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​Chapter 6 Instructor Resources​

People Improving Plants: Genes and Genetic Engineering

Deoxyribonucleic acid (DNA) contains the genetic code. This code must be translated into proteins that run the cellular reactions that allow organisms to grow and reproduce. Today we know the genetic code of many different organisms. Specific genes can be identified and transferred to other organisms. Genes that confer disease resistance, improved nutrition, salt tolerance, and many other agricultural benefits can be incorporated through both traditional breeding and genetic engineering. The plant-pathogenic bacterium Agrobacterium tumefaciens is widely used to transfer beneficial genes into plants.

• Chapter 5 Podcast

  Chapter 5 Podcast

  Listen to the Podcast (mp3)
  

  The short podcast provided for each chapter includes a review of a major concept or issue, clarification of an important point that can be confusing to students, and questions for students to think about. This podcast discusses three processes used throughout history to create transgenic plants and describes the central dogma of biology.

• Short Writing Assignment

  Notes: This assignment requires each student to write a paragraph (introductory sentence, body, concluding sentence) and can be completed in 10–15 minutes in class. It provides a good way to check student comprehension and to improve student writing skills. See Chapter 1 for a simple grading system.

  
  

  Genetic Engineering Opinion Statement

  You have now learned about the basics of genetics, the breeding of plants for disease resistance, and the processes involved in modifying plants using traditional breeding and genetic engineering techniques. Describe how this information has changed or reinforced your opinion on the appropriateness of developing and using genetically modified crop plants. Provide specific examples where possible, and integrate at least two pieces of factual information that support or contradict your opinion.

  
  
• Longer Writing Assignments

  1) Genetic Engineering Paper

  For this paper on genetic engineering, complete both parts a and b:

  1. Briefly describe how genetic engineering is accomplished in plants.
  2. Choose one of these topics:
  • Current use of the label “organic” means that genetically engineered products are not included. What is your opinion on whether this label is sufficient for consumers who do not want to buy genetically engineered foods? Should all genetically engineered foods be labeled? Use scientific information to support your opinion. If you favor a label, consider what it should tell consumers that will help them make informed purchasing decisions. For example, should a label be required if a gene from a wild relative of the plant has been added? Should a food be labeled if that same gene is added through standard cross-breeding?
    OR
    
  • Describe one application of genetic engineering technology that you strongly support or that you believe should not be done. Explain your position, and use scientific information to support it.
  
  

  Note: Do not use these arguments:

  • It isn't natural
  • We shouldn't "mess with mother nature"
  
  

  
  

  2) The Environmental Impact of Genetically Modified Crops

  Each year, more countries approve the planting of genetically engineered (GE) crops, and the worldwide acreage planted with these crops increases. GE crops have provided benefits to both producers and consumers, but many people remain concerned about them. One significant area of concern is the long-term environmental effects of GE crops. Both positive and negative environmental effects have been proposed and, to a lesser degree, documented.

  What are the current and potential environmental benefits and risks of GE crops? Can the risks be managed so that they are acceptable? Do the current and potential benefits outweigh the current and potential risks? Write a short essay (~ 350 words) on this topic.

  Here are some questions to consider:

  • What is genetic engineering?
  • How is a GE plant developed?
  • What are the sources of the “new” genes in GE crops?
  • How many GE crops are currently grown? Where?
  • What are the documented environmental benefits of GE crops?
  • Can these benefits be achieved with non-GE crops?
  • What are the documented environmental risks of GE crops?
  • Are these risks limited to GE crops?

  
  

  Notes:

  • You can make the audience for the assignment someone other than yourself—for example, a local farmer who is considering planting a GE crop or the editor of a local newspaper. The selected audience should dictate the style of writing students use.
  • Opinion papers such as this can be written in several drafts: Draft 1 (evaluated but not graded) summarizes the facts; draft 2 (also evaluated but not graded) incorporates the student’s opinion, supported by the facts; and draft 3 is a polished version of draft 2, which is finally graded. Students appreciate the opportunity to get feedback on their writing and thinking before being assigned a grade. This system also provides an opportunity for students to learn to separate facts from opinions and to evaluate the biases of different sources of information.
  • You can provide students with a reference list (including links), so that this is an exercise in evaluating and using information, rather than finding it. Extra credit can be given for sources with new information that students find and use in their papers.

  
  

  Evaluation of Paper:

  Criteria used in evaluation can include the following:

  • Accuracy and completeness of factual information
  • Development and support of opinion
  • Overall organization and clarity
  • Mechanics (e.g., spelling, grammar, sentence structure)
  • Use of supporting references

  
  

  Important Note: This paper has no “right” or “wrong” conclusion. The student can take either side of the issue (pro-GE or anti-GE), include the pertinent facts, and use them to support his or her position.

  
  
• Group Discussions

  1) Genetics and Genetic Engirneering Terminology

  Break the class into small groups of 3–5 people, and ask each group to complete the crossword puzzle. All of the answers are vocabulary words used in the class(es) on genetics and genetic engineering of plants.

  Note: The three "i" words are identify, isolate, and insert

  
  

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  Across

  1. The assembling of amino acids into a protein using messenger RNA, ribosomes, and transfer RNA

  3. A circular, self-replicating hereditary element that is not part of a chromosome; used in recombinant DNA

  experiments as an acceptor and vector of foreign DNA

  4. The third “i” in genetic modification

  6. The production of a complementary strand of RNA from a segment of DNA

  9. A soilborne bacterium used in genetic modification

  10. The double-stranded, helical molecule that contains genetic code information

  12. Genetic constitution of an individual or group; a class or group of individuals sharing a specific genetic makeup

  13. External, visible physical characteristics of an organism determined by the interaction of its genotype with the environment

  15. The second “i” in genetic modification

  16. Transcribed from DNA and involved in translation to proteins

  17. Describes a phenotypic trait that is expressed in diploid organisms only if both parents contribute the trait to the progeny

  18. The structure that contains the genes of an organism

  
  

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  Down

  1. The concept that even specialized cells contain all of the genetic information for an organism and, therefore, that any cell should be able to regenerate into any tissue or into an entire plant

  2. A type of enzyme that cleaves DNA at a particular base sequence

  4. The first “i” in genetic modification

  5. The units within an organism that control heritable characteristics; the units are organized on chromosomes

  7. A nitrogen-containing organic compound composed of units called amino acids

  8. Describes a phenotypic trait that is expressed in hybrid progeny of diploid organisms even when contributed by only one of the parents

  11. The process by which a DNA molecule makes an exact copy of itself

  14. Any of one or more alternative forms of a gene

  
  
  

  After giving small groups 10–15 minutes to complete the puzzle, have the whole class fill it in with contributions from different groups. Review the meanings of the terms and their roles in the genetic engineering of plants.

  
  

  2) Transgenic Plants

  1. Is the term GMO (genetically modified organism) appropriate for genetically engineered organisms? Suggest a more appropriate term.
  2. Consider some of the following applications of genetic engineering:
  • Beneficial genes from wild relatives to crop plants
  • Bt (bacillus thuringiensis) toxin genes to protect crops from insects
  • Glyphosate-resistance genes to crop plants (Roundup Ready crops)
  • Plant virus genes into plant genomes for virus resistance
  • Salt-tolerance genes so crops can be watered with brackish (somewhat salty) water
  • Genes that are precursors of vitamin A into rice (“golden rice”) to help prevent blindness in Asian
  countries or other genes that improve plant nutrient levels

  
  

  Which of these applications sound acceptable to you, and which make you uneasy? Why?

  Organize your concerns into these three categories:

  
  

  Economic	Environmental	Food Safety
  ​

  
  

  Note: Many of the topics related to genetic engineering are interesting topics for class discussions and student papers. Among them are social/ethical aspects of companies patenting genes, rights of farmers to save seed, and transfer of GM traits to surrounding crops through pollen—a particular problem for organic crops.