PROBLE MS A ND DIS C U S S ION QU E S TIONS
Summary Points 1. Mendel’s work on pea plants established the principles of gene transmission from parents to offspring that form the foundation for the science of genetics. 2. Genes and chromosomes are the fundamental units in the chromosomal theory of inheritance. This theory explains that inherited traits are controlled by genes located on chromosomes and shows how the transmission of genetic information maintains genetic continuity from generation to generation. 3. Molecular genetics—based on the central dogma that DNA is a template for making RNA, which encodes the order of amino acids in proteins—explains the phenomena described by Mendelian genetics, referred to as transmission genetics. 4. Recombinant DNA technology, a far-reaching methodology used in molecular genetics, allows genes from one organism to be spliced into vectors and cloned, producing many copies of specific DNA sequences. 5. Biotechnology has revolutionized agriculture, the pharmaceutical industry, and medicine. It has made possible the mass
Problems and Discussion Questions 1. Describe Mendel’s conclusions about how traits are passed from generation to generation. 2. What is the chromosome theory of inheritance, and how is it related to Mendel’s findings? 3. Define genotype and phenotype, and describe how they are related. 4. What are alleles? Is it possible for more than two alleles of a gene to exist? 5. Contrast chromosomes and genes. 6. How is genetic information encoded in a DNA molecule? 7. Describe the central dogma of molecular genetics and how it serves as the basis of modern genetics. 8. How many different proteins, each composed of 5 amino acids, can be constructed using the 20 different amino acids found in proteins? 9. Outline the roles played by restriction enzymes and vectors in cloning DNA. 10. How has biotechnology changed agriculture in the United States? 11. DNA microarrays or DNA chips are commercially available diagnostic tools used to test for gene expression. How might such chips be applied in human medicine? 12. In what ways is the discipline called genomics similar to proteomics? How are they different? What is meant by the term bioinformatics? 13. Summarize the arguments for and against patenting genetically modified organisms. 14. We all carry 20,000 to 25,000 genes in our genome. So far, patents have been issued for more than 6000 of these genes. Do you think that companies or individuals should be able to patent human genes? Why or why not? 15. How have model organisms advanced our knowledge of genes that control human diseases?
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For activities, animations, and review quizzes, go to the study area at www.masteringgenetics.com production of medically important gene products. Genetic testing allows detection of individuals with genetic disorders and those at risk of having affected children, and gene therapy offers hope for the treatment of serious genetic disorders. 6. Genomics, proteomics, and bioinformatics are new fields derived from recombinant DNA technology. These fields combine genetics with information technology and allow scientists to explore genome sequences, the structure and function of genes, the protein set within cells, and the evolution of genomes. The Human Genome Project is one example of genomics. 7. The use of model organisms has advanced the understanding of genetic mechanisms and, coupled with recombinant DNA technology, has produced models of human genetic diseases. 8. The effects of genetic technology on society are profound, and the development of policy and legislation to deal with issues derived from the use of this technology is lagging behind the resulting innovations.
For instructor-assigned tutorials and problems, go to www.masteringgentics.com 16. If you knew that an untreatable devastating late-onset inherited disease runs in your family (in other words, a disease that does not appear until later in life) and you could be tested for it at the age of 20, would you want to know whether you will develop that disease? Would your answer be likely to change when you reach age 40? 17. The Age of Genetics was created by remarkable advances in the use of biotechnology to manipulate plant and animal genomes. Given that the world population has topped 6 billion and is expected to reach 9.2 billion by 2050, some scientists have proposed that only the worldwide introduction of genetically modified (GM) foods will increase crop yields enough to meet future nutritional demands. Pest resistance, herbicide, cold, drought, and salinity tolerance, along with increased nutrition, are seen as positive attributes of GM foods. However, others caution that unintended harm to other organisms, reduced effectiveness to pesticides, gene transfer to nontarget species, allergenicity, and as yet unknown effects on human health are potential concerns regarding GM foods. If you were in a position to control the introduction of a GM primary food product (rice, for example), what criteria would you establish before allowing such introduction? 18. The BIO (Biotechnology Industry Organization) meeting held in Philadelphia in June 2005 brought together worldwide leaders from the biotechnology and pharmaceutical industries. Concurrently, BioDemocracy 2005, a group composed of people seeking to highlight hazards from widespread applications of biotechnology, also met in Philadelphia. The benefits of biotechnology are outlined in your text. Predict some of the risks that were no doubt discussed at the BioDemocracy meeting.