 |  Biology, 6/e Author Dr. George B. Johnson,
Washington University
Author Dr. Peter H. Raven,
Missouri Botanical Gardens & Washington University
Contributor Dr. Susan Singer,
Carleton College
Contributor Dr. Jonathan Losos,
Washington University
Gene Technology
Answers to Review Questions|
Chapter 19 (p. 418)
1. Although the DNA molecule is cut across both strands, the ends are single-stranded and complementary ("sticky"): often able to bind to other segments of DNA.
2. Clones that do not contain vectors can be identified by exposing the clones to something from which the vectors confer some sort of protection, such as antibiotic resistance. If the clone doesn’t have the resistant vector, it will die when exposed to the antibiotic.
3. The probe in a Southern Blot is a strand of nucleic acid that has been irradiated (usually with 32P). The radioactive nucleic acid hybridizes with the desired genetic fragment in the blot, which is subsequently identified by its radioactivity.
4. The Ti plasmid is most commonly used, typically affecting broadleaf plants such as tomato, tobacco, and soybean. Using this technique, scientists have been able to confer herbicide, virus, and insect resistance into plants, greatly improving crop yields.
5. BST is a synthetic growth hormone administered to cows to increase milk production. It is a hormone that cows already manufacture normally, and has no effect on consumers of milk (or on any other part of the cow!).
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2002 McGraw-Hill Higher Education