WGU Biochemistry Final Review

1. The polymerase chain reaction is a tool used to study protein structure.

True

False correct answer- 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 correct answer- 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 correct answer- 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 correct answer- 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 correct answer- 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 correct answer- 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 correct answer- 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 correct answer- 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 correct answer- 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 correct answer- 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) correct answer- 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 correct answer- 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 correct answer- Will

have the disease

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