Genetics: From Genes to Genomes
6th Edition
ISBN: 9781259700903
Author: Leland Hartwell Dr., Michael L. Goldberg Professor Dr., Janice Fischer, Leroy Hood Dr.
Publisher: McGraw-Hill Education
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Chapter 13, Problem 38P
Down syndrome is usually caused by having a complete extra copy of chromosome 21. The syndrome encompasses many different traits including low IQ, heart disease, characteristic facial features, gastrointestinal tract abnormalities, short stature, poor muscle tone, and increased risk of leukemia and dementia. Some people diagnosed with Down syndrome display only a subset of these anomalies. These people often have one normal chromosome 21 and one chromosome 21 containing a duplication; the region of chromosome 21 that is duplicated can differ among individuals.
Some scientists think that one critical region of chromosome 21 exists (containing one or a few genes) that is responsible for Down syndrome. Researchers have used individuals with duplication Down syndrome to test this idea. Suppose that using genome sequencing, scientists determined which parts of chromosome 21 were present in three copies in eight individuals with duplication Down syndrome. A summary of the data is shown in the table that follows. An X indicates that the given individual is affected by the particular abnormality listed in the column heading.
| a. | Do the data support or refute the hypothesis that chromosome 21 contains a single Down syndrome critical region? Explain. |
| b. | Do the data support the idea that each Down syndrome abnormality is caused by overexpression of a different region of chromosome 21? Explain. |
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Familial Down syndrome is similar to primary Down syndrome in that it is caused by trisomy 21. However, in familial Down syndrome,
all or part of the third copy of chromosome 21 has translocated onto another autosome, typically chromosome 14. In cases of familial
Down syndrome, one of the parents of the affected child is often a carrier of a translocated chromosome. The translocation carrier
parent does not have Down syndrome because he or she has a total of two copies of chromosome 21.
Suppose that a woman is a translocation carrier of chromosome 21 on chromosome 14. She conceives six zygotes with a man who
carries no aneuploidies. Match the description of the chromosomes inherited by each zygote with the viability and phenotype of
the zygote.
✓ Two normal copies of 14, two normal copies of 21
two normal copies of 21, one normal copy of 14
✓one normal copy of 14, one 21 to 14 translocation, one
normal copy of 21
✓two normal copies of 14, one normal copy of 21, on 21 to 14…
In 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.
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select an answer.
a
mother; first.
mother; second.
father; first.
C
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d
father; second.
E3 Fullso
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e
Insufficient information is provided…
Neurofibromatosis 1 is considered an autosomal dominant disorder because the gene is located on the long arm of chromosome 17. It is caused by microdeletion at the long arm of chromosome 17 band 11 sub-band 2 involving the NF1 gene.
Group of answer choices
Statement 1 is correct. Statement 2 is incorrect
Statement 1 is incorrect, statement 2 is correct
Both statements are incorrect
Both statements are correct
Chapter 13 Solutions
Genetics: From Genes to Genomes
Ch. 13 - For each of the terms in the left column, choose...Ch. 13 - Prob. 2PCh. 13 - For each of the following types of chromosomal...Ch. 13 - For the following types of chromosomal...Ch. 13 - One of the X chromosomes in a particular...Ch. 13 - A diploid strain of yeast was made by mating a...Ch. 13 - The two graphs that follow represent genomic...Ch. 13 - A series of chromosomal mutations in Drosophila...Ch. 13 - Indicate which of the four major classes of...Ch. 13 - The recessive, X-linked z1 mutation of the...
Ch. 13 - Genes a and b are 21 m.u. apart when mapped in...Ch. 13 - In the following group of figures, the pink lines...Ch. 13 - Three strains of Drosophila Bravo, X-ray, and...Ch. 13 - Two yeast strains were mated and sporulated...Ch. 13 - Suppose a haploid yeast strain carrying two...Ch. 13 - In the mating between two haploid yeast strains...Ch. 13 - During ascus formation in Neurospora, any...Ch. 13 - In the following figure, black and pink lines...Ch. 13 - In Drosophila, the gene for cinnabar eye color is...Ch. 13 - Semisterility in corn, as seen by unfilled ears...Ch. 13 - A promising biological method for insect control...Ch. 13 - Prob. 23PCh. 13 - a. Among the progeny of a self-fertilized...Ch. 13 - Duchenne muscular dystrophy DMD is caused by a...Ch. 13 - WHIM syndrome is a disease of the immune system...Ch. 13 - Explain how transposable elements can cause the...Ch. 13 - The Drosophila genome normally harbors about 40 P...Ch. 13 - Drosophila P elements were discovered because of a...Ch. 13 - Flies homozygous for mutant alleles of a...Ch. 13 - Fred and Mary have a child named Bob. The genomic...Ch. 13 - Uniparental disomy is a rare phenomenon in which...Ch. 13 - Among adults with Turner syndrome, it has been...Ch. 13 - In Neurospora, his2 mutants require the amino acid...Ch. 13 - Human geneticists interested in the effects of...Ch. 13 - The incidence of Down syndrome will be very high...Ch. 13 - The Drosophila chromosome 4 is extremely small;...Ch. 13 - Down syndrome is usually caused by having a...Ch. 13 - Common red clover, Trifolium pratense, is a...Ch. 13 - The numbers of chromosomes in the somatic cells of...Ch. 13 - Prob. 41PCh. 13 - Somatic cells in organisms of a particular diploid...Ch. 13 - An allotetraploid species has a genome composed of...Ch. 13 - Prob. 44PCh. 13 - Chromosomes normally associate during meiosis I as...Ch. 13 - Using whole-genome sequencing, how could you...Ch. 13 - Prob. 47PCh. 13 - Prob. 48PCh. 13 - Seedless watermelons that you find in the...Ch. 13 - The names of hybrid animals are usually themselves...Ch. 13 - While most animals cannot tolerate polyploidy,...Ch. 13 - What characteristic property of translocations...Ch. 13 - Prob. 53PCh. 13 - In the accompanying figure, the top and bottom...Ch. 13 - Prob. 55PCh. 13 - The accompanying figure shows idiograms of human...Ch. 13 - Prob. 57P
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- 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?arrow_forwardWhy is the incidence of survivable genetic disorders involving deletions of parts of chromosomes so rare? Why is the incidence of trisomy of larger chromosomes rarer than the incidence of trisomy of smaller chromosomes? What is the relationship between the severity of symptoms and the size of chromosome involved in the trisomy?arrow_forwarddescribe a specific example of chromosome abnormality that leads to human cancers, such as leukemia, other than the Philadelphia chromosome that is derived from the translocation of chromosome 9 and 22arrow_forward
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