Hartwell Genetics Ch. 13 Study Guide

Chapter 13chromosomal Rearrangements and Changes in Chromosome Number Reshape Eukaryote Genomes learn in the Blank 1. Events that reshape genomes by reorganizing the deoxyribonucleic acid sequences inside ane or more chromosomes argon cognise as ____________________. autonomic nervous system rearrangements clog2 2. ____________________, duplications, upendings, translocations, and movements of transpos commensurate elements atomic subprogram 18 severally(prenominal) signs of rearrangements of chromosomal tangible. autonomic nervous system Deletions encumbrance2 3. Very large cut of meats ar visible at the relatively low response of a __________________, showing up as the loss of unmatchable or more bands from a chromosome. autonomic nervous system karyotype trouble2 4. Changes in gene ____________________, the f solely of times a given gene is break in the cell nucleus, shtup create a transmittable imbalance. autonomic nervous system dos get a long with difficulty3 5. An unpaired bulge of one member of a homologous pair of chromosomes during prophase of meiosis I is jockeyn as a ____________________. autonomic nervous system track loop barrier3 6. A recessive variety in the mo give that prevents homozygous animals from walking in a straight line is known as the ____________________ gene. autonomic nervous system shaker-1 worry3 7. When repeats of a region lie adjacent to each other they be called ____________________ duplications. autonomic nervous system tandem bar2 8. Inversions that include the centromere are termed ____________________. Ans pericentric impediment2 9. Inversions that exclude the centromere are termed ____________________. Ans paracentric Difficulty2 10. A hybridization product that lacks a centromere is known as a(n) ____________________fragment. Ans acentric Difficulty2 11. The type of large-scale edition in which unwraps of 2 different chromosomes trad e places is a ____________________ translocation. Ans reciprocal Difficulty2 12. ____________________ is the enzyme that catalyzes transposition. Ans Transposase Difficulty2 13. Organisms with four copies of a particular chromosome (2n+2) are ________________. Ans tetrasomic Difficulty3 14. mint syndrome is also known as ____________________. Ans trisomy 21 Difficulty2 15. If a tetraploid derives all of its chromosome bushels from the same species, we call this kind of polyploid a(n) ____________________. Ans autopolyploid Difficulty3 Multiple Choice 16. Which of the avocation are considered chromosomal rearrangements? A) inversions B) duplications C) deletions D) translocations E) all of the in a gamyer place AnsE Difficulty1 17. Which of the pursuit removes sensible from the genome? A) inversions B) duplications C) deletions D) translocations E) none of the above AnsC Difficulty1 18. Which of the pastime adds material to th e genome? A) inversions B) duplications C) deletions D) translocations E) none of the above AnsB Difficulty1 19. The type of chromosomal rearrangement which reorganizes the DNA sequence at heart one chromosome is known as a(n) A) inversion B) duplication C) deletion D) translocation E) none of the above AnsA Difficulty2 20. In general, which of the undermentioned usually has a greater chance of fatality than the others? A) inversion B) duplication C) deletion D) translocation E) all see an equal chance AnsC Difficulty2 21. Sometimes a piece of one chromosome attaches to some other chromosome.This is known as a(n) A) inversion B) duplication C) deletion D) translocation E) none of the above AnsD Difficulty1 22. Sometimes a part of the genome moves from chromosome to chromosome.This is known generally as a(n) A) inversion B) duplication C) deletion D) translocation E) permutable element AnsE Difficulty2 23. Rearrang ements and changes in chromosome number whitethorn touch on gene activity or gene transmission by modify the ________________________ of certain genes in a cell. A) position B) order C) number D) all of the above AnsD Difficulty2 24. Karyotypes generally remain constant within a species because A) rearrangements conk frequently. B) changes in chromosome number occur infrequently. C) communicable instabilities produced by genomic changes usually are at a selective disadvantage. D) familial imbalances are often at a selective advantage. AnsC Difficulty2 25. Despite endurance against chromosomal variations A) connect species almost always hold back the same karyotype. B) related species almost always have a different karyotype. C) almost related species diverge by many chromosomal rearrangements. D) distantly related species diverge by all a few chromosomal rearrangements. AnsB Difficulty2 26. In higher existences, employ genetic analysis is u sually difficult to distinguish teensy deletions in one gene from A) heterozygotes. B) small duplications. C) monosomies. D) point magnetic variations. AnsD Difficulty1 27. For an organism to break through a deletion of more than a few genes, it must carry a nondeleted homolog of the deleted chromosome. This is known as A) a deletion heterozygote. B) a deletion homozygote. C) dose compensation. D) a triplolethal chromosome. AnsA Difficulty2 28. Individuals born heterozygotes for certain deletions have a greatly increased risk of losing both copies of certain genes and create cancer. One such disease is A) triplolethal. B) scarlet eyes. C) retinoblastoma. D) cataracts. AnsC Difficulty1 29. During the pairing of homologs in prophase of meiosis I, the region of a frequent, nondeleted chromosome that has nonhing with which to recombine forms a questionable A) inversion loop. B) deletion heterozygote. C) crossover suppressor. D) deletion lo op. AnsD Difficulty2 30. Using Drosophila polytene chromosomes and small deletions, geneticists have been able to A) map the shaker-1 gene in Drosophila. B) assign genes to regions of one or devil polytene chromosome bands. C) assign genes to regions of 100kb or slight of DNA. D) all of the above AnsD Difficulty2 31. Which of the following molecular techniques could a scientist use to help locate genes on cloned fragments of DNA with deletion mutants? A) In situ hybridization B) Crossover analysis C) gray blot analysis D) all of the above E) both a and c AnsE Difficulty3 32. extras arise by A) chromosomal breakage and faulty repair. B) unequal crossing over. C) errors in replication. D) all of the above AnsD Difficulty1 33. During the pairing of homologs in prophase of meiosis I, the region of a chromosome bearing extra copies of a particular chromosomal region that has nothing with which to recombine forms a so-called A) inversion loop. B) deletion heterozygote. C) duplication loop. D) deletion loop. AnsC Difficulty2 34. An inversion may result from A) a half-circle rotation of a chromosomal region following ii double-strand breaks in a chromosomes DNA. B) the action of a transposable element. C) a crossover surrounded by DNA sequences present in two positions on the same chromosome in inverted orientation. D) all of the above E) none of the above AnsD Difficulty2 35. Inversions may be hard to detect because they A) never visibly change chromosome grade insignia patterns. B) increase recombination in heterozygotes. C) do not usually cause an ab formula phenotype. D) normally are withdraw immediately in natural populations. AnsC Difficulty3 36. Which of the following does not feel when an intragenic inversion occurs? A) One part of the gene is relocated to a distant region of the chromosome. B) One part of the gene stays at its original site. C) Homozygotes for the inversion do not survive. D) The genes manipulation is not disrupted. AnsD Difficulty3 37. When a crossover occurs within the inversion loop of a pericentric inversion each recombinant chromatid leave behind have A) a single centromere. B) a duplication of one region. C) a deletion different from the one of duplication. D) all of the above AnsD Difficulty2 38. Robertsonian translocations result from which of the following? A) Breaks at or near the centromeres of two acrocentric chromosomes followed by the reciprocal exchange of broken parts. B) A part of one chromosome becomes attached to a non-homologous chromosome. C) Unequal crossing over during meiosis. D) The fusion of two small chromosomes end-to-end such that a double centromere occurs. AnsA Difficulty2 39. Which of the following does not usually show a problem during meiosis? A) translocation heterozygotes B) translocation homozygotes C) paracentric inversion D) pericentric inversion AnsB Difficulty 1 40. Of the following separationism patterns, which one is most in all likelihood to result in a normal zygote? A) alternate B) adjacent-1 C) adjacent-2 D) nondisjunction AnsA Difficulty2 41. The condition of semisterility is most closely associated with A) chromosomal duplications. B) pericentric inversions. C) translocation heterozygotes. D) translocation homozygotes. AnsC Difficulty2 42. Translocations can help A) determine linkage groups. B) avail in the diagnosis and treatment of certain cancers. C) map important genes. D) all of the above AnsD Difficulty1 43. belt down Syndrome can result from A) three copies of chromosome 21. B) a translocation of a part of chromosome 21. C) a reciprocal translocation between any two autosomes. D) a and b E) a, b, and c AnsD Difficulty2 44. Which of the following do translocations and inversions not have in common? A) dont alter the amount of DNA in the genome B) ability to alter gene functio n C) use of inversion loops during crossing over D) catalysts of speciation AnsC Difficulty2 45. A transposition is considered a cytologically invisible sequence rearrangement. With which of the following does it section this property? A) small deletion B) large duplication C) inversion D) translocation AnsA Difficulty2 46. Barbara McClintock is most closely associated with which of the following? A) The initial discovery of genetic transposition. B) The discovery of transposable elements in corn. C) The mutation rate in translocation heterozygotes. D) The demonstration of the presence of transposable elements in polytene chromosomes. AnsB Difficulty1 47. Transposable elements have many things in common.Which of the following is not a usual characteristic of them? A) typically smaller than 50 bp. B) May be present in a genome from one to thousands of times. C) Are effect solo in a select group of organisms. D) Need not be sequences that do somet hing for the organism. AnsA Difficulty3 48. Retroposons and retro-viruses have structural parallels. Which of the following also shares structural parallels with them? A) tRNA B) DS-DNA C) rRNA D) mRNA AnsD Difficulty2 49. Which of the following is a possible effect that a transposable element may have on a gene? A) Shift the reading frame. B) Diminish the force of splicing. C) Provide a transcription stop head. D) all of the above AnsD Difficulty2 50. Which of the following is not an aneuploidy? A) monosomy B) tetraploid C) trisomy D) tetrasomy AnsB Difficulty1 51. The most common human aneuploidy is trisomy 21, Down syndrome.All of the effects listed below may be seen in this syndrome except A) death always by age 25. B) mental retardation. C) skeletal abnormalities. D) heart defects. E) increased susceptibility to infection. AnsA Difficulty2 52. Which of the following sex chromosome aneuploidies is not usually seen in live bir ths? A) XO B) XXY C) YO D) XXX E) None of the above AnsC Difficulty2 53. Turner syndrome, XO, is a sex chromosome aneuploidy. Of the effects listed below, which one is not usually seen in this syndrome? A) preposterously short stature B) infertility C) skeletal abnormalities D) unusually long limbs AnsD Difficulty2 54. In Drosophila, a gynandromorph, which is composed of equal parts male and womanish tissue, results from A) an XX female losing one X chromosome during the first mitotic division afterward fertilization. B) an egg carrying an X chromosome fertilized by a Y-carrying sperm. C) a normal egg fertilized by both an X-carrying sperm and a Y-carrying sperm. D) the fusion of a female embryo with a male embryo. AnsA Difficulty3 55. Which of the following is not an example of a euploid condition? A) triploidy B) diploidy C) Down syndrome D) tetraploidy AnsC Difficulty1 56. Triploid organisms usually result from A) the sum of money of haploid and diploid gametes. B) unequal disjunction during embryogenesis. C) propagation of fuse cell lines. D) fusion of three gametes simultaneously. AnsA Difficulty2 57. During mitosis, if the chromosomes in a diploid tissue fail to separate after replication, the resulting daughter cells will be A) monoploid. B) tetrasomic. C) triploid. D) tetraploid. AnsD Difficulty2 58. Hybrids in which the chromosome sets come from two distinct, though related, species are known as A) autopolyploids. B) allopolyploids. C) amphiploids. D) bivalents. AnsB Difficulty2 59. The genus Triticale is a naked genus of the various allopolyploid hybrids between wheat and rye whiskey.Some of the members of this genus show agricultural promise because A) wheat has a high yield. B) rye adapts well to unfavorable environments. C) wheat has a high train of protein. D) rye has a high level of lysine. E) all of the above AnsE Difficulty2 60. Which of the following rar ely, if ever, results in a ordained force for evolution? A) polyploidy B) allopolyploidy C) trisomy D) amphidiploidy AnsC Difficulty2 Matching Match the following descriptions with the toll below a. inversion b. duplication c. deletion d. translocation e. transposable element 61. A piece of genetic material that moves from place to place in the genome. Ans e Difficulty2 62. A change in the genome whereby new material is added to the genome. Ans b Difficulty1 63. A change in the genetic material where a DNA sequence changes direction. Ans a Difficulty1 64. A falling off of genetic material in the genome. Ans c Difficulty1 65. A piece of chromosome attaches to another chromosome. Ans d Difficulty2 Match the following descriptions with the terms below a. retroposon b. transposon c. transposable element d. transposase 66. Any DNA segment that moves about(predicate) in the genome. Ans c Difficulty3 67. Moves in the genome with the aid of an R NA intermediate. Ans a Difficulty2 68. Moves DNA directly. Ans b Difficulty3 69. An enzyme that catalyzes a transposition event. Ans d Difficulty1 on-key or False 70. When comparing mouse and human Giemsa-stained karyotypes, we see no conservation of banding patterns. Ans reliable Difficulty2 71. Karyotypes generally remain constant within a species because rearrangements and changes in chromosome number occur infrequently. AnsFalse Difficulty3 72. Changes in chromosome number include aneuploidy, monoploidy, polyploidy, and duplications. AnsFalse Difficulty2 73. Deletion may arise from errors in replication, from faulty meiotic or mitotic recombination, and from exposure to X-rays. Ans original Difficulty2 74. Homozygosity for a deletion is often, but not always, lethal. AnsTrue Difficulty2 75. Recessive mutations can often be covered by deletions in heterozygotes. AnsTrue Difficulty2 76. Most duplications have no obvious pheno typic consequences and can be spy only by cytological or molecular means. AnsFalse Difficulty2 77. Duplication of chromosomal segments rarely has an effect on the evolution of genomes. AnsTrue Difficulty2 78. Crossing-over within an inversion loop produces aberrant recombinant chromatids. AnsFalse Difficulty3 79. Reciprocal translocations are usually phenotypically abnormal because they have neither lost nor gained genetic material. AnsTrue Difficulty1 80. A hallmark of transposons is that their ends are inverted repeats of each other. AnsFalse Difficulty3 81. The mouse genome has high synteny with the human genome since about 170 DNA blocks are simply rearranged between the two genomes. AnsTrue Difficulty2 82. Euploid cells contain only incomplete sets of chromosomes. AnsFalse Difficulty2 83. Down syndrome is an example of triploidy. AnsFalse Difficulty2 84. Genetic imbalance results from polyploidy. AnsFalse Difficulty1 85. An acentric fragment is an inversion cross-over product lacking a centromere. AnsTrue Difficulty1 Short Answer 86. beg off how data from the linkage groups of the mouse can be used as a resource for assessing human linkage groups. Ans Because virtually all genes cloned from the mouse genome are conserved in the human genome and vice versa, it is possible to construct linkage maps for the two genomes from the same set of markers. Comparisons of the mouse and human linkage groups allow one to see a picture somewhere between complete correspondence and unrelatedness. Genes closely coupled in the mouse tend to be closely linked in humans, but genes that are less tightly linked in one species tend not to be linked at all in the other. This shows that even though mice and humans diverged about 65 million years ago, the DNA sequences in many regions are very similar. Difficulty4 87. Explain the differences between chromosomal rearrangements and changes in chromosome number. Cite at least one example of each. Ans Chromosomal rearrangements reorganize the DNA sequences within one or more chromosomes. Changes in chromosome number involve losings or gains of entire chromosomes or sets of chromosomes. (Student may cite as an example of rearrangements deletion, duplication, inversion, translocation, and transposable elements. For changes in chromosome number student may cite an aneuploidy such as a monosomy or trisomy, monoploidy, or polyploidy. Difficulty4 88. Describe how an inversion heterozygote can reduce the number of recombinant progeny. Ans When inversion heterozygotes have chromosomes pair up during meiosis, an inversion loop is formed to allow the tightest possible alignment of homologous regions. This always produces aberrant recombinant chromatids. dickens inversion cases are possible pericentric and paracentric. In a pericentric crossover within the inversion loop each recombinant will carry a duplication of one region and a deletion of another.This abnormal dosage of some genes will result in abnormal gametes and if they fertilize normal gametes, zygotes may die because of genetic imbalance. In a paracentric crossover within the inversion loop the recombinant chromatids will be unbalanced in both gene dosage and centromere number. (Student may then explain how centromere number can result in genetically unbalanced gametes such as what acentric and dicentric chromatids would produce. ) Difficulty4 89. hash out the several effects that translocations and inversions have in common. Ans Both translocations and inversions change genomic position without affecting the essential amount of DNA. If a breakpoint of either one is within a gene, the gene function may be altered or lost. Both types may produce genetically sick gametes that may negatively affect a zygote or developing embryo. (Student may explain at this point the differences between how the imbalanced gametes are produced. ) Because both reduce workable progeny and heterozygotes, they may play a role in speciation and evolution. Difficulty4 90. Explain the possible effects that a transposable element may have on a gene. Ans Insertion of a transposable element near or within a gene can affect gene style and alter phenotype. For example, a B type hemophilia occurs after insertion of Alu into the gene encoding clotting factor IX. Secondly, the effect of insertion depends on what the element is and where the insertion point is. If insertion is into a protein-coding exon, the reading frame may shift or a stop codon may be introduced. Insertion into an intron may lower the efficiency of splicing, which may result in removal from the transcript that could lower production of a normal polypeptide.A stop signal could also affect genes downstream. Upstream insertion into a regulatory gene could affect gene function in various ways also. Difficulty4 91. Explain the mechanism by which aneup loidy occurs. Ans Aneuploidy occurs because of meiotic nondisjunction either in meiosis I or meiosis II. In meiosis I if homologs do not separate all gametes produced will contain an error. Two of the gametes will contain both homologs and two will contain neither.When fertilization of a normal gamete occurs by either of these abnormal gametes, aneuploidy results. Half of the zygotes will be trisomic and half will be monosomic. Meiotic nondisjunction during meiosis II will produce two normal and two abnormal gametes. If fertilization occurs with either of the abnormal gametes, aneuploid zygotes are produced. Difficulty4 92. Discuss why triploid organisms are almost always sterile. Ans (Student may explain how triploids occur. ) Triploids are almost always sterile because meiosis produces mostly unbalanced gametes.During the first meiotic division in a triploid germ cell, three sets of chromosomes must segregate into two daughter cells. Most likely one daughter will end up with two chromosomes and the other will have only one of any one set of homologs. Some cells will have two of some chromosomes and the normal one of others. Many combinations of incorrect number of chromosomes will occur with very little chance of the normal amount. Most gametes will be aberrant and will have a reduced chance of producing viable offspring. Difficulty4 93. Discuss how deletions and duplications may wreak to evolution. Ans General examples of how chromosomal rearrangements might contribute to evolution Deletions a small deletion that moves a coding sequence of one gene adjacent to a promoter or other regulatory element of an adjacent gene may, rarely, allow expression of a protein at a novel time in development or in a novel tissue. If the new time or place of expression is advantageous to the organism, it might become naturalised in the genome. Duplications a duplication will provide at least two copies of a gene. If one copy maintains the original function, the other could conceivably acquire a new function that would probably be related to the original function.Many examples can be seen in higher plants and animals. (Students may also write about the evolutionary contributions of the other chromosomal rearrangements and might even mention the role of changes in chromosome number. ) Difficulty4 94. Why do inversions act as cross-over suppressors? Ans Inversions act as cross-over suppressors because only progeny that do not recombine within an inversion loop will survive. Difficulty4 95. What is a hangmans halter chromosome? Ans A balancer chromosome is a special chromosome often created by the use of X-rays for the purpose of genetic manipulation these chromosomes often carry multiple, overlapping inversions that enable researchers to follow them through crosses, and a recessive lethal mutation that prevents the survival of homozygotes. Difficulty4 96. What is the difference between alternate a nd an adjacent-1 segregation or an adjacent-2 segregation pattern? Ans An alternate segregation pattern results in balanced chromosomes while adjacent 1or 2 patterns yield chromosomes that are unbalanced. Difficulty4 Experimental Design and Interpretation of Data 97. We now know that several organisms have a high degree of synteny at the genomic level. You wish to test the hypothesis that the science laboratory mouse and human share genomic similarities. What tests would you complete and given that we now know that the mouse and human genomes are highly syntenic, what results would you expect? Ans Karyotype analysis can be used to test the hypothesis of genomic similarities however, only animals that have high homology will show similar banding patterns.Therefore, FISH (fluorescence in situ hybridization) would be a more useful technique to determine synteny. The mouse and human genomes are similar in that around 170 similar fragments an average length of about 18 M b are simply rearranged (this is not visible in a karyotype). Difficulty4 98. You are mapping traits in your favorite organism but unbeknownst to you, your laboratory model organism contains a rare deletion. How will your mapping results be affected? Ans The mapping outer space will appear smaller than the actual physical distance in the wild-type organism. Difficulty4 99. You have discovered an altered phenotype and cloned the gene responsible. However, the gene you cloned appears to have an unusual sequence in it. In order to determine the chromosomal location of your new gene, you perform FISH, using only the unusual sequence, on several animals. To your surprise, the FISH results suggest that each animal contains the gene on a different chromosome. How would you interpret your results. Ans The unusual sequence is a transposon and your new phenotype arose via the open frame of its gene by the transposon. Difficulty4 100. You are a master gardener and your favo rite tomato plant plant is very sensitive to a pesticide called DEADBUG. You wish to make your special tomato plants resistant to the pesticide which you atomiser on other bushes in your garden. Using microbial techniques give sufficient and complete details of how you would do this (include ploidy status). Ans Haploid pollen grains are cold do by and plated on agar plates.The resulting embryoids are hardened with hormone in liquid culture and eventually bighearted as a monoploid plant. The plant is treated with a mutagen to induce mutations that can result in insensitivity to the pesticide. Somatic cells are removed from the treated plant and plated on agar containing DEADBUG. Only cells resistant to DEADBUG will grow. Again the embryoid is hormone treated and grown into a resistant monoploid plant. Treatment with colchicine will allow duplication of chromosomes without separation resulting in a normal diploid plant. Difficulty4