Chapter 12

Which of the following would be considered a transgenic organism? a. a bacterium that has received genes via conjugation b. a human given a corrected human blood-clotting gene c. a fern grown in cell culture from a single fern root cell d. a rat with rabbit hemoglobin genes

The DNA profiles used as evidence in a murder trial look something like supermarket bar codes. The pattern of bars in a DNA profile shows a. the order of bases in a particular gene. b. the presence of various-sized fragments of DNA. c. the presence of dominant or recessive alleles for particular traits. d. the order of genes along particular chromosomes.

A paleontologist has recovered a tiny bit of organic material from the 400 -year-old preserved skin of an extinct dodo. She would like to compare DNA from the sample with DNA from living birds. Which of the following would be most useful for increasing the amount of DNA available for testing? a. restriction fragment analysis b. polymerase chain reaction c. molecular probe analysis d. electrophoresis

When a typical restriction enzyme cuts a DNA molecule, the cuts are uneven, giving the DNA fragments single-stranded ends. These ends are useful in recombinant DNA work because a. they enable a cell to recognize fragments produced by the enzyme. b. they serve as starting points for DNA replication. c. the fragments will bond to other fragments with complementary ends. d. they enable researchers to use the fragments as molecular probes.

Why does DNA profiling rely on comparing specific genetic markers rather than the entire genome?

Recombinant DNA techniques are used to custom-build bacteria for two main purposes: to obtain multiple copies of certain genes and to obtain useful proteins produced by certain genes. Give an example of each of these applications in medicine and agriculture.

A biologist isolated a gene from a human cell, inserted it into a plasmid, and inserted the plasmid into a bacterium. The bacterium made a new protein, but it was nothing like the protein normally produced in a human cell. Why? (Explain your answer.) a. The bacterium had undergone transformation. b. The gene did not have sticky ends. c. The human gene contained introns. d. The gene was not synthesized from scratch.

Explain how you might engineer \(E\). coli to produce human growth hormone (HGH) using the following: E. coli containing a plasmid, DNA carrying the gene for HGH, DNA ligase, a restriction enzyme, equipment for manipulating and growing bacteria, a method for extracting and purifying the hormone, and an appropriate DNA probe. (Assume that the human HGH gene lacks introns.)

Today, it is fairly easy to make transgenic plants and animals. What are some important safety and ethical issues raised by this use of recombinant DNA technology? What are some of the possible dangers of introducing genetically engineered organisms into the environment? What are some reasons for and against leaving decisions in these areas to scientists? lo business owners and executives? What are some reasons for and against more public involvement? How might these decisions affect you? How do you think these decisions should be made?

In the not-too-distant future, gene therapy may be an option for the treatment and cure of some inherited disorders. What do you think are the most serious ethical issues that must be dealt with before human gene therapy is used on a large scale? Why do you think these issues are important?

The possibility of extensive genetic testing raises questions about how personal genetic information should be used. For example, should employers or potential employers have access to such information? Why or why not? Should the information be available to insurance companies? Why or why not? Is there any reason for the government to keep genetic files? Is there any obligation to warn relatives who might share a defective gene? Might some people avoid being tested for fear of being labeled genetic outcasts? Or might they be compelled to be tested against their wishes? Can you think of other reasons to proceed with caution?

Scientists investigate hypotheses using a variety of methods, depending on the circumstances behind the research. Human nutrition studies (such as those studying whether GMO foods have any health effects) are particularly problematic. Can you design a hypothetical human nutrition study to test whether GMO corn is less healthy than traditional corn? Can you identify real- world problems that may interfere with your design and confound your results?