WGU 785 Final Exam Latest 2026 With Complete Solution
Q1: Hemophilia Pedigree – Father has hemophilia, mother does not.
What is the outcome for their children?
Answer: All daughters will be carriers. Sons will not inherit hemophilia.
Rationale: Hemophilia is an X-linked recessive disorder. Fathers pass
their X chromosome to daughters and Y chromosome to sons. Since
the mother is unaffected and not a carrier, sons receive a normal X
from her, and daughters receive the father's affected X but are
protected by the mother's normal X.
Q2: Autosomal dominant inheritance pattern:
Answer: Males and females are equally affected. Affected individuals
typically have one affected parent. Non-carrier parents do not produce
affected offspring.
Rationale: Autosomal dominant traits require only one copy of the
mutant allele. There is no sex predilection, and the trait appears in
every generation.
Q3: What is polymerase chain reaction (PCR)?
Answer: PCR is a laboratory technique that amplifies specific DNA
sequences. It requires template DNA, nucleotides (dNTPs), heat-stable
DNA polymerase, and short oligonucleotide primers.
Rationale: PCR enables exponential amplification of targeted DNA
regions. Each component serves an essential function: template
,provides the sequence, nucleotides are building blocks, polymerase
catalyzes synthesis, and primers define the amplification boundaries.
Q4: What are the three steps of PCR?
Answer: 1. Denaturation: heating to 95°C separates double-stranded
DNA. 2. Annealing: cooling to approximately 50°C allows primers to bind
complementary sequences. 3. Elongation: heating to 72°C enables DNA
polymerase to extend primers, synthesizing new strands. Rationale:
Thermal cycling exploits temperature-dependent DNA denaturation and
polymerase activity. Repeated cycles exponentially amplify the target
sequence.
Q5: What is Base Excision Repair (BER)?
Answer: BER repairs damage to individual bases caused by reactive
molecules. DNA glycosylase recognizes and removes the damaged
base. DNA polymerase inserts the correct nucleotide, and DNA ligase
seals the backbone.
Rationale: BER corrects non-bulky lesions such as deamination or
oxidation. It removes only the damaged base, not the entire nucleotide,
making it a precise repair mechanism.
Q6: When does Mismatch Repair (MMR) occur?
Answer: MMR occurs during DNA replication immediately after
synthesis.
Rationale: DNA polymerase proofreads but occasionally incorporates
incorrect bases. MMR recognizes mismatches on the newly synthesized
,strand, excises a segment containing the error, and allows polymerase
to resynthesize correctly.
Q7: What type of DNA damage does Mismatch Repair correct? Answer:
MMR corrects base-base mismatches and small insertiondeletion loops
that escape proofreading during replication, such as G-T instead of G-
C.
Rationale: MMR distinguishes the newly synthesized strand from the
template using transient nicks or methylation patterns. Defects in MMR
cause microsatellite instability and increase cancer risk.
Q8: What happens when DNA polymerase binds to DNA to make RNA?
Answer: This is transcription. RNA polymerase binds to the template
DNA strand and synthesizes complementary RNA using ribonucleotides.
Rationale: Transcription is the first step of gene expression. Unlike
DNA polymerase, RNA polymerase does not require a primer and can
initiate synthesis de novo.
Q9: What is needed for DNA replication?
Answer: DNA replication requires DNA polymerase, template DNA,
primers, deoxynucleotide triphosphates (dNTPs), and accessory
proteins such as helicase and ligase.
Rationale: DNA polymerase cannot initiate synthesis without a primer.
It extends existing strands in the 5'→3' direction, requiring continuous
and discontinuous synthesis on leading and lagging strands.
, Q10: What is a nonsense mutation?
Answer: A single nucleotide change that creates a premature stop
codon, truncating the protein product.
Rationale: Nonsense mutations produce shortened, often nonfunctional
proteins. They are called "nonsense" because the genetic message is
terminated prematurely.
Q11: What is a silent mutation?
Answer: A nucleotide change that does not alter the amino acid
sequence due to the degeneracy of the genetic code.
Rationale: Silent mutations occur in the third codon position (wobble
position) where multiple codons specify the same amino acid. They
typically have no phenotypic effect.
Q12: What is a missense mutation?
Answer: A nucleotide change that results in a different amino acid
being incorporated into the protein.
Rationale: Missense mutations alter the primary sequence. The
phenotypic consequence depends on the chemical similarity between
the original and substituted amino acid.
Q13: What happens during RNA splicing?
Answer: Introns (non-coding sequences) are removed from the
premRNA transcript, and exons (coding sequences) are ligated
together to form mature mRNA.
Q1: Hemophilia Pedigree – Father has hemophilia, mother does not.
What is the outcome for their children?
Answer: All daughters will be carriers. Sons will not inherit hemophilia.
Rationale: Hemophilia is an X-linked recessive disorder. Fathers pass
their X chromosome to daughters and Y chromosome to sons. Since
the mother is unaffected and not a carrier, sons receive a normal X
from her, and daughters receive the father's affected X but are
protected by the mother's normal X.
Q2: Autosomal dominant inheritance pattern:
Answer: Males and females are equally affected. Affected individuals
typically have one affected parent. Non-carrier parents do not produce
affected offspring.
Rationale: Autosomal dominant traits require only one copy of the
mutant allele. There is no sex predilection, and the trait appears in
every generation.
Q3: What is polymerase chain reaction (PCR)?
Answer: PCR is a laboratory technique that amplifies specific DNA
sequences. It requires template DNA, nucleotides (dNTPs), heat-stable
DNA polymerase, and short oligonucleotide primers.
Rationale: PCR enables exponential amplification of targeted DNA
regions. Each component serves an essential function: template
,provides the sequence, nucleotides are building blocks, polymerase
catalyzes synthesis, and primers define the amplification boundaries.
Q4: What are the three steps of PCR?
Answer: 1. Denaturation: heating to 95°C separates double-stranded
DNA. 2. Annealing: cooling to approximately 50°C allows primers to bind
complementary sequences. 3. Elongation: heating to 72°C enables DNA
polymerase to extend primers, synthesizing new strands. Rationale:
Thermal cycling exploits temperature-dependent DNA denaturation and
polymerase activity. Repeated cycles exponentially amplify the target
sequence.
Q5: What is Base Excision Repair (BER)?
Answer: BER repairs damage to individual bases caused by reactive
molecules. DNA glycosylase recognizes and removes the damaged
base. DNA polymerase inserts the correct nucleotide, and DNA ligase
seals the backbone.
Rationale: BER corrects non-bulky lesions such as deamination or
oxidation. It removes only the damaged base, not the entire nucleotide,
making it a precise repair mechanism.
Q6: When does Mismatch Repair (MMR) occur?
Answer: MMR occurs during DNA replication immediately after
synthesis.
Rationale: DNA polymerase proofreads but occasionally incorporates
incorrect bases. MMR recognizes mismatches on the newly synthesized
,strand, excises a segment containing the error, and allows polymerase
to resynthesize correctly.
Q7: What type of DNA damage does Mismatch Repair correct? Answer:
MMR corrects base-base mismatches and small insertiondeletion loops
that escape proofreading during replication, such as G-T instead of G-
C.
Rationale: MMR distinguishes the newly synthesized strand from the
template using transient nicks or methylation patterns. Defects in MMR
cause microsatellite instability and increase cancer risk.
Q8: What happens when DNA polymerase binds to DNA to make RNA?
Answer: This is transcription. RNA polymerase binds to the template
DNA strand and synthesizes complementary RNA using ribonucleotides.
Rationale: Transcription is the first step of gene expression. Unlike
DNA polymerase, RNA polymerase does not require a primer and can
initiate synthesis de novo.
Q9: What is needed for DNA replication?
Answer: DNA replication requires DNA polymerase, template DNA,
primers, deoxynucleotide triphosphates (dNTPs), and accessory
proteins such as helicase and ligase.
Rationale: DNA polymerase cannot initiate synthesis without a primer.
It extends existing strands in the 5'→3' direction, requiring continuous
and discontinuous synthesis on leading and lagging strands.
, Q10: What is a nonsense mutation?
Answer: A single nucleotide change that creates a premature stop
codon, truncating the protein product.
Rationale: Nonsense mutations produce shortened, often nonfunctional
proteins. They are called "nonsense" because the genetic message is
terminated prematurely.
Q11: What is a silent mutation?
Answer: A nucleotide change that does not alter the amino acid
sequence due to the degeneracy of the genetic code.
Rationale: Silent mutations occur in the third codon position (wobble
position) where multiple codons specify the same amino acid. They
typically have no phenotypic effect.
Q12: What is a missense mutation?
Answer: A nucleotide change that results in a different amino acid
being incorporated into the protein.
Rationale: Missense mutations alter the primary sequence. The
phenotypic consequence depends on the chemical similarity between
the original and substituted amino acid.
Q13: What happens during RNA splicing?
Answer: Introns (non-coding sequences) are removed from the
premRNA transcript, and exons (coding sequences) are ligated
together to form mature mRNA.
