Xeroderma pigmentosa (XP): A. is caused by a defect in the mismatch repair system. B. typically results in base substitution mutations. C. can be caused by defects in any of a number of different genes that have to do with DNA repair. D. results when an individual does not spend enough time outside. E. Can be corrected by a direct repair mechanism

Xeroderma pigmentosa (XP): A. is caused by a defect in the mismatch repair system. B. typically results in base substitution mutations. C. can be caused by defects in any of a number of different genes that have to do with DNA repair. D. results when an individual does not spend enough time outside. E. Can be corrected by a direct repair mechanism

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter11: Genome Alterations: Mutation And Epigenetics

Section: Chapter Questions

Problem 19QP: Our bodies are not defenseless against mutagens that alter our genomic DNA sequences. What...

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The experiment below is from a seminal set of experiments in the 1960s that illustrated the role of various repair pathways for DNA damage caused by UV radiation. In this experiment, the scientists isolated E coli strains that are mutant in the Rec A gene, the UvrA gene or both. They then irradiated cultures of each strain with increasing doses of UV light and measured the effect on cell viability. Answer the following questions about this data. A. Which DNA repair pathway and repair activity is inhibited by the Rec A mutant? B. Which DNA repair pathway and repair function is inhibited by UvrA mutant? C. Why is the UvrA/RecA double mutant so much more senitive to UV light than either mutant alone?
Which of the following is true of reverse transcriptase?a. It is required for the movement of DNA transposons.b. It catalyzes the synthesis of DNA from RNA.c. It is required for the transposition of retrotransposons.d. b and c are correct.
You are an expert in DNA-repair mechanisms. You receive a sample of a human cell line derived from a woman who has symptoms of xeroderma pigmentosum. You determine that she has a mutation in a gene that has not been previously associated with XP. How is this possible?
In general, all mutations can be considered harmful, because most genetic systems are already optimized to work correctly and efficiently. A. True b. False; mutations are considered harmful only if they have a direct effect on the ability of cells to synthesize DNA c. False; some mutations are harmful, and some are considered beneficial
The figure below summarizes the results of an experiment evaluating the role of Ku80 gene DNA repair. The Ku80 Knock Out mice were generated by genetically deleting the Ku80 gene and the effects of ionizing radiation on lifespan were evaluated. Briefly explain why Ku80 deletion has the observed effects. What form of DNA damage is causing the reduced lifespan and which repair mechanism appears to be responsible for repair of these lesion in normal mice?
During X inactivation, all but one gene get silenced on one X chromosome. Why does one gene escape the inactivation? A) That is the gene responsible for inactivating the others B) Two copies of that gene are needed in females, so both are active C) X inactivation is rarely complete, so occasionally one or two genes get activated by mistake D) That is the gene that encodes the methyltransferase needed to methylate the genome.
Give at least 3 ways an organism can counteract DNA damage and mutations by activating several types of repair systems and give example of type.
The BRCA genes produce DNA repair proteins. Genetic testing is available that can determine if a person has a mutation in the BRCA genes that makes the proteins less able to function. What is the result of a BRCA mutation? A. The person is more likely to develop cancer if other DNA in the cell mutates. B. The person is less likely to develop cancer unless the BRCA region is methylated. C. The person is less likely to develop cancer because the BRCA gene will inhibit the cell cycle checkpoints. D. The person is more likely to develop cancer because the BRCA gene promotes an increased rate for mitosis.
What is an advantage and a disadvantage of this repair system?
Explain how nucleotide incorporation errors by DNA polymerase can be repaired, and the role of methylation in the process.
A biology professor at a prestigious university stated to his introductory class that "Today, a basic understanding of DNA and genetics is as important as a basic understanding of computers and the internet."Based upon what you have learned about DNA and gene expression in this module, how could you make a case to support this statement?
Which, if any, of the following statements is false? a) Most of the inherited changes in our DNA arise because of exposure to extracellular mutagens, including radiation sources and chemical mutagens. b) Most of the inherited changes in our DNA arise because of unavoidable endogenous errors in cellular mechanisms and harmful effects of certain natural molecules and atoms within our cells. c) Errors in DNA replication and DNA repair are a major source of mutations in our cells. d) Significant chemical damage is sustained by DNA because of its proximity to water molecules in our cells.