18. Molecular Genetic Tools

Methods for Analyzing DNA

Open Question
In an inheritance case, a man has died leaving his estate to be divided equally between 'his wife and his offspring.' His wife (M) has an adult daughter (D), and they argue that they should split the estate equally. As a young couple, however, the man and his wife had a son that they gave up for adoption. Two men have appeared, each claiming to be the son of the couple and therefore entitled to a one-third share of the estate. The accompanying illustration shows the results of DNA analysis for five genes for the mother (M), her daughter (D), and the two claimants (S1 and S2).Do the DNA results suggest that either man is likely to be the son of the man and his wife? Explain.
Open Question
In Drosophila, loss-of-function Ultrabithorax mutations result in the posterior thoracic segments differentiating into body parts with an identity normally found in the anterior thoracic segments. When the Ultrabithorax gene was cloned, it was shown to encode a transcription factor and to be expressed only in the posterior region of the thorax. Thus, Ultrabithorax acts to specify the identity of the posterior thoracic segments. Similar genes were soon discovered in other animals, including mice and humans. You have found that mice possess two closely related genes, Hoxa7 and Hoxb4, which are orthologs (see Genetic Analysis 14.2 for definition) of Ultrabithorax. You wish to know whether the two mouse genes act to specify the identity of body segments in mice.How will you determine where and when the mouse genes are expressed?
Multiple Choice
In terms of molecular biology, what is a library?
Multiple Choice
If you had a sample of RNA to analyze, which of the following techniques would you most likely use?
Open Question
What is CODIS? Describe the four most important features of genetic markers used in this system.
Open Question
In this chapter, we focused on a number of interesting applications of genetic engineering, genomics, and biotechnology. At the same time, 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?From GWAS how do we know which genes are associated with a particular genetic disorder?
Open Question
In this chapter, we focused on a number of interesting applications of genetic engineering, genomics, and biotechnology. At the same time, 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?

How does a positive ASO test for sickle-cell anemia determine that an individual is homozygous recessive for the mutation that causes sickle-cell anemia?
Open Question
Compare and contrast the terms Paternity Index (PI) and Combined Paternity Index (CPI). How does each contribute to paternity determination?
Open Question
What is the exclusion principle? How is it used in forensic genetic analysis and in paternity determination?
Open Question
What is the statistical principle underlying genetic health risk assessment? Why are these assessments not predictive of disease occurrence?
Open Question
You have constructed four different libraries: a genomic library made from DNA isolated from human brain tissue, a genomic library made from DNA isolated from human muscle tissue, a human brain cDNA library, and a human muscle cDNA library.Which of these would have the greatest diversity of sequences?
Open Question
You have constructed four different libraries: a genomic library made from DNA isolated from human brain tissue, a genomic library made from DNA isolated from human muscle tissue, a human brain cDNA library, and a human muscle cDNA library.Would the sequences contained in each library be expected to overlap completely, partially, or not at all with the sequences present in each of the other libraries?
Open Question
Using the genomic libraries in Problem 4, you wish to clone the human gene encoding myostatin, which is expressed only in muscle cells.Assuming the human genome is 3x10⁹ and that the average insert size in the genomic libraries is 100 kb, how frequently will a clone representing myostatin be found in the genomic library made from muscle?
Open Question
Explain the meaning of 'identity by descent' in the context of identifying genealogical relationship between individuals. In these analyses, why are segments of chromosomes (haplotypes) rather than individual STRs used to identify genetic relationships?
Open Question
Using the genomic libraries in Problem 4, you wish to clone the human gene encoding myostatin, which is expressed only in muscle cells.How frequently will a clone representing myostatin be found in the genomic library made from brain?