WGU C785 BIOCHEMISTRY UNIT EXAM QUESTIONS 2023 VERIFIED QUESTIONS AND ANSWERS ALREADY PASSED

Which level of protein structure is disrupted through the hydrolysis of peptide bonds? Quaternary Tertiary Primary Secondary - CORRECT ANS Primary The primary structure of a protein is the sequence of amino acids held together by peptide bonds. Peptide bonds are formed by dehydration reactions and disrupted by hydrolysis. A mutation in the beta-hemoglobin gene, which results in the replacement of the amino acid glutamate in position 6 with the amino acid valine, leads to the development of sickle cell anemia. The structures of glutamate and valine are shown below. If the beta hemoglobin gene in a patient with sickle-cell anemia were to be edited so that the valine in position 6 was replaced with a different amino acid, which replacement for valine would be expected to have the best clinical outcome, in theory, for the patient? (Assume the valine can potentially be replaced with any amino acid other than glutamate.) - CORRECT ANS The original amino acid in a healthy patient is glutamate, which is negatively charged. The mutated amino acid is valine, which is non-polar. Valine is causing sickle cell anemia. The best amino acid to replace valine so that the patient is healthy again would be the one most like glutamate, so any negatively charged amino acid. Secondary, tertiary, and quaternary levels of protein structure can all be impacted by exposing a protein to which treatment? Change of a hydrophobic amino acid to a different hydrophobic amino acid Addition of a reducing agent Placement of the protein in a solution with a low pH Increase in the concentration of the protein in solution - CORRECT ANS Placement of the protein in a solution with a low pH Changes in pH affect hydrogen bonds and ionic bonds. Hydrogen bonds in the backbone of amino acids occur in secondary structure, and both hydrogen bonds and ionic bonds occur in the side chains of amino acids in tertiary structure. An increase in beta-pleated sheet structure in some brain proteins can lead to an increase in amyloid deposit formation, characteristic of some neurodegenerative diseases. What is the primary biochemical process that follows the increase in beta-pleated sheet structure that leads to the development of the amyloid deposits? An increase in glycogen formation in the brain cells Aggregation of the proteins in the brain Secretion of glucagon, leading to excessive ketogenesis An increase in anaerobic metabolism of glucose in the brain - CORRECT ANS Aggregation of the proteins in the brain This question is describing changes in protein structure. Aggregation occurs when proteins clump together inappropriately, causing plaques like amyloid deposits to accumulate. Which level of protein structure is determined by the sequence of amino acids? Secondary structure Quaternary structure Tertiary structure Primary structure - CORRECT ANS Primary structure The primary structure of a protein is simply the sequence of amino acids held together by peptide bonds. Which force is most influential in determining the secondary structure of a protein? Hydrophobic effect Disulfide bonding Hydrogen bonding Electrostatic interactions - CORRECT ANS Hydrogen bonding