Human Heredity: Principles and Issues (MindTap Course List)
11th Edition
ISBN: 9781305251052
Author: Michael Cummings
Publisher: Cengage Learning
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Chapter 6, Problem 24QP
A geneticist discovers that a girl with Down syndrome has a Robertsonian translocation involving chromosomes 14 and 21. If she has an older brother who is
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A boy with Down syndrome (trisomy 21) has 46 chromosomes. One parent and his two older sisters have a normal phenotype, but each have 45 chromosomes.
a)Explain how this is possible.
b)How many chromosomes do you expect to see in karyotypes of the parents?
c)What term best describes this kind of chromosome abnormality?
d)What is the probability the next child of this couple will have a normal phenotype and have 46 chromosomes? Explain your answer.
In a sample of 1000 patients with Down syndrome, a geneticist discovers that 95% of them are trisomic, while 5% have diploid number of chromosomes. Explain this discrepancy.
Two phenotypically unaffected parents produce two children with familial Down syndrome. Regarding chromosome 14 and 21, what are the chromosomal composition of the parents?
Chapter 6 Solutions
Human Heredity: Principles and Issues (MindTap Course List)
Ch. 6 - Genetics in Practice case studies are...Ch. 6 - Genetics in Practice case studies are...Ch. 6 - Analyzing Karyotypes 1. Originally, karyotypic...Ch. 6 - Given the karyotype shown at right, is this a male...Ch. 6 - A colleague e-mails you saying that she has...Ch. 6 - What are the two most commonly used methods of...Ch. 6 - Prob. 5QPCh. 6 - Discuss the following sets of terms: a. trisomy...Ch. 6 - What chromosomal abnormality can result from...Ch. 6 - Tetraploidy may result from: a. lack of...
Ch. 6 - A cytology student believes he has identified an...Ch. 6 - An individual is found to have some tetraploid...Ch. 6 - A spermatogonial cell undergoes mitosis before...Ch. 6 - A teratogen is an agent that produces nongenetic...Ch. 6 - As a physician, you deliver a baby with protruding...Ch. 6 - Variations in Chromosome NumberAneuploidy Describe...Ch. 6 - A woman gives birth to monozygotic twins. One boy...Ch. 6 - Assume that a meiotic-nondisjunction event causes...Ch. 6 - Prob. 17QPCh. 6 - What is the genetic basis and phenotype for each...Ch. 6 - The majority of nondisjunction events leading to...Ch. 6 - Prob. 20QPCh. 6 - If all the nondisjunction events leading to Turner...Ch. 6 - Identify the type of chromosomal aberration...Ch. 6 - Describe the chromosomal alterations and phenotype...Ch. 6 - A geneticist discovers that a girl with Down...Ch. 6 - Albinism is caused by an autosomal recessive...Ch. 6 - Fragile-X syndrome causes the most common form of...
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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
- Two phenotypically unaffected parents produce two children withfamilial Down syndrome. With regard to chromosomes 14 and 21,what are the chromosomal compositions of the parents?arrow_forwardBelow is a pedigree from one family (two parents and eight children). Four of the children (indicated by shaded shapes) are affected with a serious disease with an unknown genetic cause. a) For the disease, what pattern of inheritance (autosomal/sex-linked, recessive/dominant) is exhibited by this pedigree? b) Linkage analysis of the disease to a series of VNTR polymorphisms on human chromosome 5 is shown above. Is there evidence for linkage between the disorder and the VNTR? Briefly explain your answer.arrow_forwardIn a diploid organism of 2n=10, assume that you can label all the centromeres derived from its female parent and all the centromeres derived from its male parent. When this organism produces gamestes, how many male and female-labeled centromere combinations are possible in the gametes?arrow_forward
- Two 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_forwardIn a human genetic study, a family with five phenotypicallynormal children was investigated. Two children were “homozygous”for a Robertsonian translocation between chromosomes19 and 20 (they contained two identical copies of the fusedchromosome). They have only 44 chromosomes but a completegenetic complement. Three of the children were “heterozygous”for the translocation and contained 45 chromosomes,with one translocated chromosome plus a normal copy of bothchromosomes 19 and 20. Two other pregnancies resulted instillbirths. It was later discovered that the parents were firstcousins. Based on this information, determine the chromosomecompositions of the parents. What led to the stillbirths? Whywas the discovery that the parents were first cousins a key pieceof information in understanding the genetics of this family?arrow_forwardWhich members of the pedigree could have been carriers, and which might have been the source of the mutation?arrow_forward
- A normal mother has translocations on chromosomes 14:21. With respect to chromosomes 14:21, how many combinations of chromosomes are possible? How many gametes are viable? If the woman has children with an normal father, what is the probability that there is a daughter with Down Syndrome or a son with an unaffected phenotype?arrow_forwardWhat occurs during duplication chromosomal mutation?arrow_forwardWhat is a microdeletion?arrow_forward
- What is a balanced chromosomal rearrangement?arrow_forwardIn humans, chromosome 16 sometimes has a heavily stained area near the centromere. This feature can be seen in a microscope, but otherwise has no effect on the phenotype of the person carrying it. When such a “blob" exists on a given 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. e.g., The fetus had three copies of chromosome 16, where 2 of the 3 copies of chromosome 16 had large blobs. Both of the mother's copies of chromosome 16 lacked blobs, but the father was heterozygous for blobs. The fetus was formed from a fertilization event that included a gamete produced by the in which nondisjunction occurred during the meiotic division. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a mother; first. mother; second. father; first. C Your answer d father; second. E3 Fullso L e Insufficient information is provided…arrow_forwardWhat causes Robertsonian translocation?arrow_forward
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