A cytogeneticist has collected tissue samples from members of acertain butterfly species. Some of the butterflies were located inCanada, and others were found in Mexico. Through karyotyping,the cytogeneticist discovered that chromosome 5 of the Canadianbutterflies had a large inversion compared with chromosome 5 ofthe Mexican butterflies. The Canadian butterflies were inversionhomozygotes, whereas the Mexican butterflies had two normalcopies of chromosome 5.Explain whether a mating between Canadian and Mexicanbutterflies would produce phenotypically normal offspring?

A cytogeneticist has collected tissue samples from members of acertain butterfly species. Some of the butterflies were located inCanada, and others were found in Mexico. Through karyotyping,the cytogeneticist discovered that chromosome 5 of the Canadianbutterflies had a large inversion compared with chromosome 5 ofthe Mexican butterflies. The Canadian butterflies were inversionhomozygotes, whereas the Mexican butterflies had two normalcopies of chromosome 5.Explain whether a mating between Canadian and Mexicanbutterflies would produce phenotypically normal offspring?

Name: A cytogeneticist has collected tissue samples from members of acertain
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Description: A cytogeneticist has collected tissue samples from members of acertain butterfly species. Some of the butterflies were located inCanada, and others were found in Mexico. Through karyotyping,the cytogeneticist discovered that chromosome 5 of the Canad

Human Biology (MindTap Course List)

11th Edition

ISBN:9781305112100

Author:Cecie Starr, Beverly McMillan

Publisher:Cecie Starr, Beverly McMillan

Chapter20: Chromosomes And Human Genetics

Section: Chapter Questions

Problem 3CT: People with Down syndrome have an extra copy of chromosome 21, for a total of 47 chromosomes....

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A colleague e-mails you saying that she has identified an interesting chromosome variation at 21q13. In discussing this discovery with a friend who is not a cytogeneticist, explain how you would describe this location, defining each term in the chromosome address 21q13.
Variations in Chromosome NumberAneuploidy Describe the process of nondisjunction and explain when it takes place during cell division.
Assume that a meiotic-nondisjunction event causes trisomy 8 in a newborn. If two of the three copies of chromosome 8 are absolutely identical, at what point during meiosis did the nondisjunction event take place?
A cytogeneticist has collected tissue samples from members of a certain butterfly species. Some of the butterflies were located in Canada, and others were found in Mexico. Through karyotyping, the cytogeneticist discovered that chromosome 5 of the Canadian butterflies has a large inversion compared with chromosome 5 of the Mexican butterflies. The Canadian butterflies were inversion homozygotes, whereas the Mexican butterflies had two normal copies of chromosome 5. 1) Would a cross between Mexican and Canadian butterflies produce phenotypically normal offspring? and 2) Would the offspring of the cross (so F2 generation) be fertile?
Genes that cause Prader-Willi syndrome and Angelman syndromeare closely linked along chromosome 15. Although people withthese syndromes do not usually reproduce, let’s suppose that acouple produces two children with Angelman syndrome. The oldest child (named Pat) grows up and has two children with PraderWilli syndrome. The second child (named Robin) grows up andhas one child with Angelman syndrome.A. Are Pat and Robin’s parents both phenotypically normal ordoes one of them have Angelman or Prader-Willi syndrome? Ifone of them has a disorder, state whether it is the mother or thefather, and explain how you know.B. What are the sexes of Pat and Robin? Explain.
The karyotype of a young girl who is affected with familialDown syndrome revealed a total of 46 chromosomes. Her olderbrother, however, who is phenotypically unaffected, actually had45 chromosomes. Explain how this could happen. What wouldyou expect to be the numbers of chromosomes in the parents ofthese two children?
While conducting field studies on a chain of islands, you decide tokaryotype two phenotypically identical groups of turtles, which arefound on different islands. The turtles on one island have 24 chromosomes,but those on another island have 48 chromosomes. Howwould you explain this observation? How do you think the turtleswith 48 chromosomes came into being? If you crossed the twotypes of turtles, would you expect the offspring to be phenotypicallynormal? Would you expect them to be fertile? Explain.
Genes that cause Prader-Willi syndrome and Angelman syndromeare closely linked along chromosome 15. Although people withthese syndromes do not usually reproduce, let’s suppose that acouple produces two children with Angelman syndrome. The oldestchild (named Pat) grows up and has two children with Prader-Willi syndrome. The second child (named Robin) grows up andhas one child with Angelman syndrome.A. Are Pat and Robin’s parents both phenotypically normal ordoes one of them have Angelman or Prader-Willi syndrome? Ifone of them has a disorder, state whether it is the mother or thefather, and explain how you know.B. What are the sexes of Pat and Robin?
In humans, chromosome 16 sometimes has a heavily stained area in the long arm near the centromere. This feature can be seen through the microscope but has no effect on the phenotype of the person carrying it. When such a “blob” exists on a particular copy of chromosome 16, it is a constant feature of that chromosome and is inherited. A couple conceived a child, but the fetus had multiple abnormalities and was miscarried. When the chromosomes of the fetus were studied, it was discovered that it had three copies of chromosome 16 (it was trisomic for chromosome 16), and that two of the three chromosome 16s had large blobs. Both chromosome 16 homologs in the mother lacked blobs, but the father was heterozygous for blobs. Which parent experienced nondisjunction, and in which meiotic division did it occur?
A woman with an abnormally long chromosome 13 (and a normalhomolog of chromosome 13) has children with a man with anabnormally short chromosome 11 (and a normal homolog of chromosome 11). What is the probability of producing an offspringthat will have both a long chromosome 13 and a short chromosome11? If such a child is produced, what is the probability that thischild will eventually pass both abnormal chromosomes to one ofhis or her offspring?
crossing over within a pericentric inversion produces chromosomes that have extra copies of some genes and no copies of other genes. The fertilization of gametes containing chromosomes with duplications or deletions often result in children with syndromes characterized by developmental delay, intellectual disability, abnormal development of organ systems, and early death. Maarit Jaarola and colleagues examined individual sperm cells of a male who was heterozygous for a pericentric inversion on chromosome 8 and determined that crossing over took place within the pericentric inversion in 26% of the meiotic divisions (M. Jaarola, R. H. Martin, and T. Ashley. 1998. American Journal of Human Genetics 63:218–224). Assume that you are a genetic counselor and that a couple seeks counseling from you. Both the man and the woman are phenotypically normal, but the woman is heterozygous for a pericentric inversion on chromosome 8. The man is karyotypically normal. What is the probability that this…
The normal sequence of nine genes on a certainDrosophila chromosome is 123 • 456789, where the dotrepresents the centromere. Some fruit flies were foundto have aberrant chromosomes with the followingstructures:a. 123 • 476589 c. 1654 • 32789b. 123 • 46789 d. 123 • 4566789Name each type of chromosomal rearrangement, anddraw diagrams to show how each would synapse withthe normal chromosome.