Concepts of Genetics (11th Edition)
11th Edition
ISBN: 9780321948915
Author: William S. Klug, Michael R. Cummings, Charlotte A. Spencer, Michael A. Palladino
Publisher: PEARSON
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Chapter 8, Problem 1PDQ
HOW DO WE KNOW? In this chapter, we have focused on chromosomal mutations resulting from a change in number or arrangement of chromosomes. In our discussions, we found many opportunities to consider the methods and reasoning by which much of this information was acquired. From the explanations given in the chapter, what answers would you propose to the following fundamental questions?
- (a) How do we know that the extra chromosome causing Down syndrome is usually maternal in origin?
- (b) How do we know that human aneuploidy for each of the 22 autosomes occurs at conception, even though most often human aneuploids do not survive embryonic or fetal development and thus are never observed at birth?
- (c) How do we know that specific mutant
phenotypes are due to changes in chromosome number or structure? - (d) How do we know that the mutant Bar-eye phenotype in Drosophila is due to a duplicated gene region rather than to a change in the
nucleotide sequence of a gene?
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Chapter 8 Solutions
Concepts of Genetics (11th Edition)
Ch. 8 - A human female with Turner syndrome (47, X) also...Ch. 8 - When two plants belonging to the same genus but...Ch. 8 - What is the effect of a rare double crossover (a)...Ch. 8 - Prob. 1CSCh. 8 - Prob. 2CSCh. 8 - Aquatic vegetation overgrowth, usually controlled...Ch. 8 - HOW DO WE KNOW? In this chapter, we have focused...Ch. 8 - Review the Chapter Concepts list on page 171....Ch. 8 - Define these pairs of terms, and distinguish...Ch. 8 - For a species with a diploid number of 18,...
Ch. 8 - What evidence suggests that Down syndrome is more...Ch. 8 - What evidence indicates that humans with aneuploid...Ch. 8 - Contrast the fertility of an allotetraploid with...Ch. 8 - Describe the origin of cultivated American cotton.Ch. 8 - Predict how the synaptic configurations of...Ch. 8 - Inversions are said to suppress crossing over. Is...Ch. 8 - Contrast the genetic composition of gametes...Ch. 8 - Human adult hemoglobin is a tetramer containing...Ch. 8 - Discuss Ohnos hypothesis on the role of gene...Ch. 8 - What roles have inversions and translocations...Ch. 8 - The primrose, Primula kewensis, has 36 chromosomes...Ch. 8 - Certain varieties of chrysanthemums contain 18,...Ch. 8 - Drosophila may be monosomic for chromosome 4, yet...Ch. 8 - Mendelian ratios are modified in crosses involving...Ch. 8 - Having correctly established the F2 ratio in...Ch. 8 - The mutations called bobbed in Drosophila result...Ch. 8 - The outcome of a single crossover between...Ch. 8 - A couple planning their family are aware that...Ch. 8 - In a cross in Drosophila, a female heterozygous...Ch. 8 - A woman who sought genetic counseling is found to...Ch. 8 - Prob. 25ESPCh. 8 - In a recent cytogenetic study on 1021 cases of...Ch. 8 - A boy with Klinefelter syndrome (47,XXY) is born...Ch. 8 - Prob. 28ESPCh. 8 - Prob. 29ESPCh. 8 - A 3-year-old child exhibited some early indication...Ch. 8 - A normal female is discovered with 45 chromosomes,...Ch. 8 - Prob. 32ESP
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.Similar questions
- The wild-type (normal) fruit fly, Drosophila melanogaster, has straight wings and long bristles. Mutant strains have been isolated that have either curled wings or short bristles. The genes representing these two mutant traits are located on separate chromosomes. Carefully examine the data from the following five crosses shown below (running across both columns). (a) Identify each mutation as either dominant or recessive. In each case, indicate which crosses support your answer. (b) Assign gene symbols and, for each cross, determine the genotypes of the parents.arrow_forwardWhen a female melanotic fly is crossed with a normal male, the progeny are produced: 123 normal females, 125 melanotic females, and 124 normal males. In subsequent crosses between melanotic females and normal males, melanotic females are frequently obtained, but never any melanotic males. Provide a possible explanation for the inhertiacne of the melanotic mutation (Hint: The cross produces twice as many female progeny as male progeny)arrow_forwarda)What is the synaptonemal complex? b)Why are the X and Y chromosomes not considered homologous even though they recombine at the PAR region? c)What is unique about the Y chromosome?arrow_forward
- An individual has a deletion of part of the short arm of chromosome 5. This individual also has a normal copy of chromosome 5. Would you expect this individual to have Cri-du-chat syndrome? Why or why not? Question 7 options: A) Yes, because they will inactivate their normal chromosome 5 B) Yes, because they only contain one copy of some of their genes C) No, because this is a terminal deficiency D) No, because they still have at least one copy of all the genes on chromosome 5arrow_forwardThe woman in Problem 24 has had two miscarriages. She has come to you, an established genetic counselor, with these questions: Is there a genetic explanation of her frequent miscarriages? Should she abandon her attempts to have a child of her own? If not, what is the chance that she could have a normal child? Provide an informed response to her concerns.arrow_forwardWith detailed accounts of their various forms, explain any three of the following chromosomal aberrations: a) Deletions b) Duplications c) Translocations d)Inversionarrow_forward
- Answer the following questions: A) Why the extension cannot be 3´---5´ and why it has to be 5´------3´? B) What is a gene?arrow_forwardHumans and many other complex organisms are diploid, possessing two sets of genes, one inherited from the mother and one from the father. However, a number of eukaryotic organisms spend most of their life cycles in a haploid state. Many of these eukaryotes, such as Neurospora and yeast, still undergo meiosis and sexual reproduction, but most of the cells that make up the organism are haploid. Considering that haploid organisms are fully capable of sexual reproduction and generating genetic variation, why are most complex eukaryotes diploid? In other words, what might be the evolutionary advantage of existing in a diploid state instead of a haploid state? And why might a few organisms, such as Neurospora and yeast, exist as haploids?arrow_forwardMutations in the HPRT1 gene in humans result in atleast two clinical syndromes. Consult OMIM (www.omim.org) by querying HPRT1; you will only needto look briefly at the top three hits (files #300322,300323, and 308000).a. What is the full name of the HPRT1 enzyme?b. On which chromosome is the HPRT1 gene located?c. Mutations in HPRT1 are associated with two different syndromes. What are these syndromes? Foreach, answer the following questions: (i) What arethe symptoms associated with the syndrome? (ii) Isthe mutant allele that causes the syndrome dominant, recessive, codominant, or incompletely dominant with respect to the normal allele, or do specialconditions apply? (iii) Is the syndrome associatedwith a loss-of-function or a gain-of-function disease allele? (iv) Does the syndrome display allelicheterogeneity? (v) Does the syndrome display locus heterogeneity? (Note: You do not need to understand everything in the OMIM entries to answerthese questions.)arrow_forward
- Which type(s) of chromosomal aberrations result from chromosomal breaks on different chromosomes? Assume that a heterozygote for the aberration is viable. Select all correct answers. A.)Robertsonian translocation B.)reciprocal translocation C.)tandem duplication D.)paracentric inversion E.)pericentric inversion F.)large deletionarrow_forwardSelect the statements below that are TRUE. Select 4 correct answer(s) Question 14 options: A) Mutations are induced to occur in response to a selective pressure. B) Crossover suppression occurs when no recombinant progeny are observed between two genes located within a homozygous paracentric inversion. C) The ends of each chromosome are replicated by an RNA-protein complex called telomerase. D) When a mismatched base pair occurs during DNA replication, mismatch repair corrects the mismatch by replacing the nucleotide on the template strand. E) Mutations occur spontaneously and so may be pre-existing in a population when a selective pressure arises. F) When two genes are linked, the frequency of recombinant types exceeds the frequency of parental types. G) The choice…arrow_forward(a) Explain the relationship between DNA, genes, and chromosomes during the passing of genetic information. (b) During the passing of genetic information from one generation to the next via chromosomes, nondisjunction can occur, interrupting the process. Describe the events that take place during nondisjunction.arrow_forward
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