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Sanders 3rd EditionCh. 10 - Eukaryotic Chromosome Abnormalities and Molecular OrganizationProblem B.11b
The most common reason a physician might recommend that a woman have maternal serum screening and a karyotype analysis is concern that her fetus may have Down syndrome. Go to the OMIM website at www.ncbi.nlm.nih.gov/omim and look up Down syndrome (OMIM 190685).
Look at the 'Mapping' and 'Molecular Genetics' sections and describe what is meant by the Down syndrome critical region (DSCR).
Problem B.11a
The most common reason a physician might recommend that a woman have maternal serum screening and a karyotype analysis is concern that her fetus may have Down syndrome. Go to the OMIM website at www.ncbi.nlm.nih.gov/omim and look up Down syndrome (OMIM 190685).
List the main symptoms of Down syndrome.
Problem B.11d
The most common reason a physician might recommend that a woman have maternal serum screening and a karyotype analysis is concern that her fetus may have Down syndrome. Go to the OMIM website at www.ncbi.nlm.nih.gov/omim and look up Down syndrome (OMIM 190685).
How might those genes lead to the main symptoms of Down syndrome?
Problem B.11c
The most common reason a physician might recommend that a woman have maternal serum screening and a karyotype analysis is concern that her fetus may have Down syndrome. Go to the OMIM website at www.ncbi.nlm.nih.gov/omim and look up Down syndrome (OMIM 190685).
Summarize what is known about the location and genes found within the DSCR.
Problem 1a
Give descriptions for the following terms:
Histone proteins
Problem 1b
Give descriptions for the following terms:
Nucleosome core particle
Problem 1c
Give descriptions for the following terms:
Scaffold proteins
Problem 1d
Give descriptions for the following terms:
G bands
Problem 1e
Give descriptions for the following terms:
Euchromatin
Problem 1f
Give descriptions for the following terms:
Heterochromatin
Problem 1g
Give descriptions for the following terms:
Nucleosome
Problem 1h
Give descriptions for the following terms:
Chromosome territory
Problem 2
The human genome contains 2.9×10⁹ base pairs. Approximately how many nucleosomes are required to organize the 10-nm–fiber structure of the human genome? Show the calculation you use to determine the answer.
Problem 3a
In eukaryotic DNA, where are you most likely to find histone protein H4?
Problem 3b
In eukaryotic DNA, where are you most likely to find histone protein H1?
Problem 3c
In eukaryotic DNA, along a 6000-bp segment of DNA, approximately how many molecules of each kind of histone protein do you expect to find? Explain your answer.
Problem 3d
In eukaryotic DNA, how does the role of H1 differ from the role of H3 in chromatin formation?
Problem 4
Describe the importance of light and dark G bands that appear along chromosomes.
Problem 5
Human late prophase karyotypes have about 2000 visible G bands. The human genome contains approximately 22,000 genes. Consider the region 5p1.5 through the end of the short arm of chromosome 5, which is identified on the late prophase chromosome in Figure 10.5, and assume the entire region is deleted. Approximately how many genes will be lost as a result of the deletion?
Problem 6
Consider synapsis in prophase I of meiosis for two plant species that each carries 36 chromosomes. Species A is diploid and species B is triploid. What characteristics of homologous chromosome synapsis can be used to distinguish these two species?
Problem 7
From the following list, identify the types of chromosome changes you expect to show phenotypic consequences. duplication
Problem 7a
From the following list, identify the types of chromosome changes you expect to show phenotypic consequences.
Pericentric inversion
Problem 7b
From the following list, identify the types of chromosome changes you expect to show phenotypic consequences.
Interstitial deletion
Problem 7d
From the following list, identify the types of chromosome changes you expect to show phenotypic consequences.
Terminal deletion
Problem 7e
From the following list, identify the types of chromosome changes you expect to show phenotypic consequences.
Trisomy
Problem 7f
From the following list, identify the types of chromosome changes you expect to show phenotypic consequences.
Reciprocal balanced translocation
Problem 7g
From the following list, identify the types of chromosome changes you expect to show phenotypic consequences.
Paracentric inversion
Problem 7h
From the following list, identify the types of chromosome changes you expect to show phenotypic consequences.
Monosomy
Problem 7i
From the following list, identify the types of chromosome changes you expect to show phenotypic consequences.
Polyploidy
Problem 8a
If the haploid number for a plant species is 4, how many chromosomes are found in a member of the species that has one of the following characteristics? Explain your reasoning in each case.
Diploidy