Biochemistry C785 Readiness Check 2020 –
Western Governors University
Biochemistry Readiness Check
The 2nd OA Readiness Check is designed to give you
... [Show More] additional practice with new
assessment-style questions to help prepare for success on the OA. Thus, please try to
mimic exam-like conditions by taking the test in one <2 hr sitting without any study aids
apart from your whiteboard/scrap paper. Note: Responses cannot be edited. You will be
able to see the results and feedback after submitting the test. A score of 70% is required
for OA approval. If you score below 70%, please speak with a Course Instructor via
appointment to discuss next steps prior to retaking this test.
Points:
54/67
1
What is the complementary sequence to 3’ ATG CGA ATA 5’?
(1/1 Points)
3’ TAT TCG CAT 5’
The correct answer is 3' TAT TCG CAT 5'. Remember complementary means “Matching
or Pairing” You have to remember to pay attention to your numbers as well as your
letters (A-T, G-C, 5'-3'). The correct answer is 3’ ATG CGA ATA 5’ (original sequence) 5’
TAC GCT TAT 3’ (complementary sequence) But we asked for it in the 3’ direction, so
mirror answer to give correct answer: 3’ TAT TCG CAT 5’
3’ TAC GCT TAT 5’
3’ GAT AGC ATA 5’
5’ ATA AGC GTA 3’2
Which amino acid sequence would result from this Coding DNA strand? 3’ ATG CAG
ATA 5’?
(0/1 Points)
Tyr Val Tyr
The correct answer is Ile Asp Val. We are starting at the coding strand, and have to
remember the relationship between coding DNA and mRNA. These two strands are
non-complementary and parallel. So we copy the coding strand , change T ---> U, and
then write the mRNA sequence: 3’ ATG CAG ATA 5’ coding 3’ AUG CAG AUA 5’
mRNA Mirror by changing orientation: 5’ AUA GAC GUA 3’ Read chart Ile Asp Val
(chart is in direction of 5' ---> 3') If you chose Tyr Val Tyr, this answer is incorrect
because this is the amino acid sequence that results from the mRNA 5' UAC GUC UAU
3' which would have been complementary to the given coding strand. Coding DNA is
non-complementary and parallel to mRNA.
Ile Gln Ile
Ile Asp Val
Leu His Lys
3
Which amino acid sequence would be made from this template DNA strand? 5’ TAT TAC
CGA 3’?
(1/1 Points)
Tyr Tyr Arg
Ile Met Ala
Ser Val Ile
The correct answer is Ser Val Ile because 5’ TAT TAC CGA 3’ template is complementary
and antiparallel so 3’ AUA AUG GCU 5’ but it is in the wrong orientation, so mirror 5’
UCG GUA AUA 3’ and read the chart Ser Val Ile
Ser His Gln
4Which of the following are the correct components for a PCR reaction?
(1/1 Points)
dNTPs, Primer, RNA Polymerase, template RNA
dNTPs, Primer, DNA Polymerase, template DNA
The correct answer is dNTPs, Primer, DNA Polymerase, template DNA. Notice that all
components are about DNA. The Primer is even a DNA Primer.
ATP, Primer, mRNA polymerase; template mRNA
Acetyl CoA, RNA primer, DNA Ligase, Template phosphate
5
Assuming 100% reaction efficiency, how many DNA copies will be produced after 5 PCR
cycles, if we begin with 1 DNA template?
(1/1 Points)
16
32
The correct answer is 32. 2x2x2x2x2=32
64
10
6
Which of the following would represent a silent mutation if this is the original sequence:
5’ AUC GUA ACA 3’?
(1/1 Points)
5’ AUC GGA ACA 3’
5' AUA GUA ACA 3'
The correct answer is 5' AUC GUA ACA 3' Ile Val Thr
5’ AUG GUA ACA 3’
5’ AUC GCA ACA 3’
7If the original coding sequence is 5’ CGA TAC TTC AGA 3’ and it is mutated to 5' CGA
TAT TTC AGA 3', what type of mutation would have taken place?
(0/1 Points)
Silent
Missense
The correct answer is silent mutation. The nucleotide sequence changes, but it codes for
the same amino acid. The coding sequence 5' TAC 3' corresponds to the mRNA sequence
5' UAC 3' (Tyr), and the coding sequence 5' TAT 3' corresponds to the mRNA sequence
5' UAU 3' (Tyr). Since the C changed to at T, this is a point mutation. If the point
mutation results in the same amino acid in the new sequence as in the original
sequence, the point mutation is a silent mutation.
Nonsense
Insertion
8
This learning objective is now tested in a different WGU course than Biochemistry.
Please select True.
True
The correct answer is Option 1 because an autosomal dominant disorder would be
inherited on numbered chromosomes, not sex chromosomes X or Y. Also, at least one
dominant allele (yellow box) needs to be present for the individual to have the dominant
disease.
False
9
This learning objective is now tested in a different WGU course than Biochemistry.
Please select True.
True
The correct answer is X- linked recessive because parents (carriers) do not have it (II-5-
6) but a child does (III-5). You will get the same result if you consider parents (carriers)
(I-1-2), who do not have the trait, but a child does (II-3). A third option that gives thesame result (X-linked recessive) is by considering parents (carriers) who do not have the
trait (III-1-2), and their child does (IV-1). The pattern is recessive because the selected
parents are carriers, and it is X-linked because only males have the trait.
False
10
This learning objective is now tested in a different WGU course than Biochemistry.
Please select True.
True
The correct answer is 50%. Homozygous recessive: aa Heterozygous: Aa When you see
"percentage" or "probability," think Punnett square. 50% of the children would be
expected to be Aa, and 50% of the children would be expected to be aa.
False
11
Which of the following describes an epigenetic change?
(0/1 Points)
Denaturation of template DNA to facilitate primer annealing.
Increased methylation of the promoter region of a tumor suppressor gene in a
developing fetus.
Thymine dimer formation resulting from UV radiation.
The correct answer is "Increased methylation of the promoter region of a tumor
suppressor gene in a developing fetus."
Mismatch mutation caused by mistakes made by DNA Polymerase during
replication.
12
Rett syndrome is a brain disorder that occurs almost exclusively in females, causing
severe deficits in language, learning, coordination and other brain functions. Decreased
expression of the MECP2 gene causes Rett syndrome. Which of the following scenarios
correctly describes how Rett syndrome could be developed?
(0/1 Points)A DNA-binding protein blocks RNA Polymerase from binding to the promoter
sequence, facilitating the transcription of the MECP2 gene.
The answer is "Transcription factors are unable to bind to the transcription start site of
the MECP2 gene because nucleosomes are tightly packed together." Think "increased
space gives increased access and increased expression." Gene expression is increased
when nucleosomes are widely spaced and transcription factors and RNA Polymerase are
able to bind to the transcription start site of the gene. In this question, decreased
expression is resulting from decreased space between the nucleosomes, so the RNA
Polymerase and transcription factors have decreased access to the transcription start
site of the gene. If you answered, "A DNA-binding protein blocks RNA Polymerase from
binding to the promoter sequence, facilitating the transcription of the MECP2 gene,"
this answer is incorrect. Transcription factors are proteins that bind to the promoter
region on the 5' side of the gene to be expressed. The RNA Polymerase then binds to the
transcription start site.
Transcription factors are unable to bind to the transcription start site of the MECP2
gene because nucleosomes are tightly packed together.
Transcription activators cause nucleosomes to separate, exposing the MECP2 gene.
RNA Polymerase binds to the MECP2 gene and begins translation.
13
What happens when the incorrect base is added during the synthesis of a DNA strand in
DNA replication?
(1/1 Points)
The homologous chromosome is used to replace the incorrectly added base with the
correct one.
DNA Polymerase removes the incorrect base and adds in the correct base.
The correct answer is "DNA Polymerase removes the incorrect base and adds in the
correct base." DNA Polymerase repairs mismatch errors that occur during DNA
replication.
Thymine dimers occur.Distortion of the double helix occurs and is repaired by RNA Polymerase.
14
What is the correct definition of nucleotide excision repair?
(1/1 Points)
Removal of a single damaged nucleotide
Damage to a few or several nucleotides are identified, then many nucleotides are
removed and all are replaced to repair the DNA segment
The correct answer is "Damage to a few or several nucleotides are identified, then many
nucleotides are removed and all are replaced to repair the DNA segment." In nucleotide
excision repair, several nucleotides are removed whereas, in BER (base excision repair),
a single nucleotide is removed.
Required when there are breaks in the double stranded DNA strand which causes
discontinuity in both strands
Insertion of a thymine dimer
15
If arginine is mutated to leucine within a protein, how would the structure of the protein
be affected?
(1/1 Points)
Ionic bonds will continue to form, allowing the protein to fold as normal.
Hydrophobic interactions will continue to occur resulting in normal folding.
Ionic bonds will no longer form, potentially causing the protein to misfold.
The correct answer is "Ionic bonds will no longer form, potentially causing the protein
to misfold." Since arginine is a positively-charged amino acid, it would have formed an
ionic bond with a negatively-charged amino acid in the protein. Leucine is not charged
and is hydrophobic, so it will not form this same ionic bond, and could lead to protein
misfolding.
Hydrophobic interactions will be broken, potentially causing aggregation.
16Which pair of amino acids below could bond together to stabilize the tertiary structure
of a protein?
(0/1 Points)
Option 1
Option 2
The correct answer is "phenylalanine" and "methionine." Phenylalanine and methionine
are both nonpolar (hydrophobic) amino acids, and they interact in the core of the
protein through hydrophobic forces.
Option 3
Option 4
17
On a summer's day, I was cleaning my garage. My cat Sophie was out with me, and got
into a bottle containing a strong reducing agent. Of course I took her straight to the vet.
What type of amino acid bonds would be disrupted by exposure to the strong reducing
agent?
(1/1 Points)
Hydrophobic interactions
Hydrogen bonds
Disulfide bonds
The correct answer is covalent (disulfide) bonds. Hydrophobic interactions are
disrupted by heat. Hydrogen bonds and ionic bonds are both disrupted by pH and by
salt.
Ionic bonds
18
What type of bond can the amino acids below form to stabilize the tertiary structure of a
protein?
(0/1 Points)
Ionic bondThe correct answer is "hydrogen bond." Each of the amino acids shown is a polar amino
acid, and polar amino acids interact through hydrogen bonds. The NH combined with
the C=O in glutamine places this amino acid side chain into the polar category. The OH
bond in serine places this amino acid side chain into the polar category.
Hydrophobic interaction
Hydrogen bond
Disulfide bond
19
What type of reaction forms the primary structure of a protein?
(1/1 Points)
Activation energy
Enzymes
Dehydration
The correct answer is a dehydration reaction. When two amino acids join together, they
lose water. One loses an O from a carboxyl group, and the other loses two Hs from its
amino group, to give a loss of water. See Study Guide Step 7 for review.
Hydrolysis
20
Myoglobin is an oxygen storage protein and exhibits a hyperbolic curve in an oxygen
saturation graph. What is the highest level of protein structure exhibited by myoglobin?
(1/1 Points)
Primary
Secondary
Tertiary
The correct answer is "tertiary." Myoglobin is made from one polypeptide chain, or is a
"single subunit" protein. Myoglobin's tertiary structure gives it its functional 3D shape.
A hyperbolic curve indicates a "single subunit" protein. A sigmoidal curve indicates a
quaternary (multi-subunit) protein.Quaternary
21
What level of protein structure involves alpha helices and beta pleated sheets?
(1/1 Points)
Primary
Secondary
The secondary level has alpha helices and beta pleated sheets. Primary structure is
formed by joining together amino acids through peptide bonds. Secondary structure is
formed by hydrogen bonds between backbone amino acids. Tertiary structure is formed
form interactions between amino acid side chains. Quaternary structure is formed from
interactions between amino acid side chains. Proteins with quaternary structure have
two or more subunits.
Tertiary
Quaternary
22
Glutamine is located at position 13, of a protein, and forms a hydrogen bond with the
amino acid at position 89. What would happen if the amino acid at position 89 was
mutated to alanine?
(1/1 Points)
Nothing, they will bind normally
The hydrogen bond will no longer be formed, and the protein will be misfolded
The correct answer is "The hydrogen bond will no longer be formed, and the protein will
be misfolded. Glutamine is a polar amino acid (NH and also C=O), and alanine is a
nonpolar (hydrophobic) amino acid (CH3), and so alanine will not interact with the
polar amino acid glutamine.
Nothing, they will form a hydrophobic interaction
They will form a disulfide bond
23An elderly patient is diagnosed with Alzheimer’s Disease. Which of the following is most
likely the cause of this neurological disorder?
(1/1 Points)
Disulfide bond formation by cysteine amino acids
Iron deficiency
Aggregation of hydrophobic amino acids
The correct answer is "Aggregation of hydrophobic amino acids." Alzheimer's disease
results from abnormal protein aggregation in the brain.
Ionic bonds formed by hydrogen bonding of amino acids [Show Less]