Complete Test Bank With Answers
Sample Questions Posted Below
| 1. |
When explaining genetic coding to a group of students, the instructor discusses gene activation and deactivation. It was stressed that inactivation of a gene requires which of the following processes? |
| A) |
Methylation of histone amino acid |
| B) |
Acetylation of histone amino acid |
| C) |
Release of endonucleases |
| D) |
Protein-synthesizing apparatus of mitochondrial DNA |
| Ans: |
A |
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Feedback: |
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Although solving the structural problem of how to fit a huge amount of DNA into the nucleus, the chromatin fiber, when complexed with histones and packaged into various levels of compaction, makes the DNA inaccessible during the processes of replication and gene expression. Several chemical interactions are now known to affect this process. One of these involves the acetylation of a histone amino acid group that is linked to opening of the chromatin fiber and gene activation. Another important chemical modification involves the methylation of histone amino acids, which is correlated with gene inactivation. Several repair mechanisms exist, and each depends on specific enzymes called endonucleases that recognize distortions of the DNA helix, cleave the abnormal chain, and remove the distorted region. Replication of mtDNA depends on enzymes encoded by nuclear DNA. Thus, the protein-synthesizing apparatus and molecular components for oxidative metabolism are jointly derived from nuclear and mitochondrial genes. |
| 2. |
When an infant is born with gene mutations in his cells, the nurse explains to the parents that accidental errors may be a result of: Select all that apply. |
| A) |
Loss of one or more base pairs |
| B) |
Substitution of one base pair for another |
| C) |
Induction of chromatin to change its structure |
| D) |
Rearrangement of the base pairs |
| Ans: |
A, B, D |
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Feedback: |
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Genetic mutations occur in germ cells (inherited errors) or somatic cells. Germ cell mutations can be spontaneous or an error of base pair deletion, substitution of one pair for a different pair, or rearrangement of the sequence of base pairs. Somatic cell mutations affect a cell line that differentiates into tissue types. Although solving the structural problem of how to fit a huge amount of DNA into the nucleus, the chromatin fiber, when complexed with histones and packaged into various levels of compaction, makes the DNA inaccessible during the processes of replication and gene expression. To accommodate these processes, chromatin must be induced to change its structure, a process called chromatin remodeling. |
| 3. |
Which of the following statements is true of genetic mutations? |
| A) |
Errors in DNA duplication are normally irreparable. |
| B) |
Mutations that occur in somatic cells are inheritable. |
| C) |
Mutations may result from environmental agents. |
| D) |
Errors in DNA replication are most often fatal. |
| Ans: |
C |
|
Feedback: |
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In addition to random errors, extrinsic factors such as environmental agents, chemicals, and radiation can induce errors in DNA duplication. DNA repair mechanisms resolve the majority of mutations. As a result, most mutations are corrected and do not result in pathology or death. Only those DNA changes that occur in germ cells can be inherited. |
| 4. |
While explaining the individual differences in physical traits in the family group, the health care provider states this is usually a result of: |
| A) |
An enzyme interfering with DNA sequence |
| B) |
An environmental chemical exposure |
| C) |
Small DNA sequence variation |
| D) |
Ischemia within the cell wall |
| Ans: |
C |
|
Feedback: |
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It is the small DNA sequence variation (1 in every 1000 base pairs) that is thought to account for the individual differences in physical traits, behaviors, and disease susceptibility. Enzyme interference, chemical exposure, and ischemia are not believed to be responsible for these differences. |
| 5. |
Which genetic disorders (body system) have a high requirement for oxidative metabolism associated with mitochondrial DNA? |
| A) |
Cardiac dysrhythmias |
| B) |
Neuromuscular disorders |
| C) |
Renal abnormalities |
| D) |
Facial deformities |
| Ans: |
B |
|
Feedback: |
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In addition to nuclear DNA, part of the DNA of a cell resides in the mitochondria. Mitochondrial DNA (mtDNA) is inherited from the mother by her offspring. Genetic disorders of mitochondrial DNA commonly affect tissues such as those of the neuromuscular system that have a high requirement for oxidative metabolism. |
| 6. |
Which of the following statements is true of messenger RNA (mRNA)? |
| A) |
mRNA is produced in the nucleolus. |
| B) |
mRNA provides the template for protein synthesis. |
| C) |
Each mRNA molecule has two recognition sites. |
| D) |
mRNA delivers the activated form of an amino acid to the protein being synthesized. |
| Ans: |
B |
|
Feedback: |
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mRNA is a long molecule containing several hundred to several thousand nucleotides and is the template for the process of protein synthesis. rRNA, not mRNA, is produced in the nucleolus, whereas tRNA has two specific recognition sites and delivers an activated form of an amino acid to a protein being synthesized. |
| 7. |
When comparing and contrasting the various forms of RNA, the pathophysiology instructor identifies that ribosomal RNA (rRNA) is unique in that it: |
| A) |
Is produced in the nucleolus |
| B) |
Delivers activated amino acids |
| C) |
Is formed by transcription |
| D) |
Coordinates RNA translation |
| Ans: |
A |
|
Feedback: |
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Ribosomal RNA (rRNA) is produced in the nucleolus and combines with ribosomal proteins in the nucleus to produce the ribosome. Transfer RNA (tRNA) delivers the activated form of amino acids to protein molecules in the ribosome. Messenger RNA (mRNA) is formed by the transcription process. Translation (protein synthesis) requires the coordinated actions of mRNA, tRNA, and rRNA. |
| 8. |
A physiology instructor asks the students about the purpose of the promoter region on a DNA strand. Which student response is most accurate? |
| A) |
Contains amino acids that the RNA polymerase recognized and binds to, thus starting the replication process |
| B) |
Location for protein-coding regions of the mRNA sequences |
| C) |
Delivers activated amino acids to begin mitosis |
| D) |
Reverses redundant base pairs |
| Ans: |
A |
|
Feedback: |
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During transcription, RNA polymerase recognizes the start sequence of a gene and attaches to the DNA. It is initiated by the assembly of a transcription complex composed of RNA polymerase and other associated factors. This complex binds to the double-stranded DNA at a specific site called the promoter region. Within the promoter region is the so-called “TATA box,” which contains the crucial thymine–adenine–thymine–adenine sequence that RNA polymerase recognizes and binds to, starting the replication process. Exons are RNA sequences retained on the original RNA during splicing. tRNA delivers activated amino acids to proteins in the ribosome. When several triplet codons encode the same amino acid, the genetic code is said to be redundant. |
| 9. |
Splicing of mRNA during processing permits a cell to: |
| A) |
Form different proteins |
| B) |
Increase DNA content |
| C) |
Stop copying DNA onto RNA |
| D) |
Add nucleic acid end pieces |
| Ans: |
A |
|
Feedback: |
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Splicing permits a cell to produce a variety of mRNA molecules from a single gene, thus reducing how much DNA must be contained in the genome. Stop codes signal the end of a protein molecule, and RNA strands are then processed. Processing involves addition of certain nucleic acids to the RNA; splicing involves removing segments of RNA. |
| 10. |
A genetic test result returns noting that the specimen (client) has inclusion bodies in the sample. The health care provider can associate this result with the development of which pathologic disease process? Select all that apply. |
| A) |
Alzheimer disease |
| B) |
Parkinson disease |
| C) |
Myasthenia gravis |
| D) |
Multiple myeloma |
| Ans: |
A, B |
|
Feedback: |
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Disruption of chaperoning mechanisms causes intracellular molecules to become denatured and insoluble. These denatured proteins tend to stick to one another, precipitate, and form inclusion bodies. The development of inclusion bodies is a common pathologic process in Parkinson, Alzheimer, and Huntington diseases. |
| 11. |
Which of the following would be an example of gene expression? Select all that apply. |
| A) |
Control of insulin expression so it gives a signal for blood glucose regulation |
| B) |
Induction by an external influence to facilitate having a male child |
| C) |
Increasing the amount of UV light exposure to end up with darker skin |
| D) |
Activation of growth control genes by injecting growth hormone into a small for age male child |
| Ans: |
A, C |
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Feedback: |
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The degree to which a gene or particular group of genes is active is called gene expression. A phenomenon termed induction is an important process by which gene expression is increased. Gene repression is a process by which a regulatory gene acts to reduce or prevent gene expression. Activator and repressor sites commonly monitor levels of the synthesized product and regulate gene transcription through a negative feedback mechanism. Whenever product levels decrease, gene transcription is increased, and when product levels increase, gene transcription is repressed. Control of insulin expression so it gives a signal for blood glucose regulation and increases the amount of UV light exposure to end up with darker skin are examples of the negative feedback system. |
| 12. |
Identifying the genetic sex of a child is based on finding intracellular Barr bodies that consist of: |
| A) |
Inactive chromatin material |
| B) |
Male-specific chromosomes |
| C) |
Homologous chromosomes |
| D) |
Excess autosomal material |
| Ans: |
A |
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Feedback: |
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Barr bodies are present only when there is more than one X in each cell, signifying a female. The extra X is inactivated and stored as chromatin material that can be visualized in epithelial cells. Genetically normal males have one X and one Y chromosome, so a Barr body is not present. Male-specific encoding is on the Y chromosome only. The maternal and paternal chromosomes of a pair are called homologous chromosomes (homologs). |
| 13. |
Prenatal genetic testing that counts the number of Barr bodies in a chromosome is able to determine: |
| A) |
The genetic sex of a child |
| B) |
Susceptibility to hemophilia B |
| C) |
The presence of fragile X syndrome |
| D) |
Fetal viability |
| Ans: |
A |
|
Feedback: |
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The genetic sex of a child can be determined by microscopic study of cell or tissue samples because the total number of X chromosomes (which determine sex) is equal to the number of Barr bodies plus one. Genetic testing can reveal the presence of inherited disorders such as fragile X syndrome and hemophilia, but the focus of such testing is not the Barr bodies. Similarly, overall fetal viability is not ascertained from identifying Barr bodies. |
| 14. |
Crossing-over of chromatid segments during meiosis division 1 results in: |
| A) |
Spontaneous gene mutations |
| B) |
Initial DNA synthesis |
| C) |
Bivalent X and Y genes |
| D) |
New gene combinations |
| Ans: |
D |
|
Feedback: |
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Crossing-over of chromatid segments allows for new gene combinations and increased genetic variability. It is unrelated to mutations. DNA synthesis occurs only during or after meiosis division 2. Because X and Y chromosomes are not homologs, they do not pair up to form bivalents during meiosis division 1. |
| 15. |
When discussing upcoming chromosome studies, a client asks, “What kind of sample are they going to take to do these tests?” The nurse replies, “The most common cells used for this purpose are: |
| A) |
From lymph nodes from your underarm.” |
| B) |
Lymphocytes from a venous blood specimen.” |
| C) |
Skin scrapings from your back.” |
| D) |
From a bone marrow biopsy.” |
| Ans: |
B |
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Feedback: |
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Chromosome studies can be done on any tissue or cell that grows and divides in culture. Lymphocytes from venous blood are frequently used for this purpose. |
| 16. |
While lecturing on inheritance patterns, a student asks, “My mother has blue eyes and my father has brown eyes. All my siblings have brown eyes except me. How can this happen?” Which of the following is the most accurate response? |
| A) |
Phenotypically, the brown-eyed persons are the same, but genotypically they are different. |
| B) |
This is known as penetrance, where a gene has its ability to express its function. |
| C) |
Expressivity is when a gene is expressed in the phenotype. |
| D) |
Blue sclera is a genetic mutation. |
| Ans: |
A |
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Feedback: |
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More than one genotype may have the same phenotype. Some brown-eyed persons carry one copy of the gene that codes for blue eyes, and other brown-eyed persons do not. Phenotypically, these two types of brown-eyed persons are the same, but genotypically they are different. Expressivity refers to the manner in which the gene is expressed in the phenotype, which can range from mild to severe. Penetrance represents the ability of a gene to express its function. Seventy-five percent penetrance means 75% of persons of a particular genotype present with a recognizable phenotype. Blue sclera is a genetic mutation but not relative in this example. |
| 17. |
The gene responsible for a particular congenital cardiac anomaly is said to have complete penetrance. What are the clinical implications of this fact? |
| A) |
The anomaly is a result of polygenetic inheritance. |
| B) |
The heart defect does not result from any other gene. |
| C) |
Multiple alleles contribute to the defect. |
| D) |
All the individuals who possess the gene will exhibit the anomaly. |
| Ans: |
D |
|
Feedback: |
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Penetrance represents the ability of a gene to express its function, with complete, or 100%, penetrance, ensuring that all individuals possessing the gene will experience the phenotype in question. The disorder is not necessarily the result of multiple alleles or polygenetic inheritance, and complete penetrance does not mean that the disorder is a single-gene trait. |
| 18. |
A pregnant female has been told she is a carrier for fragile X syndrome. She asks, “What does that mean?” The health care provider explains that she is heterozygous for fragile X recessive trait, but this will only be a problem if: |
| A) |
The expressed pairing becomes homozygous. |
| B) |
The expressed pairing switches to a dominant trait. |
| C) |
Her mate also is a carrier of the recessive fragile X trait. |
| D) |
She does not receive a blood transfusion from a non–fragile X donor prior to pregnancy. |
| Ans: |
A |
|
Feedback: |
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Offspring in whom the two alleles of a given pair are the same are called homozygotes. For example, a plant may have two alleles for wrinkled peas. Heterozygotes have different alleles at a gene locus. All offspring with a dominant allele manifest that trait. In human genetics, a carrier is a person who is heterozygous for a recessive trait and does not manifest the trait. For example, the gene for the genetic disorder cystic fibrosis is recessive. Therefore, only persons with a genotype having two alleles for cystic fibrosis have the disease. In most cases, neither parent manifests the disease; however, both must be carriers. A blood transfusion will not fix the problem. |
| 19. |
A child with cystic fibrosis (CF) asks the nurse why he has this disease, but his parents are perfectly healthy. The nurse explains: |
| A) |
Environmental conditions affect on alleles and therefore who get CF |
| B) |
Both parents are carriers and have a recessive genotype with alleles for CF. |
| C) |
One of your parents may have a mild recessive form of CF. |
| D) |
Both parents have homozygous pairing of two alleles for CF. |
| Ans: |
B |
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Feedback: |
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Both multifactorial inheritance and polygenic inheritance involve multiple genes at different loci. Multifactorial is different because it involves the effects of the environment on genes also. Unlike Mendel law, multifactorial inheritance and polygenic inheritance are unpredictable. Homozygous pairing of alleles is characteristic of recessive traits. The gene for the genetic disorder cystic fibrosis is recessive. Therefore, only persons with a genotype having two alleles for cystic fibrosis have the disease. In most cases, neither parent manifests the disease; however, both must be carriers. |
| 20. |
When discussing linkage studies, the instructor mentions that colorblindness is found in a small section of the X chromosome and has been linked to development of which of the following diseases? Select all that apply. |
| A) |
Early-onset Alzheimer disease |
| B) |
Hemophilia A |
| C) |
Adrenal hyperplasia |
| D) |
Down syndrome |
| Ans: |
B, C |
|
Feedback: |
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When two inherited traits occur together at a rate greater than would occur by chance alone, they are said to be linked. Color blindness has been linked to classic hemophilia A (i.e., lack of factor VIII) in some pedigrees; hemophilia A has been linked to glucose-6-phosphate dehydrogenase deficiency in others; and color blindness has been linked to glucose-6-phosphate dehydrogenase deficiency in still others. Because the gene for color blindness is found on the X chromosome, all three genes must be found in a small section of the X chromosome. Alzheimer disease and Down syndrome have not been associated with a linkage disorder. |
| 21. |
A client diagnosed with a cancer has been prescribed monoclonal antibodies as a treatment option. He asks the health care provider, “What are you talking about? I’ve never heard of this treatment. Is it experimental?” The health care provider explains somatic cell hybridization to the client by explaining that: |
| A) |
Researchers inject mice with an antigen from human cancer cells. They then harvest the antibody-producing cells from the mice and individually fuse them with a cancerous cell. |
| B) |
Short sequences of base pairs can be synthesized, radioactively labeled, and subsequently used to identify their complementary sequence. |
| C) |
The DNA molecule is cut apart using a bacterial enzyme, called a restriction enzyme, that binds to DNA wherever a particular short sequence of base pairs is found and cleaves the molecule at a specific nucleotide site. |
| D) |
The restrictive fragments of DNA can often be replicated through insertion into a unicellular organism, such as a bacterium. |
| Ans: |
A |
|
Feedback: |
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Somatic cell hybridization involves the fusion of human somatic cells with those of a different species (typically, the mouse) to yield a cell containing the chromosomes of both species. Because these hybrid cells are unstable, they begin to lose chromosomes of both species during subsequent cell divisions. In situ hybridization involves the use of specific sequences of DNA or RNA to locate genes that do not express themselves in cell culture. DNA and RNA can be chemically tagged with radioactive or fluorescent markers. Gene mapping that is performed using dosage studies involves measuring enzyme activity. The restrictive fragments of DNA can often be replicated through insertion into a unicellular organism, such as a bacterium. In cloning, the restrictive fragments of DNA can often be replicated through insertion into a unicellular organism, such as a bacterium. |
| 22. |
From the following list, which medications have been developed utilizing recombinant DNA technology? Select all that apply. |
| A) |
Insulin, for clients with diabetes |
| B) |
Coumadin, a blood thinner for irregular heartbeats |
| C) |
Erythropoietin to help the body generate more RBCs |
| D) |
Tissue plasminogen activator (tPA) to dissolve a clot in the brain |
| E) |
Zyrtec, for allergies |
| Ans: |
A, C, D |
|
Feedback: |
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Recombinant DNA technology has also made it possible to produce proteins that have therapeutic properties. One of the first products to be produced was human insulin. More complex proteins are produced in mammalian cell culture using recombinant DNA techniques. These include erythropoietin, which is used to stimulate red blood cell production; factor VIII, which is used to treat hemophilia; and tissue plasminogen activator (tPA), which is frequently administered after a heart attack to dissolve the thrombi that are obstructing coronary blood flow. Coumadin and Zyrtec are not manufactured using recombinant DNA technology. |
| 23. |
When a client with a kidney transplant develops graft versus host disease, a suicide gene transfer can be accomplished by: |
| A) |
Giving a blood transfusion from the donor |
| B) |
Infusion of donor lymphocytes |
| C) |
Increasing the dose of corticosteroids |
| D) |
Administering radioactive tracer cells |
| Ans: |
B |
|
Feedback: |
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To date, gene therapy has been used successfully to treat children with severe combined immunodeficiency disease and in a suicide gene transfer to facilitate treatment of graft versus host disease after donor lymphocyte infusion. One of the main approaches to gene therapy is the transferring of genes to replace or selectively inhibit defective ones. Giving a blood transfusion, increasing the steroid dose, or administering a radioactive tracer will assist in the treatment of graft versus host disease. |
| 24. |
Which of the following facts underlies the application of RNA interference in the treatment of disease? |
| A) |
Restriction enzymes are able to cleave genetic molecules at predictable sites. |
| B) |
It is possible to produce proteins that have therapeutic properties. |
| C) |
Faulty gene activity that produces unwanted proteins can sometimes be stopped. |
| D) |
Individual differences are attributable to a very small percentage of the genes in the human body. |
| Ans: |
C |
|
Feedback: |
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RNAi is premised on the fact that several genetic disorders are not due to missing genes, but due to faulty gene activity. RNAi can sometimes be used to stop genes from making unwanted disease proteins. Restriction enzymes underlie gene isolation and cloning. The existence of a haplotype and the ability to produce therapeutic proteins are not central to RNAi. |
| 25. |
Which of the following is an application of recombinant DNA technology? |
| A) |
Production of human insulin |
| B) |
DNA fingerprinting |
| C) |
Gene dosage studies |
| D) |
Somatic cell hybridization |
| Ans: |
A |
|
Feedback: |
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Recombinant DNA technology can be used to direct cells to produce proteins they would not otherwise produce, such as human insulin. DNA fingerprinting does not utilize recombinant DNA technology, whereas gene dosage studies and somatic cell hybridization are genetic mapping methods. |
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