Copyright © 2019, Elsevier Inc. All Rights Reserved. 1Chapter 04: Genes and Genetic DiseasesMcCance/Huether: Pathophysiology: The Biologic Basis of Disease in Adults and Children, 8th EditionMULTIPLE CHOICE 1. In somatic cell gene therapy, what type of vector is most commonly used to alter a specific set of an individual’s somatic cells?a. Virusb. Bacteriac. RNA polymerased. Recombinant DNAANS: AIn somatic cell gene therapy, a vector is used to carry a normal copy of the mutated gene into the individual’s cells. These vectors are usually viruses, such as retroviruses, lentiviruses, or adenoviruses, which have been genetically modified so that they contain the normal human gene and cannot make copies of themselves (otherwise they could cause a viral infection). Bacteria, RNA polymerase, and recombinant DNA are not used as vectors in somatic cell gene therapy.PTS: 1 DIF: Cognitive Level: Remembering 2. In DNA replication, what does the enzyme DNA polymerase do?a. Travel along the single DNA strand, adding the correct nucleotide to the new strandb. Move along the double strand of DNA to unwind the nucleotides of the double helixc. Hold the double strand apart while the correct nucleotides are added to the strandd. Transport the double strand of DNA from the nucleus to the cytoplasm for protein formationANS: AThe DNA polymerase enzyme travels along the single DNA strand, adding the correct nucleotides to the free end of the new strand (see Figure 4-3, B). The correct option is the only one that accurately describes the process involved in DNA replication using DNA polymerase.PTS: 1 DIF: Cognitive Level: Remembering 3. How is transcription best defined?a. DNA polymerase binds to the promoter site on ribonucleic acid (RNA).b. RNA directs the synthesis of polypeptides for protein synthesis.c. RNA is synthesized from a DNA template.d. A base pair substitution results in a mutation of the amino acid sequence.ANS: CTranscription is the process by which RNA is synthesized from a DNA template. The correct option is the only one that accurately defines the term transcription.PTS: 1 DIF: Cognitive Level: Remembering 4. What is the purpose of using a Giemsa staining technique on chromosomes?a. Permit the mitotic process to be followed and monitored for variations.b. Allow for the numbering of chromosomes and the identification of variations.c. Identify new somatic cells formed through mitosis and cytokinesis.d. Distinguish the sex chromosomes from the homologous chromosomes.ANS: BOne of the most commonly used stains is Giemsa stain. By using banding techniques, chromosomes can be unambiguously numbered, and individual variation in chromosome composition can be studied. Missing or duplicated portions of chromosomes, which often result in serious diseases, also can be readily identified. The correct option is the only one that accurately describes the purpose of the Giemsa staining technique.PTS: 1 DIF: Cognitive Level: Remembering 5. An amniocentesis indicates a neural tube defect when an increase in which protein is evident?a. Cytochrome P-450b. Alpha fetoproteinc. DNA polymerased. Embryonic proteinsANS: BOther disorders can be detected with this procedure. These include most neural tube defects, which cause an elevation of alpha fetoprotein in the amniotic fluid, and hundreds of diseases caused by mutations of single genes. Cytochrome P-450 is useful in helping to formulate drug doses more precisely. DNA polymerase travels along the single DNA strand, adding the correct nucleotides to the free end of the new strand during DNA replication. Embryonic proteins are not involved in neural tube defects.PTS: 1 DIF: Cognitive Level: RememberingCopyright © 2019, Elsevier Inc. All Rights Reserved. 2 6. Amniocentesis is recommended for pregnant with what history?a. Have a history of chronic illnessb. Have a family history of genetic disordersc. Have experienced in vitro fertilizationd. Had a late menarcheANS: BAmniocentesis is recommended only for pregnancies known to have an elevated risk for a genetic disease or in women older than 30 to 35 years of age because of the slightly higher risk of fetal loss as compared to the general population. Having a chronic illness, previous in vitro fertilization, or late menarche are not reasons to have an amniocentesis.PTS: 1 DIF: Cognitive Level: Remembering 7. What is the technique for prenatal diagnosis of chromosomal abnormalities at 10 to 12 weeks’ gestation?a. Gene mappingb. Linkage analysisc. Amniocentesisd. Chorionic villus samplingANS: DChorionic villus sampling consists of extracting a small amount of villous tissue directly from the chorion. This procedure can be performed at 10 weeks’ gestation and does not require in vitro culturing of cells; sufficient numbers are directly available in the extracted tissue. Thus the procedure allows prenatal diagnosis at approximately 3 months’ gestation rather than at nearly 4 months’ gestation which is generally when amniocentesis is performed. Gene mapping and linkage analysis are not performed exclusively on women who are 10 weeks’ pregnant.PTS: 1 DIF: Cognitive Level: Remembering 8. What is the term for an error in which homologous chromosomes fail to separate during meiosis or mitosis?a. Aneuploidyb. Nondisjunctionc. Polyploidyd. TranslocationANS: BAneuploidy is usually the result of nondisjunction, an error in which homologous chromosomes or sister chromatids fail to separate normally during meiosis or mitosis. Aneuploidy refers to cells that do not contain a multiple of 23 chromosomes. Polyploidy is when a cell has more than the diploid number of chromosomes, it is said to be a polyploid cell. Translocation refers the interchanging of genetic material between nonhomologous chromosomes.PTS: 1 DIF: Cognitive Level: Remembering 9. A healthcare professional is assessing a child who has complete trisomy of the twenty-first chromosome. What findings does the professional relate to this condition?a. Widely spaced nipples, reduced carrying angle at the elbow, and sparse body hairb. An IQ of 25 to 70, low nasal bridge, protruding tongue, and flat, low-set earsc. High-pitched voice, tall stature, gynecomastia, and an IQ of 60 to 90d. Circumoral cyanosis, edema of the feet, short stature, and mental slownessANS: BThis child has Trisomy 21, also known as Down syndrome. These children typically present with IQs ranging from 25 to 70. The facial appearance is distinctive and
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