wgu c785 biochemistry performance assessment pa final exam test prep 20222023verified questions and answersa review
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WGU C785 BIOCHEMISTRY PERFORMANCE
ASSESSMENT (PA) FINAL EXAM TEST PREP 2022/2023
DNA replication is ___________, which allows each of the two strands to serve as a _______ for the new
strands.
b. semiconservative, template (correct answers)DNA replication is semiconservative, meaning that each
new duplex has one original (parent) strand and one new strand. Because the two parent strands are
separated during replication and the base pairing is predictable, each parent strand can serve as a
template for the new strand synthesis.
Which of the following enzymes does NOT assist the DNA polymerase on the lagging strand to overcome
its two problems? (Recall that the DNA polymerase can only make DNA in the 5'->3' direction, and it
must bind a double-stranded nucleotide polymer before it can start making its own DNA polymer.)
c. Helicase (correct answers)Helicase unwinds the double stranded DNA to allow for replication, but this
is not a problem for the DNA polymerase.
Several components of cigarette smoke, including benzopyrene, insert themselves (intercalate) into the
DNA and lead to several types of mutations such as frameshift mutations, including both insertions and
deletion. Which of the following repair pathways would be used to repair this type of damage?
c. Nucleotide Excision Repair (correct answers)Nucleotide excision repair is used to repair deletions,
insertions, and helix-distorting lesions, such as thymine dimers.
Maternal smoking during pregnancy is hazardous yet common in many places. Many studies have
associated prenatal smoking to unhealthy physical and psychological outcomes for the baby.
Researchers know that maternal smoking affects are epigenetic in nature. Which of the following events
can be considered epigenetic in nature?
,a. Changes in chromatin structure (correct answers)Frame shift mutations are a kind of mutations which
result from addition of deletion of a nucleotide base resulting in an altered reading frame and ultimately
a different protein, than the one the gene originally encoded. Frameshift mutations are genetic changes
because they alter the DNA sequence, whereas epigenetic changes do not alter the DNA sequence.
Epigenetic changes are modifications to genomic structure (not sequence) that are caused by the
external environment. These environmental factors affect the overall chromatin structure to allow more
or less "access" to the DNA by gene expression machinery to turn the genes "on" or "off". In other
words, epigenetics can alter gene expression without changing the underlying DNA sequences. The
changes may or may not be heritable, depending on the location and circumstances.
Blood type is an example of what type of inheritance?
a. Codominance (correct answers)The genes that produce the A and B antigen proteins can both be
expressed independently, and a heterozygote (someone with both genes) will be produce both A and B
proteins - neither will dominate the other. The is an example of codominance.
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?
a. 50% (correct answers)If D is the disease-conferring dominant allele and d is the normal allele, the
father has the genotype Dd and the mother's genotype is dd. Each child can only inherit a d allele from
their mother, and they have a 50% chance of inheriting the D allele from their father. As a result, the
expected probability that their child will inherit the disease is 50%.
The physical trait of lip protrusion exhibits a characteristic type of inheritance, as shown by the pedigree
above. What type of inheritance best describes this inheritance pattern?
a. Incomplete dominance (correct answers)The correct answer is incomplete dominance. The blending
of the large and small lip protrusion into an intermediate, medium lip protrusion, as well as the presence
of all three variations in the offspring, demonstrate a clear example of incomplete dominance.
, The normal sequence of a section of the HLA-B27 gene, a genetic marker of the inflammatory disease
Ankylosing spondylitis, is given below. Match each mutation of the sequence to the type of mutation it
exhibits. A genetic code table is provided for your use in answering the question.
5'- CGG CAG AAU UUA -3'
5'- CAG CAG AAU UUA -3' - Missense mutation
5'- CGG CAG AAA UUU A-3' - Insertion
5'- CGG CAG AAC UUA -3' - Silent mutation
5'- CGG CAG AAU UA -3' - Deletion
5'- CGG UAG AAU UUA-3' - Nonsense mutation (correct answers)Silent mutations are those in which the
amino acid encoded doesn't change as a result of the mutation.
Missense mutations are those in which the amino acid encoded changes to a different amino acid as a
result of the mutation.
Nonsense mutations are those in which the amino acid encoded changes to a stop codon as a result of
the mutation, yielding a smaller protein.
Insertions are the inclusion of extra nucleotides compared to the original sequence. They can result in
other mutations, such as nonsense mutations.
Deletions are the removal of nucleotides compared to the original sequence. They can result in other
mutations, such as nonsense mutations.
PCR is a powerful tool that can do all of the following....
b. detect mutations that lead to disease
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