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WGU C785 Biochemistry Unit Exam Questions And Answers Verified Solutions
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WGU C785 Biochemistry Unit Exam QuestionsWhich level of protein structure is disrupted through the hydrolysis of peptide bonds?
Quaternary
Tertiary
Primary
Secondary Correct Answer: 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 Answer: 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 Answer: 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 Answer: 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 Answer: 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 Answer: Hydrogen bonding
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 Answer: 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 Answer: 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 Answer: 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 Answer: Alpha Carbon
The alpha carbon is the central carbon on an amino acid that holds together the other groups of the
amino acid. It is always attached to the amino group, the carboxyl group, the side chain, and a single
hydrogen. It is part of the backbone of the amino acid and is found in every amino acid.
Given the following amino acid structure, what is the strongest intermolecular force it would
participate in to stabilize a protein structure?
Ionic bond
Disulfide bond
Hydrogen bond
Hydrophobic interaction Correct Answer: Hydrophobic interaction
The amino acid pictured only has CH groups in its side chain, and therefore is non-polar. Non-polar
amino acids make hydrophobic interactions.
Which change would most likely result in a permanent modification of an expressed protein's
function?
An increase in the pH of a solution in which a protein is dissolved from 6.5 to 8.0, when it is known
that the protein has an optimal activity of pH 7.8
A mutation of the gene for a protein that leads to the substitution of a hydrophobic amino acid with a
nonpolar amino acid
A mutation of the gene for a protein that leads to the substitution of a nonpolar amino acid with a
charged amino acid
The mutation of a gene for an enzyme involved in protein synthesis following exposure to X-rays,
causing the protein not to be synthesized Correct Answer: A mutation of the gene for a protein that
leads to the substitution of a nonpolar amino acid with a charged amino acid.
The mutation of nonpolar amino acid to a charged amino acid will disrupt the original hydrophobic
interaction, permanently changing the function of the protein.
Which property of enzymes is illustrated in the final step of the enzymatic cycle?
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