WGU C785 BIOCHEMISTRY OBJECTIVE ASSESSMENT
(OA) FINAL EXAM 2022/2023
Which level of protein structure is disrupted through the hydrolysis of peptide bonds?
Quaternary
Tertiary
Primary
Secondary (correct answers)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 answers)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 answers)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 answers)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?
, The secondary structure of a protein is built by hydrogen bonds between the carboxyl groups and amino
groups on the backbones of the amino acids.
Which amino acid would most likely participate in hydrogen bonds? (correct answers)Amino Acid
structure 4
This is a polar, uncharged amino acid due to the OH group on the side chain. Polar, uncharged amino
acids containing oxygen or NH groups make hydrogen bonds.
Which portion of the amino acid is inside the box?
The box is surrounding the section below the Alpha Carbon (correct answers)Side Chain
The side chain is the variable group of the amino acid, also called the R group. Every amino acid has the
same amino group, carboxylic acid group, and an alpha carbon, but the side chain is different.
Which pair of amino acids will most likely interact through hydrophobic forces between their side
chains? (correct answers)Both of these amino acids are non-polar and therefore can interact together
with a hydrophobic interaction. Please note that the "S" in the amino acid on the right is non-polar,
while the "SH" group in answer choice D is polar. The S must have an H to be polar and is otherwise non-
polar.
Which portion of the amino acid is inside the box?
The box is over the Carbon at the Center of the chain (correct answers)Alpha Carbon
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