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WGU Biochemistry OA Review Questions And Answers
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WGU Biochemistry OA Review Questions AndAnswers
1. The polymerase chain reaction is a tool used to study protein structure.
True
False Ans - False
Feedback
PCR is a tool used to amplify a specific segment of DNA.
What color is the primer in the following diagram?
Red
Purple
Blue Ans - Red
Feedback
Recall from the section on DNA replication that DNA polymerase needs a
primer to begin DNA synthesis. This requirement means the primers will
direct the DNA polymerase to only synthesize complementary strands of the
target DNA. (Note: In DNA replication, the primers are RNA primers, while
PCR generally uses DNA primers because they are more stable.)
dNTPs are DNA nucleotides used in PCR.
True
False Ans - True
Feedback
dNTPs stands for deoxynucleotide triphosphates, which are the nucleotides
used in DNA synthesis.
A thermocycler is a machine used for PCR that varies the temperature of a
sample.
True
False Ans - True
Feedback
For PCR, in each cycle, the two strands of the duplex DNA are separated by
heating, then the reaction mixture is cooled to allow the primers to anneal
(or pair) to their complementary segments on the DNA. Next, the DNA
polymerase directs the synthesis of the complementary strands. The use of a
,heat-stable DNA polymerase eliminates the need to add fresh enzyme after
each round of heating (heat inactivates most enzymes). Hence, in the
presence of sufficient quantities of primers and dNTPs, PCR is carried out
simply by cycling through the different temperatures for strand separation,
primer annealing, and DNA synthesis.
The thermocycler is the machine that is used to vary the temperature of the
samples.
DNA polymerase is used in DNA replication and in PCR.
True
False Ans - True
Feedback
Both PCR and DNA replication require DNA polymerase to make new copies
of DNA.
Which of the following changes can NOT be detected using PCR?
Differences in DNA sequence
Epigenetic changes
Deletions
Insertions Ans - Epigenetic changes
Feedback
Epigenetic changes do not affect the sequence of the DNA. PCR is used to
look at the DNA sequence.
Which of the following components is NOT used in PCR?
DNA template
DNA nucleotides
RNA polymerase
Primers Ans - RNA polymerase
Feedback
PCR makes a DNA copy, so DNA polymerase is used.
Assuming there is one copy of the target DNA sequence before PCR, how
many copies of DNA are there after 5 PCR cycles?
256
6
65,536
16
32 Ans - 32
,Feedback
Each cycles double the numbers of DNA copy. Round 1: 1->2. Round 2: 2 -
>4. Round 3: 4 -> 8. Round 4: 8 ->16. Round 5: 16 ->32.
DNA polymerase can synthesize new DNA strands in which direction?
3' to 5'
5' to 3'
any direction
N-terminus to C-terminus Ans - 5' to 3'
Feedback
DNA needs a free 3' end to bind to and initiate synthesis of a DNA. It
synthesizes in a 5' to 3' direction.
The following are steps involved in a polymerase chain reaction. Which is the
correct order:
Elongation, denaturation, and annealing
Denaturation, annealing, and elongation
Annealing, elongation, and denaturation
Elongation, annealing, and denaturation Ans - Denaturation, annealing,
and elongation
Feedback
PCR uses repeated cycles of temperature to amplify particular DNA
segments. In the first step, the reaction mixture is heated to separate the
DNA strands (denaturation). The reaction is then cooled to allow the DNA
primers, which define the sequence to be amplified, to anneal (base pair)
with the template DNA. In the third step, DNA polymerase extends the DNA
primers to create a copy of the target DNA sequence. Heating the reaction to
stop polymerization and separate the DNA strands starts the cycle over
again
Sickle Cell Anemia is inherited in an autosomal recessive pattern. Choose the
set of chromosomes of a person that has inherited the disease. Green boxes
represent normal alleles and yellow boxes represent mutant alleles.
Captionless Image
A. Chromosome 12 (Blue) vs. Chromosome 11 (Red)
B. Chromosome X (Blue) vs. Chromosome Y (Red, Short)
C. Chromosome 11 (Blue) vs. Chromosome 11 (Red w/green stripe)
D. Chromosome 11 (Blue) vs. Chromosome 11 (Red w/yellow stripe) Ans -
D. Chromosome 11 (Blue) vs. Chromosome 11 (Red w/yellow stripe)
, Feedback
This question depicts chromosomes and asks which pair represents an
Autosomal Recessive inheritance pattern. Each of the chromosomes are
pictured carrying an allele from each parent, which is depicted by a yellow or
green box. The green box represents a normal or dominant allele, while the
yellow box represents a mutant or recessive allele.
An Autosomal trait will be carried on a numbered chromosome and both
chromosomes should have the same number. An X-linked trait will be carried
on an X-chromosome. This allows us to rule out answer choices A and B.
To inherit a recessive trait, we need to inherit two recessive (or mutant
alleles), which would be shown as two yellow boxes. A dominant trait can be
inherited when one or two dominant alleles are present. Answer choice C
depicts an Autosomal Dominant inheritance, while answer choice D is the
correct answer because it depicts an Autosomal Recessive inheritance
pattern.
Hemophilia is an X-linked recessive condition. This means that:
1. A person with at least one normal X chromosome without the hemophilia
gene will not show signs of hemophilia
2. The disease is more common in females
3. Affected men can pass the condition on to sons but not to daughters
4. Women can only pass the condition on to daughters Ans - 1. A person
with at least one normal X chromosome without the hemophilia gene will not
show signs of hemophilia
Feedback
An X-linked recessive condition is inherited when a female has a recessive
allele on each of her X chromosomes. Males inherit an X-linked recessive
condition if they inherit a recessive allele on their one and only X
chromosome. Therefore if a female has a dominant (or normal) allele on one
of her X chromosomes, she will not have the disease.
Because men only have one X-chromosome, they tend to inherit X-linked
conditions more easily than females.
Men with X-linked recessive conditions do not pass the disease on to their
sons, because they pass a Y chromosome on to their sons. Men will pass an X
chromosome to their daughters.
Women are able to pass an X chromosome on to their son or their daughters.
A woman is homozygous for an abnormal allele on Chromosome 2 that codes
for an autosomal dominant disease. This means that she:
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