

   When a functional globular protein undergoes denaturation, which level of protein structure is preserved intact because covalent peptide bonds are not broken?

   • A) Quaternary structure
   • B) Secondary structure
   • C) Primary structure
   • D) Tertiary structure
4. 4.

   Which chemical interaction is primarily responsible for stabilizing the secondary structures of a protein, such as alpha helices and beta-pleated sheets?

   • A) Hydrogen bonds between the carbonyl and amino groups of the polypeptide backbone
   • B) Disulfide bridges formed covalently between adjacent cysteine side chains
   • C) Hydrophobic interactions between nonpolar side chains clustered in the interior
   • D) Ionic bonds between positively and negatively charged variable R groups
5. 5.

   During the formation of a dipeptide through a condensation reaction, which functional groups directly react with each other to establish the peptide bond?

   • A) The amino group of one amino acid and the central alpha-carbon of the adjacent amino acid
   • B) The variable side chain of one amino acid and the carboxyl group of the adjacent amino acid
   • C) The carboxyl group of one amino acid and the amino group of the adjacent amino acid
   • D) The variable side chains of two adjacent amino acids