WGU Biochemistry OA Review 2023
1. The polymerase chain reaction is a tool used to study protein structure.
True
False Ans - False
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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
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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
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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
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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
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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
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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
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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
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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'
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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
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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)
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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
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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:
Will have the disease
Will not have the disease
Has one normal gene and one abnormal gene
Can pass on two genes to any daughters and one gene to any son Ans - Will have the disease
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Homozygous means that the woman will have two copies of the abnormal allele. An abnormal allele is the allele that can lead to disease. Since the disease is dominant, then the abnormal allele is dominant in this case. With two copies of a dominant allele, an individual will inherit a dominant disease.
Mutations in the FANCA gene (located on chromosome 16) can lead to Fanconi
Anemia. A healthy individual inherited one mutant and one normal allele of the FANCA gene. Which of the following describes the inheritance pattern of Fanconi Anemia?
Autosomal Dominan t
Autosomal Recessive
X-linked Dominant
X-linked Recessive Ans - Autosomal Recessive
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Chromosome 16 is an autosome because it is a numbered chromosome. For a healthy individual to have a mutant allele, the mutant allele must be recessive.
A black female mouse mates with a white male mouse and produces a litter of all gray mice. Which inheritance pattern can be used to describe this situation?
Complete Dominance
Recessive
Incomplete Dominance
Codominance Ans - Incomplete Dominance
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Incomplete dominance produces a blended phenotype.
Both pedigrees show the inheritance of von Willebrand disease, a bleeding disorder in which platelets fail to clot properly. There are different types of von Willebrand disease that exhibit different inheritance patterns. Type I is inherited in an autosomal dominant fashion, while type III is autosomal recessive. Which of the following statements best describes the families depicted in the pedigrees below?
Family 1 has type III and Family 2 is unlikely to have either of these two types.
Family 1 has type I and Family 2 has type III Both families have type I.
Family 1 has type III and Family 2 has type I Ans - Family 1 has type III and
Family 2 has type I
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Family 1 has carrier parents present and both males and females are affected, so it is type III, autosomal recessive. Family 2 does not have carrier parents and affected males do have unaffected daughters, so it is type I, autosomal
dominant.
What is the expected probability that a child will have an autosomal dominant
disease if their father is heterozygous for the allele and their mother is
homozygous for the normal allele?
0%
25%
50%
100% Ans - 50%
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Aa X aa => 50% Aa diseased, 50% aa normal
Craniofrontonasal Dysplasia is an X-linked Dominant disorder. This condition is very rare and is caused by mutations in the Ephrin B-1 gene. Which one of the following pedigrees portrays the familial inheritance pattern of this X-linked Dominant disorder?
Option 1
Option 2
Option 3
Option 4 Ans - Option 4
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To first differentiate between dominant and recessive, check to see if any carriers are present in any generation. Options 1 and 3 are Recessive inheritance patterns because they both contain the pattern where two parents are unaffected and have a child that is affected. Option 1 is X-linked Recessive because only males are affected in the entire pedigree. Option 3 is Autosomal Recessive because there is an affected female. Since Options 2 and 4 are both Dominant, we look to see which one has a pattern where an affected father has daughters that are all affected. Option 2 has an affected father with an affected son, so this must be Autosomal Dominant. Option 4 demonstrates an affected father passing the disease down to all of his daughters, so the answer is Option
4.
Two healthy individuals give birth to a child that has Bloom Syndrome. From this information, it can be concluded that Bloom syndrome is inherited in a ________ manner.
recessive dominant
sex-linked Ans - recessive
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Carrier parents are parents who do not have a particular trait, such as a disease, but that trait shows up in their offspring. The presence of carrier parents signifies that the trait is recessive.
The Punnett Squares below represent three different types of dominance. Which
answer choice correctly identifies the different types of Dominance?
1. A. Complete Dominance; B. Incomplete Dominance; C. Codominance
2. A. Codominance; B. Complete Dominance; C. Incomplete Dominance
3. A. Incomplete Dominance; B. Complete Dominance; C. Codominance
4. A. Codominance; B. Incomplete Dominance; C. Complete Dominance Ans -
3. A. Incomplete Dominance; B. Complete Dominance; C. Codominance
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A. Incomplete Dominance (heterozygotes are a color in-between the dominant and recessive color). B. Complete Dominance (All flowers are completely the dominant color or the recessive color). C. Codominance (heterozygotes are both the dominant and the recessive color).
Match the letters with the correct names of the processes of the central dogma
(Replication; Transcription; Translation).
1. A) Transcription, B) Translation, C) Replication 2. A) Translation, B) Replication, C) Transcription
3. A) Replication, B) Transcription, C) Translation
4. A) Translation B)Transcription, Replication Ans - 3. A) Replication, B)
Transcription, C) Translation
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Correct! The central dogma starts with DNA, which is able to be replicated to prepare for cell division. DNA in the nucleus can also be accessed and [Show Less]
