Understanding Genetics: DNA, Genes, and Their Real-World Applications Parts I & II Professor David Sadava THE TEACHING COMPANY ® Table of Contents Understanding Genetics: DNA, Genes, and Their Real-World Applications Professor Biography..............................................................................................................................................iii Course Scope...........................................................................................................................................................1 Lecture One Our Inheritance...................................................................................................................................2 Lecture Two Mendel and Genes..............................................................................................................................4 Lecture Three Genes and Chromosomes................................................................................................................7 Lecture Four The Search for the Gene—DNA.......................................................................................................9 Lecture Five DNA Structure and Replication.......................................................................................................12 Lecture Six DNA Expression in Proteins..............................................................................................................14 Lecture Seven Genes, Enzymes, and Metabolism.................................................................................................17 Lecture Eight From DNA to Protein.....................................................................................................................19 Lecture Nine Genomes..........................................................................................................................................22 Lecture Ten Manipulating Genes—Recombinant DNA.......................................................................................25 Lecture Eleven Isolating Genes and DNA............................................................................................................28 Lecture Twelve Biotechnology—Genetic Engineering........................................................................................31 Lecture Thirteen Biotechnology and the Environment.......................................................................................34 Lecture Fourteen Manipulating DNA by PCR and Other Methods....................................................................37 Lecture Fifteen DNA in Identification—Forensics..............................................................................................40 Lecture Sixteen DNA and Evolution....................................................................................................................43 Lecture Seventeen DNA and Human Evolution..................................................................................................46 Lecture Eighteen Molecular Medicine—Genetic Screening...............................................................................49 Lecture Nineteen Molecular Medicine—The Immune System...........................................................................53 Lecture Twenty Molecular Medicine—Cancer...................................................................................................55 Lecture Twenty-One Molecular Medicine—Gene Therapy...............................................................................58 Lecture Twenty-Two Molecular Medicine—Cloning and Stem Cells................................................................61 Lecture Twenty-Three Genetics and Agriculture...............................................................................................64 Lecture Twenty-Four Biotechnology and Agriculture.......................................................................................68 Timeline................................................................................................................................................................71 Glossary................................................................................................................................................................75 Biographical Notes...............................................................................................................................................81 Bibliography.........................................................................................................................................................85 David Sadava, Ph.D. Pritzker Family Foundation Professor of Biology The Claremont McKenna, Pitzer, and Scripps Colleges David Sadava is the Pritzker Family Foundation Professor of Biology at Claremont McKenna, Pitzer, and Scripps, three of The Claremont Colleges. Professor Sadava graduated from Carleton University as the science medalist, with a B.S. with first-class honors in Biology and Chemistry. A Woodrow Wilson Fellow, he received a Ph.D. in Biology from the University of California at San Diego. Following postdoctoral research at the Scripps Institution of Oceanography, he joined the faculty at Claremont, where he has twice won the Huntoon Award for Superior Teaching, as well as receiving numerous other faculty honors. He teaches undergraduate courses in general biology, biotechnology, and cancer biology, and has been a visiting professor at the University of Colorado and at the California Institute of Technology. A visiting scientist in oncology at the City of Hope Medical Center, Professor Sadava has held numerous research grants and written more than 55 peer-reviewed scientific research papers, many with his undergraduate students as coauthors. His research concerns resistance to chemotherapy in human lung cancer, with a view to developing new, plant-based medicines to treat this disease. He is the author or coauthor of five books, including Plants, Genes, and Crop Biotechnology and the recently published eighth edition of a leading biology textbook, Life: The Science of Biology. Understanding Genetics: DNA, Genes, and Their Real-World Applications Scope: Perhaps no branch of knowledge has been as exciting over the past 50 years as genetics, the scientific study of heredity. The DNA double helix, discovered in 1953, is one of the great icons of science in our society, rivaling the atom in its pervasiveness in our culture. Like the atom, DNA symbolizes not just scientific knowledge that in this case doubles every few years, but immense implications for humanity. Knowledge of DNA and genetics is radically impacting the two important applications of biology to human welfare—medicine and agriculture. In addition, studies of genes are changing the way we look at ourselves and the other organisms with which we share the Earth. Lectures One through Three describe genetics as we knew it before DNA. People have long wondered how characteristics are passed on through generations. Before the mechanism of inheritance was investigated with the methods of experimental science, there were many ideas. Some scientists and philosophers thought that only the male (or female) contributed inheritance to offspring. Others proposed that, while the sexes contributed equally to the offspring, whatever it was that each contributed blended together permanently after the union of male and female. The Austrian monk and scientist Gregor Mendel put an end to these notions in 1866 when he published the results and interpretation of years of deliberate and careful experiments on pea plants. He clearly showed not only that the sexes contribute equally to offspring, but also that the genetic determinants, or genes, were particulate and retained their individuality after mating. Almost 40 years later, his results and conclusions were independently verified by other scientists. As biologists began to study life at the microscopic level, in the tiny cells that make up every organism, the genes were located in structures inside of every cell called chromosomes. Mendel and his successors, and the cell biologists looking at chromosomes, gave geneticists the tools to work out the rules of inheritance. But the exact nature of what determined inherited characteristics remained unknown. The nature of genes and how they are arranged and expressed is described in Lectures Four through Nine. The search for what the gene really is made of quickly focused on DNA. Circumstantial evidence favored it: DNA was in the right place at the right times in the right amounts. But these were correlations—and as such are not valid scientific evidence. A set of experiments on many different organisms provided the proof that DNA was the molecule of heredity. Soon afterward, the double-helix model of DNA was described, as was the elegant way in which it duplicates itself when cells reproduce. The next issue was to determine how DNA as the gene is expressed. The information in each gene is usually expressed as a protein. These complex molecules have vital roles in the organism. They provide structure and can act as enzymes to speed up chemical transformations inside cells. With thousands of such proteins, there are thousands of genes. Coming full circle, the gene-protein relationship was described in a genetic code that is virtually universal in all life on Earth. By the end of the 20th century, biologists were able to determine the information content of every gene of an organism (the genome)