Essentials of Genetics
9th Edition
ISBN: 9781292108933
Author: KLUG
Publisher: PEARSON
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Chapter 6, Problem 1PDQ
HOW DO WE KNOW?
In this chapter, we 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
(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
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Chapter 6 Solutions
Essentials of Genetics
Ch. 6 - CASE STUDY| Fish tales Aquatic vegetation...Ch. 6 - CASE STUDY |Fish tales Aquatic vegetation...Ch. 6 - CASE STUDY |Fish tales
Aquatic vegetation...Ch. 6 - HOW DO WE KNOW? In this chapter, we focused on...Ch. 6 -
CONCEPT QUESTION
2. Review the Chapter Concepts...Ch. 6 -
3. Define these pairs of terms, and distinguish...Ch. 6 -
4. For a species with a diploid number of 18,...Ch. 6 - What explanation has been proposed to explain why...Ch. 6 - Contrast the fertility of an allotetraploid with...Ch. 6 -
7. Why do human monosomies most often fail to...
Ch. 6 -
8. Describe the origin of cultivated American...Ch. 6 - Predict how the synaptic configurations of...Ch. 6 - Inversions are said to “suppress crossing over.”...Ch. 6 -
11. Predict the genetic composition of gametes...Ch. 6 - Human adult hemoglobin is a tetramer containing...Ch. 6 -
13. The primrose, Primula kewensis, has 36...Ch. 6 - Certain varieties of chrysanthemums contain 18,...Ch. 6 - Drosophila may be monosomic for chromosome 4, yet...Ch. 6 - Mendelian ratios are modified in crosses involving...Ch. 6 -
17. Having correctly established the F2 ratio in...Ch. 6 -
18. In a cross between two varieties of corn,...Ch. 6 -
19. A couple planning their family are aware that...Ch. 6 -
20. A woman who sought genetic counseling is...Ch. 6 - The woman in Problem 20 has had two miscarriages....Ch. 6 -
22. In a recent cytogenetic study on 1021 cases...Ch. 6 -
23. A boy with Klinefelter syndrome (47,XXY) is...Ch. 6 - In a human genetic study, a family with five...Ch. 6 - A 3-year-old child exhibited some early indication...Ch. 6 - A normal female is discovered with 45 chromosomes,...
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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
- Campomelic dysplasia (CMD1) is a congenital humansyndrome featuring malformation of bone and cartilage.It is caused by an autosomal dominant mutation of agene located on chromosome 17. Consider the followingobservations in sequence, and in each case, draw whateverappropriate conclusions are warranted.(a) Of those with the syndrome who are karyotypically46,XY, approximately 75 percent are sex reversed,exhibiting a wide range of female characteristics.(b) The nonmutant form of the gene, called SOX9, isexpressed in the developing gonad of the XY male,but not the XX female.(c) The SOX9 gene shares 71 percent amino acid codingsequence homology with the Y-linked SRY gene.(d) CMD1 patients who exhibit a 46,XX karyotypedevelop as females, with no gonadal abnormalities.arrow_forwardthe deletion of which chromosome causes obvious morphological and mental defects in the organism, such as microcephaly, strabismus, major mental retardation and is known as the 'cri-du-chat' syndrome?arrow_forwardWhat unusual feature of the Y chromosome allows some recombination among the genes found on it?arrow_forward
- Why is a chromosomal fragment without a centromeresubsequently lost and degraded?arrow_forward. With regards to the grasshopper testes experiment, diakinesis is an ideal stage to determine chromosome number due to the degree of condensation of the chromosomes? Count the chromosomes at this stage. Does it represent a diploid or a haploid number?arrow_forwardTwo phenotypically normal parents produce a phenotypically abnormal child in which chromosome 5 is missing part of its long arm but has a piece of chromosome 7 attached to it. The child also has one normal copy of chromosome 5 and two normal copies of chromosome 7. With regard to chromosomes 5 and 7, what do you think are the chromosomal compositions of the parents? Would it most likely be reciprocal translocation? It wouldn't be simple translocation because then the child would have the entirety of one chromosome and only some of the other, but in this case, there is only partial chromosome 5 and chromosome 7?arrow_forward
- What is the underlying genetic defect that causes xeroderma pigmentosum?How can the symptoms of this disease be explained by the genetic defect?arrow_forwardWhy is chromosome 21 Down syndrome?arrow_forwardAn individual is heterozygous for a reciprocal translocation, with the following chromosomes: A • B C D E F A • B C V W X R ST • U D E F R ST • U V W X Q. Explain why the fertility of this individual is likely to be less than the fertility of an individual without a translocation.arrow_forward
- Here are the results of the testcross:Green-eyes, wild-type wings 245Green-eyes, miniature wings 232Wild-type eyes, wild-type wings 250Wild-type eyes, miniature wings 2386.) In your opinion, is the grn gene on the same chromosome as the min gene? How do you know?Next, you set up another experiment to determine if grn is on chromosome #1. The only appropriate fliesthat you have handy are double-mutants for the black-body mutation (blk) and curved wings mutation(crv), but this should work just fine. First, you conduct a series of crosses to generate a strain of triple-mutant flies (grn blk crv). Then, you cross those with wild-type flies to generate triple hybrids.7.) What are the genotype(s) and phenotype(s) of the progeny of this cross?Next, you set up a testcross to reveal any linkage between the three genes.8.) What are the genotypes and phenotypes of this testcross?arrow_forwardWhy is chromosome 21 the smallest and not chromosome 22? considering that a karyogram is arranged from largest to smallestarrow_forwardKuliev and Verlinsky (2004) state that there was a relatively high number of separation errors at meiosis I. In these cases the centromere underwent a premature division, occurring at meiosis I rather than meiosis II. Regarding chromosome 21, what would you expect to be the chromosome 21 complement in the secondary oocyte in which you saw a single chromatid (monad) for chromosome 21 in the first polar body? If this secondary oocyte was involved in fertilization, what would be the expected consequences?arrow_forward
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