a. c A nucleus
1. An aide asks the nurse why people who have neurofibromatosis will show varying degrees of the disease. Which genetic principle
... [Show More] should the nurse explain to the aide?
a. Penetrance
b. Expressivity
c. Dominance
d. Recessiveness
ANS: B
Expressivity is the extent of variation in phenotype associated with a particular genotype. For neurofibromatosis, a variety of manifestations occur among individuals. The penetrance of a trait is the percentage of individuals with a specific genotype who also exhibit the expected phenotype. Dominance refers to observable traits and risk of transmission. Recessiveness refers to silent strains with reduced risk of occurrence.
2. Cystic fibrosis is caused by what gene abnormality?
a. X-linked dominant
b. X-linked recessive
c. Autosomal dominant
d. Autosomal recessive
ANS: D
Cystic fibrosis is an autosomal recessive disorder. It is not a result of X links or dominant pathology.
3. A 15-year-old female is diagnosed with Prader-Willi syndrome. This condition is an example of:
a. genomic imprinting.
b. an autosomal recessive trait.
c. an autosomal dominant trait.
d. a sex-linked trait.
ANS: A N
Prader-Willi, an example of gene imprinting, is not associated with any autosomal sex-linked abnormality.
4. A patient, age 9, is admitted to a pediatric unit with Duchenne muscular dystrophy. When planning care, the nurse recalls the patient inherited this condition through a trait that is:
a. X-linked dominant.
b. X-influenced.
c. X-limited.
d. X-linked recessive.
ANS: D
Duchenne muscular dystrophy is a relatively common X-linked recessive, not dominant, disorder. While it is sex linked, it is not X-limited or X-influenced.
5. A child is diagnosed with cystic fibrosis. History reveals that the child’s parents are siblings. Cystic fibrosis was most likely the result of:
a. X-inactivation.
b. genomic imprinting.
c. consanguinity.
d. obligate carriers.
ANS: C
Consanguinity refers to the mating of two related individuals, and the offspring of such matings are said to be inbred. Consanguineous matings produce a significant increase in recessive disorders and are seen most often in pedigrees for rare recessive disorders.
X-inactivation occurs when one X chromosome in the somatic cells of females is permanently inactivated. Genomic imprinting is related to methylation and other changes. Obligate carriers are those who have an affected parent and affected children and, therefore, must themselves carry the mutation.
6. A 12-year-old male is diagnosed with Klinefelter syndrome. His karyotype would reveal which of the following?
a. XY
b. XX
c. XYY
d. XXY
ANS: D
A person with Klinefelter syndrome has an XXY karyotype. An XY is a normal male. An XX is a normal female. An XYY is an aneuploid karyotype.
7. To express a polygenic trait:
a. genes must interact with the environment.
b. several genes must act together.
c. multiple mutations must occur in the same family.
d. penetrance must occur.
ANS: B
Polygenic traits are those that result from several genes acting together. When environmental factors influence the expressionNof the trait, the term multifactorial inheritance is used. When
multiple mutations occur in the same family, the mechanism most likely responsible is termed germline mosaicism. Penetrance of a trait is the percentage of individuals with a specific genotype who also exhibit the expected phenotype.
8. What is the diagnosis of a 13-year-old female who has a karyotype that reveals an absent homologous X chromosome with only a single X chromosome present? Her features include a short stature, widely spaced nipples, and a reduced carrying angle at the elbow.
a. Down syndrome
b. Cri du chat syndrome
c. Turner syndrome
d. Klinefelter syndrome
ANS: C
Turner syndrome is characterized by short stature, female genitalia, webbed neck, shield-like chest with underdeveloped breasts and widely spaced nipples, and imperfectly developed ovaries. Down syndrome is characterized by distinctive characteristics: low nasal bridge, epicanthal folds, protruding tongue, and low-set ears. Cri du chat syndrome is characterized by low birth weight, severe mental retardation, microcephaly (smaller than normal head size), and heart defects. Klinefelter syndrome is characterized by small testes, some development of the breasts, sparse body hair, and long limbs.
9. The gradual increase in height among the human population over the past 100 years is an example of:
a. a polygenic trait.
b. a multifactorial trait.
c. crossing over.
d. recombination.
ANS: B
The gradual increase in height is an example of multifactorial traits influenced by genes and also by environment. Polygenic traits result from several genes acting together. Crossing over is an abnormal chromosome structure. Recombination results from new arrangements of alleles.
10. When discussing DNA replication, which enzyme is most important?
a. RNA polymerase
b. Transfer RNA
c. Messenger RNA
d. DNA polymerase
ANS: D
DNA polymerase, not RNA polymerase, is the primary enzyme involved in replication. It adds bases to the new DNA strand and performs “proofreading” functions. Neither messenger RNA nor transfer RNA is as important to DNA replication.
11. The regions of the heterogeneous nuclear RNA that must be spliced out to form functional RNA are called:
a. promoter sites.
b. introns.
c. exons.
d. anticodon. N
ANS: B
When the mRNA is first transcribed from the DNA template, it reflects exactly the base sequence of the DNA. In eukaryotes, many RNA sequences are removed by nuclear enzymes, and the remaining sequences are spliced together to form the functional mRNA that migrates to the cytoplasm. The excised sequences are called introns (intervening sequences), and the sequences that are left to code for proteins are called exons. In translation, RNA directs the synthesis of a polypeptide, a cloverleaf-shaped strand of about 80 nucleotides. The tRNA molecule has a site where an amino acid attaches. The three-nucleotide sequence at the opposite side of the cloverleaf is called the anticodon.
12. A 50-year-old male was recently diagnosed with Huntington disease. Transmission of this disease is associated with:
a. penetrance of a trait.
b. recurrence risk.
c. expressivity.
d. delayed age of onset.
ANS: D
A key feature of Huntington disease is its delayed age of onset such that symptoms are not seen until 40 years of age or later. The penetrance of a trait is the percentage of individuals with a specific genotype who also exhibit the expected phenotype. Recurrence risk is the percentage of family members who will inherit the disease. Expressivity is the extent of variation in phenotype associated with a particular genotype.
13. What type of mutation does not change the amino acid sequence and thus has no observable consequence?
a. Frameshift
b. Spontaneous
c. Silent
d. Missense
ANS: C
Silent mutations do not change the amino acid sequence and therefore have no consequences. Frameshift mutations involve the insertion or deletion of one or more base pairs of the DNA molecule. They alter the amino acid sequence. Spontaneous mutations occur in the absence of exposure to a mutagen and produce changes in the amino acid sequence. Missense mutations, a form of base pair substitution, alter amino acids, which produce a change (i.e., the “sense”) in a single amino acid.
14. A nurse is reviewing the pedigree chart. When checking for a proband, what is the nurse looking for?
a. The person who is first diagnosed with a genetic disease.
b. The individual who has a disease gene but is phenotypically normal.
c. The phenotype of genetic material.
d. The codominance. N
ANS: A
The pedigree chart summarizes family relationships and shows which members of a family are affected by a genetic disease. The pedigree begins with the proband. The person who has a disease gene but is phenotypically normal is a carrier. The phenotype is the result of both genotype and environment; it is not a proband. Codominance is not represented by a proband, but it occurs when the heterozygote is distinguishable from both homozygotes.
15. Which of the following disorders is manifested primarily in males?
a. Cystic fibrosis
b. Neurofibromatosis
c. Muscular dystrophy
d. Klinefelter syndrome
ANS: C
Muscular dystrophy is manifested primarily in males. Cystic fibrosis, neurofibromatosis, and Klinefelter syndrome are manifested in both males and females.
MULTIPLE RESPONSE
1. When the nurse is teaching the staff about X-linked recessive disorders, which information should the nurse include? (Select all that apply.)
a. The trait is seen much more often in females than in males.
b. The trait is never transmitted from father to son.
c. The gene can be transmitted through a series of carrier females.
d. The gene is passed from an affected father to all his daughters.
e. The trait never skips generations.
ANS: B, C, D
The principles of X-linked recessive inheritance include: the trait is seen much more often in males than in females; the trait is never transmitted from father to son; the gene can be transmitted through a series of carrier females; the gene is passed from an affected father to all his daughters, who, as phenotypically normal carriers, transmit it to approximately half their sons, who are affected. X-linked recessive disorders can skip generations since it is a one in four chance.
N
Chapter 03: Epigenetics and Disease
Huether: Understanding Pathophysiology, 7th Edition
MULTIPLE CHOICE
1. When considering abnormal epigenetic modifications, what factor is currently being viewed as strongly associated with the development of some cancers?
a. Family genetics
b. Lifestyle choices
c. Environmental stressors
d. Emotional coping skills
ANS: C
Environmental stressors can markedly increase the risk of aberrant epigenetic modification and are strongly associated with some cancers. While genetics, lifestyle choices, and coping skills can affect the development and management of cancer, they are not currently considered as being the primary factors in the epigenetic modification that occurs.
2. Housekeeping genes are vital to the function and maintenance of all the body’s cells. What characteristic is associated with these genes?
a. They lack encoding histones.
b. They are transcriptionally active.
c. Ribosomal RNA genes are absent.
d. Epigenetic silencing has occurred.
ANS: B
A small percentage of genes, teNrmed housekeeping genes, are necessary for the function and
maintenance of all cells. These genes escape epigenetic silencing and remain transcriptionally active in all or nearly all cells. Housekeeping genes include encoding histones, DNA and RNA polymerases, and ribosomal RNA genes.
3. What characteristic of Prader-Willi syndrome is not a characteristic of Angelman syndrome?
a. It is inherited from the father.
b. Mental retardation is observable.
c. Imprinting of an abnormal chromosome 15.
d. Seizure disorder is present.
ANS: A
A well-known disease example of imprinting is associated with a deletion of about 4 million base (Mb) pairs of the long arm of chromosome 15. When this deletion is inherited from the father, the child manifests Prader-Willi syndrome, whose features include short stature, hypotonia, small hands and feet, obesity, mild to moderate mental retardation, and hypogonadism. The same 4 Mb deletion, when inherited from the mother, causes Angelman syndrome, which is characterized by severe mental retardation, seizures, and an ataxic gait.
4. Research has demonstrated that neural stem cells have an impaired ability to differentiate into functional neurons when subjected to:
a. ethanol.
b. marijuana.
c. insufficient nutrients.
d. poor oxygenation.
ANS: A
It has been found that treating cultured neural stem cells with ethanol impairs their ability to differentiate to functional neurons; this impairment seems to be correlated with aberrant, dense methylation at loci that are active in normal neuronal tissue. The research does not support the effects of marijuana, insufficient nutrition, or poor oxygenation on the stem cell’s ability to differentiate appropriately.
5. What is the role of inactive MLH1 in the development of some forms of inherited colon cancer?
a. Deletion of a nucleotide repeat in the DUX4 gene.
b. DNA damage is left unrepaired.
c. Expansion in the number of cytosine-guanine (CG) dinucleotide.
d. Abnormalities of chromosome 11p15.5 that lead to downregulation of IGF2.
ANS: B
A major cause of one form of inherited colon cancer (hereditary nonpolyposis colorectal cancer [HNPCC]) is the methylation of the promoter region of a gene, MLH1, whose protein product repairs damaged DNA. When MLH1 becomes inactive, DNA damage accumulates, eventually resulting in colon tumors. Fascioscapulohumeral muscular dystrophy (FSHMD) is associated with the DUX4 gene. Fragile X is associated with the cytosine-guanine (CG) dinucleotide. Downregulation of IGF2 is associated with Russell-Silver syndrome.
6. Mutations in the encoding of histone-modifying proteins have been shown to influence the development of what congenial condition?
a. Cleft palate
b. Acephalous N
c. Heart disease
d. Webbed digits
ANS: C
Mutations in genes that encode histone-modifying proteins have been implicated in congenital heart disease. Research has yet to provide a relationship between abnormal histone-modifying proteins and cleft palate, acephalous, and webbed digits.
7. Which embryonic stem cell characteristic is referred to as totipotent?
a. Ability to differentiate into any type of somatic cell.
b. Ability to repair its own damaged DNA.
c. Ability to determine which parental chromosome copy it will imprint.
d. Ability to minimize the impact of poor in utero nutrition.
ANS: A
Each of the cells in the very early embryo has the potential to give rise to a somatic cell of any type. These embryonic stem cells are therefore said to be totipotent (“possessing all powers”). The term totipotent does not infer the ability to repair damaged DNA, select specific chromosome copies, or adjust for poor in utero nutrition.
8. 5-Azacytidine has demonstrated promise in the treatment of which form of cancer?
a. Liver
b. Colon
c. Gallbladder
d. Pancreatic
ANS: D
Though associated with various side effects, including digestive disturbance, 5-azacytidine has shown promise in the treatment of pancreatic cancer. There is no support for its use in the treatment of liver, colon, or gallbladder cancers.
9. During which stage of human development does the role of epigenetics have the greatest impact on the development of epigenetic abnormalities?
a. Infancy
b. Puberty
c. In utero
d. Middle age
ANS: C
Conditions encountered in utero, during childhood, and even during adolescence or later can have long-term impacts on epigenetic states, which sometimes can be transmitted across generations. The impact is not supported for the periods of infancy, puberty, and middle age.
10. What comorbid condition does an individual diagnosed with Beckwith-Wiedemann syndrome have an increased risk of developing?
a. Cancer
b. Diabetes
c. Depression
d. Food allergies
ANS: A N
Beckwith-Wiedemann syndrome is accompanied by an increased predisposition to cancer. There is no current correlation between Beckwith-Wiedemann syndrome and diabetes, depression, or food allergies.
MULTIPLE RESPONSE
1. Screening tools that are epigenetically based have shown promise in diagnosing which types of cancer? (Select all that apply.)
a. Colon
b. Breast
c. Skin
d. Bladder
e. Prostate
ANS: A, B, D, E
Monitoring for misregulation of miRNAs has shown promise as a tool for early diagnosis of cancers of the colon, breast, and prostate. Other epigenetics-based screening approaches have shown promise for detection of cancers of the bladder, lung, and prostate. Such screenings have not yet been developed for skin cancers.
2. Research has provided support for the theory that epigenetic modifications can result from deficient in utero nutrition causing which chronic disease? (Select all that apply.)
a. Obesity
b. Asthma
c. Cardiovascular disease
d. Diabetes
e. Crohn’s disease
ANS: A, C, D
When researchers sought to investigate how exposure to famine in utero had impacted individuals born in a historically prosperous country whose nutritional intake was dramatically impacted by WWII, they found that individuals who suffered nutritional deprivation in utero were more likely to suffer from obesity and diabetes as adults than individuals who had not experienced nutritional deprivation during gestation. Other data sets reveal elevated risk of cardiovascular and metabolic disease for offspring of individuals exposed during early development to fluctuations in agricultural yields. The research does support the development of asthma or Crohn’s disease.
N
Chapter 04: Altered Cellular and Tissue Biology Huether: Understanding Pathophysiology, 7th Edition
MULTIPLE CHOICE
1. A report comes back indicating that muscular atrophy has occurred. A nurse recalls that muscular atrophy involves a decrease in muscle cell:
a. number.
b. size.
c. vacuoles.
d. lipofuscin.
ANS: B
Atrophy is a decrease or shrinkage in cellular size. Hyperplasia is an increase in the number of cells. Vacuoles are membrane-bound vesicles within the cell that contain cellular debris and hydrolytic enzymes. Lipofuscin is the yellow-brown age pigment.
2. During childhood, the thymus decreases in size, and this is referred to as what type of atrophy?
a. Physiologic
b. Pathologic
c. Disuse
d. Neurogenic
ANS: A
A normal decrease in cell size is physiologic atrophy. Atrophy can result from disease (pathologic), disuse, or nerve inNjury (neurogenic).
3. When planning care for a cardiac patient, the nurse knows that in response to an increased workload, cardiac myocardial cells will experience hypertrophy which is an:
a. increase in size.
b. decrease in length.
c. increase in excitability.
d. decrease in number.
ANS: A
Hypertrophy is a compensatory increase in the size of cells in response to mechanical stimuli (also called mechanical load or stress, such as from stretching, repetitive, chronic, pressure, or volume overload) and consequently increases the size of the affected organ. The cells of the heart and kidneys are particularly prone to enlargement. A decrease in length is not associated with hypertrophy. A deficiency of electrolytes or minerals could lead to an increase in excitability; it is not due to increased workload or related to hypertrophy. A decrease in cell numbers is referred to as hypoplasia.
4. A 55-year-old male with a 30-year history of smoking is examined for respiratory disturbance. Examination of his airway (bronchial) reveals that stratified squamous epithelial cells have replaced the normal columnar ciliated cells. This type of cellular adaptation is called:
a. anaplasia.
b. hyperplasia.
c. metaplasia.
d. dysplasia. [Show Less]