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Problem 1
In this chapter we focused on how specific DNA sequences can be copied, identified, characterized, and sequenced. At the same time, we found many opportunities to consider the methods and reasoning underlying these techniques. From the explanations given in the chapter, what answers would you propose to the following fundamental questions?
In a recombinant DNA cloning experiment, how can we determine whether DNA fragments of interest have been incorporated into plasmids and, once host cells are transformed, which cells contain recombinant DNA?Problem 1
In this chapter we focused on how specific DNA sequences can be copied, identified, characterized, and sequenced. At the same time, we found many opportunities to consider the methods and reasoning underlying these techniques. From the explanations given in the chapter, what answers would you propose to the following fundamental questions?
What steps make PCR a chain reaction that can produce millions of copies of a specific DNA molecule in a matter of hours without using host cells?Problem 1
In this chapter we focused on how specific DNA sequences can be copied, identified, characterized, and sequenced. At the same time, we found many opportunities to consider the methods and reasoning underlying these techniques. From the explanations given in the chapter, what answers would you propose to the following fundamental questions?
How has DNA-sequencing technology evolved in response to the emerging needs of genome scientists?Problem 1
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?Problem 1
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?
What experimental evidence confirms that we have introduced a useful gene into a transgenic organism and that it performs as we anticipate?- In this chapter we focused on how specific DNA sequences can be copied, identified, characterized, and sequenced. At the same time, we found many opportunities to consider the methods and reasoning underlying these techniques. From the explanations given in the chapter, what answers would you propose to the following fundamental questions? How can gene knockouts, transgenic animals, and gene editing techniques be used to explore gene function?
Problem 1
- 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?
Problem 1
Problem 2
Write a short essay that summarizes the impacts that genomic applications are having on society and discuss which of the ethical issues presented by these applications is the most daunting to society.
Problem 2
Write a short essay or sketch a diagram that provides an overview of how recombinant DNA techniques help geneticists study genes.
Problem 3
Why are most recombinant human proteins produced in animal or plant hosts instead of bacterial host cells?
Problem 3
What roles do restriction enzymes, vectors, and host cells play in recombinant DNA studies? What role does DNA ligase perform in a DNA cloning experiment? How does the action of DNA ligase differ from the function of restriction enzymes?
Problem 4
The human insulin gene contains a number of sequences that are removed in the processing of the mRNA transcript. In spite of the fact that bacterial cells cannot excise these sequences from mRNA transcripts, explain how a gene like this can be cloned into a bacterial cell and produce insulin.
- One of the major causes of sickness, death, and economic loss in the cattle industry is Mannheimia haemolytica, which causes bovine pasteurellosis, or shipping fever. Noninvasive delivery of a vaccine using transgenic plants expressing immunogens would reduce labor costs and trauma to livestock. An early step toward developing an edible vaccine is to determine whether an injected version of an antigen (usually a derivative of the pathogen) is capable of stimulating the development of antibodies in a test organism. The following table assesses the ability of a transgenic portion of a toxin (Lkt) of M. haemolytica to stimulate development of specific antibodies in rabbits. Immunogen Injected Antibody Production in Serum Lkt50*—saline extract + Lkt50*—column extract + Mock injection - *Lkt50 is a smaller derivative of Lkt that lacks all hydrophobic regions. indicates at least 50 percent neutralization of toxicity of Lkt; indicates no neutralization activity. Source: Modified from Lee et al. (2001). Infect. and Immunity 69:5786–5793. What general conclusion can you draw from the data?
Problem 4
- One of the major causes of sickness, death, and economic loss in the cattle industry is Mannheimia haemolytica, which causes bovine pasteurellosis, or shipping fever. Noninvasive delivery of a vaccine using transgenic plants expressing immunogens would reduce labor costs and trauma to livestock. An early step toward developing an edible vaccine is to determine whether an injected version of an antigen (usually a derivative of the pathogen) is capable of stimulating the development of antibodies in a test organism. The following table assesses the ability of a transgenic portion of a toxin (Lkt) of M. haemolytica to stimulate development of specific antibodies in rabbits. Immunogen Injected Antibody Production in Serum Lkt50*—saline extract + Lkt50*—column extract + Mock injection - *Lkt50 is a smaller derivative of Lkt that lacks all hydrophobic regions. indicates at least 50 percent neutralization of toxicity of Lkt; indicates no neutralization activity. Source: Modified from Lee et al. (2001). Infect. and Immunity 69:5786–5793. With regards to development of a usable edible vaccine, what work remains to be done?
Problem 4
Problem 5
Although many cloning applications involve introducing recombinant DNA into bacterial host cells, many other cell types are also used as hosts for recombinant DNA. Why?
Problem 6
Using DNA sequencing on a cloned DNA segment, you recover the nucleotide sequence shown below. Does this segment contain a palindromic recognition sequence for a restriction enzyme? If so, what is the double-stranded sequence of the palindrome, and what enzyme would cut at this sequence? (Consult Figure 20.1 for a list of restriction sites.)
CAGTATGGATCCCATProblem 7
As genetic testing becomes widespread, medical records will contain the results of such testing. Who should have access to this information? Should employers, potential employers, or insurance companies be allowed to have this information? Would you favor or oppose having the government establish and maintain a central database containing the results of individuals' genome scans?
Problem 7
Restriction sites are palindromic; that is, they read the same in the 5' to 3' direction on each strand of DNA. What is the advantage of having restriction sites organized this way?
Problem 8
Might it make sense someday to sequence every newborn's genome at the time of birth? What are the potential advantages and concerns of this approach?
Problem 8
List the advantages and disadvantages of using plasmids as cloning vectors. What advantages do BACs and YACs provide over plasmids as cloning vectors?
Problem 9
Which of the examples of genetic testing below are prognostic tests? Which are diagnostic?
Genetic testing in a healthy teenager identifies an SNP correlated with autism.Problem 9
Which of the examples of genetic testing below are prognostic tests? Which are diagnostic?
An adult diagnosed with Asperger syndrome (AS) has a genetic test that reveals a SNP in the GABRB3 gene that is significantly more common in people with AS than the general population.Problem 9
Which of the examples of genetic testing below are prognostic tests? Which are diagnostic?
Individual sequencing (personal genomics) identifies a mutation associated with Alzheimer's disease.Problem 9
Which of the examples of genetic testing below are prognostic tests? Which are diagnostic?
ASO testing determines that an individual is a carrier for the mutant β-globin allele (βˢ) found in sickle-cell anemia.Problem 9
Which of the examples of genetic testing below are prognostic tests? Which are diagnostic?
DNA sequencing of a breast tumor reveals mutations in the BRCA1 gene.Problem 9
What are the advantages of using a restriction enzyme whose recognition site is relatively rare? When would you use such enzymes?
Problem 10
Does genetic analysis by ASO testing allow for detection of epigenetic changes that may contribute to a genetic disorder? Explain your answer.
Problem 10
In 1975, the Asilomar Conference on Recombinant DNA was organized by Paul Berg, a pioneer of recombinant DNA technology, at a conference center at Asilomar State Beach in California. Physicians, scientists, lawyers, ethicists, and others gathered to draft guidelines for safe applications of recombinant DNA technology. These general guidelines were adopted by the federal government and are still in practice today. Consider the implications of recombinant DNA as a new technology. What concerns might the scientific community have had then about recombinant DNA technology? Might those same concerns exist today?
- Outline the roles played by restriction enzymes and vectors in cloning DNA.
Problem 10
Problem 11
Maternal blood tests for three pregnant women revealed they would be having boys, yet subsequent ultrasound images showed all three were pregnant with girls. In each case Y chromosome sequences in each mother's blood originated from transplanted organs they had received from men! This demonstrates one dramatic example of a limitation of genetic analysis of maternal blood samples. What kind of information could have been collected from each mother in advance of these tests to better inform physicians prior to performing each test?
