CHAPTER 12 DNA Technology and the Human Genome

1. CHAPTER 12DNA Technology and the Human Genome Modules 12.15 – 12.21

2. THE CHALLENGE OF THE HUMAN GENOME 12.13 Most of the human genome does not consist of genes • The 23 chromosomes in the haploid human genome contain about 3 billion nucleotide pairs • This DNA is believed to include about 35,000 genes and a huge amount of noncoding DNA

3. Much of the noncoding DNA consists of repetitive nucleotide sequences • One example includes telomeres at the end of the chromosomes Repeated unit End ofDNAmolecule NUCLEOTIDE SEQUENCE OF A HUMAN TELOMERE Figure 12.13A

4. Barbara McClintock discovered that segments of DNA called transposons can move about within a cell’s genome Figure 12.13B, C

5. 12.14 Connection: The Human Genome Project is unlocking the secrets of our genes • The Human Genome Project involves: • genetic and physical mapping of chromosomes • DNA sequencing • comparison of human genes with those of other species Figure 12.14

6. OTHER APPLICATIONS OF DNA TECHNOLOGY 12.15 Connection: DNA technology is used in courts of law • DNA fingerprinting can help solve crimes Defendant’sblood Blood fromdefendant’sclothes Victim’sblood Figure 12.15A, B

7. 12.16 Connection: Recombinant cells and organisms can mass-produce gene products • Recombinant cells and organisms are used to manufacture useful proteins Table 12.16

8. These sheep carry a gene for a human blood protein that is a potential treatment for cystic fibrosis Figure 12.16

9. 12.17 Connection: DNA technology is changing the pharmaceutical industry and medicine • Hormones, cancer-fighting drugs, and new vaccines are being produced using DNA technology • This lab equipment is used to produce a vaccine against hepatitis B Figure 12.17

10. 12.18 Connection: Genetically modified organisms are transforming agriculture • New genetic varieties of animals and plants are being produced • A plant with a new trait can be created using the Ti plasmid

11. Agrobacteriumtumefaciens DNA containinggene for desired trait Plant cell 1 2 3 Tiplasmid RecombinantTi plasmid Insertion ofgene into plasmidusing restrictionenzyme and DNAligase Introductioninto plantcells inculture Regenerationof plant T DNA T DNAcarryingnew genewithin plantchromosome Plant withnew trait Restrictionsite Figure 12.18A

12. This rice could help prevent vitamin A deficiency • “Golden rice” has been genetically modified to contain beta-carotene Figure 12.18B

13. 12.19 Connection: Gene therapy may someday help treat a variety of diseases Cloned gene (normal allele) 1 Insertnormal geneinto virus • Techniques for manipulating DNA have potential for treating disease by altering an afflicted individual’s genes • Progress is slow, however • There are also ethical questions related to gene therapy Viral nucleicacid Retrovirus 2 Infect bonemarrow cellwith virus 3 Viral DNAinserts intochromosome Bone marrowcell from patient Bone marrow 4 Inject cellsinto patient Figure 12.19

14. RISKS AND ETHICAL QUESTIONS 12.20 Connection: Could GM organisms harm human health or the environment? • Genetic engineering involves some risks • Possible ecological damage from pollen transfer between GM and wild crops • Pollen from a transgenic variety of corn that contains a pesticide may stunt or kill monarch caterpillars Figure 12.20A, B

15. 12.21 Connection: DNA technology raises important ethical questions • Our new genetic knowledge will affect our lives in many ways • The deciphering of the human genome, in particular, raises profound ethical issues • Many scientists have counseled that we must use the information wisely Figure 12.21A-C