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Genes and DNA

Genes and DNA: A Beginner's Guide to Genetics and Its Applications

Copyright Date: 2004
Pages: 224
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  • Book Info
    Genes and DNA
    Book Description:

    Covering newsworthy aspects of contemporary biology -- gene therapy, the Human Genome Project, DNA testing, and genetic engineering -- as well as fundamental concepts, this book, written specifically for nonbiologists, discusses classical and molecular genetics, quantitative and population genetics -- including cloning and genetic diseases -- and the many applications of genetics to the world around us, from genetically modified foods to genetic testing.

    With minimal technical terminology and jargon, Genes and DNA facilitates conceptual understanding. Eschewing the organization of traditional genetics texts, the authors have provided an organic progression of information: topics are introduced as needed, within a broader framework that makes them meaningful for nonbiologists. The book encourages the reader to think independently, always stressing scientific background and current facts.

    eISBN: 978-0-231-50357-0
    Subjects: Ecology & Evolutionary Biology, Biological Sciences

Table of Contents

  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-xii)
  3. Acknowledgments
    (pp. xiii-xiv)
  4. List of Contributors
    (pp. xv-xvi)
  5. Preface: Why Is Genetics Important?
    (pp. xvii-xx)
  6. CHAPTER 1. What Are Genes?
    (pp. 1-18)

    YOU MAY ALREADY KNOW THAT GENES are made of DNA (short for deoxyribonucleic acid). More interesting than knowing this is understanding how we know that DNA is the basis for heredity and understanding the importance of the structure of DNA for inheritance. You will see in this chapter that DNA and its structure are the keys to understanding inheritance.

    DNA has a fascinating history. The Swiss scientist Friedrich Miescher discovered DNA near the end of the nineteenth century. Miescher never knew that the substance he had isolated from sperm and pus (yes, pus!) would turn out to be so critical...

  7. CHAPTER 2. Inheritance of Single-Gene Traits
    (pp. 19-33)

    HUMANS HAVE TINKERED WITH PLANTS and animals since before the dawn of recorded history. For example, it is thought that dogs were domesticated from wild wolves about 15,000 years ago. All the crops we eat today, including wheat, rice, and corn, are the products of thousands of years of breeding for larger grains, edibility, flavor, and other desirable characteristics. In addition to the domestic dog, horses, cows, goats, and pigs were bred from their wild ancestors. Obviously, domestication was a great success, for we now have many varieties of these useful crops and animals suited for different parts of the...

  8. CHAPTER 3. Mendelian Traits in Humans
    (pp. 34-52)

    WE NOW KNOW THAT THE BEHAVIOR of simple traits, determined by single genes that have a dominant and a recessive form, can be understood using the Punnett square. Yet we saw that Carl Correns, one of the rediscoverers of Mendel’s work, realized that even in a same species of flowers that seemed to follow Mendel’s rules for some traits, not all traits exhibited this simple form of inheritance. Many geneticists wondered whether these simple rules applied at all to animals and to humans. We will see in this chapter that simple rules of Mendelian inheritance do indeed apply to humans....

  9. CHAPTER 4. From Genes to Phenotype
    (pp. 53-69)

    AS WE SAW IN CHAPTER 1, DNA is a very long, thin molecule. This molecule contains the genes that determine what an organism is and does. Since the only thing that varies among DNA molecules is the sequence of base pairs, not the sugar-phosphate backbone, the “program” encoded by DNA must reside in the order of base pairs. And indeed, it is helpful to think of DNA as an old-fashioned ribbon-like computer tape (now replaced by CDs) containing the software of the cell, this software being the base sequence. As in any computer, the software can only be executed if...

  10. CHAPTER 5. Using Bacteria as Protein Factories
    (pp. 70-78)

    WE SAW IN CHAPTER 4 that the genetic code is universal; that is, codons are the same in all living organisms. This means that genes from one type of organism, animal cells for example, should be able to guide the synthesis of the corresponding protein in bacterial cells. In order to accomplish this, genes from one organism must be transferred to bacteria. We already saw in chapter 1 that DNA from one strain of bacteria can be transferred to another. This process is called bacterial transformation. Since DNA from different organisms has the same basic structure, only differing in the...

  11. CHAPTER 6. Genetically Modified Plants
    (pp. 79-92)

    YOU MAY HAVE HEARD ABOUT CONTROVERSIES surrounding genetically modified plants. These controversies have even caused street demonstrations and riots in several countries. You may also be assured that genetically modified food plants or their products find their way, on a daily basis, onto your breakfast, lunch, or dinner plates. Thus, it is important to understand what genetically modified plants are and how they are made. This scientific knowledge will allow you to form an informed opinion about the use of genetically modified plants.

    The words “genetically modified” constitute a serious misnomer. Humans have bred plants and animals for thousands of...

  12. CHAPTER 7. When Things Go Wrong
    (pp. 93-103)

    SO FAR, WE HAVE LEARNED THAT GENES RESIDE on chromosomes as sequences of DNA base pairs. When an organism develops from a single fertilized egg, each time a cell divides, the DNA is faithfully copied (chapter 1) and the billions of base pairs that are organized into chromosomes are divided equally between daughter cells in a process called mitosis (chapter 2). When we pass our genes to our offspring, DNA in specialized cells (gametes) is faithfully copied again, but these cells divide twice in a process called meiosis (chapter 2). This process is necessary in order to halve the genetic...

  13. CHAPTER 8. Mutagens, Teratogens, and Human Reproduction
    (pp. 104-113)

    IN CHAPTER 7 WE LEARNED that things can go wrong in the process of passing our genetic information to our offspring. So why do things go wrong? Is there something we can do to prevent mutations? In this chapter we will learn about different reasons for error in passing on our genetic information. We will also learn that nongenetic causes can cause problems in our offspring.

    DNA polymerase replicates DNA by making complementary copies of each of the double strands. If done perfectly, this process produces exact copies of the original double-stranded DNA. However, nothing is perfect. Consider that we...

  14. CHAPTER 9. Linkage and Mapping: Gene Discovery
    (pp. 114-137)

    AS WAS DISCUSSED IN CHAPTERS 5 AND 6 and will later be talked about in chapter 13, bacteria, plants, and animals have been genetically modified. This means that donor genes first had to be identified. Also, to properly diagnose diseases, it is necessary to pinpoint the defective gene. Identifying defective genes may then help with conventional therapy, as well as gene therapy. In order to accomplish these goals, genes first must be located, that is, their location on chromosomes be determined and their sequences deciphered.

    We now know that higher organisms contain many thousands of genes. For example, the fruit...

  15. CHAPTER 10. Genetics of Populations and Genetic Testing
    (pp. 138-152)

    SO FAR, WE HAVE DEALT WITH THE INHERITANCE of genes in single individuals. The genetic study of a collection of individuals must take into account variations in the population and reasons for those variations. The word “population” simply refers to large numbers of individuals able to breed: for example, human populations. The genetics of whole populations is useful for predicting the chances of genetic diseases occurring in large groups of individuals. It is also the basis for understanding differences in the frequency of traits or diseases in different ethnic groups.

    In chapter 3 we saw that the laws of Mendelian...

  16. CHAPTER 11. Survival of the Fittest?
    (pp. 153-174)

    IN CHAPTER 10, WE SAW that gene and genotype frequencies can vary considerably between different ethnic groups. In this chapter we will explore the underlying reasons for those differences. We will also see that our human activities can effect changes in the gene frequencies of other organisms, from bacteria to insects and other animals. More importantly, many of those changes in turn affect us.

    The phrase “survival of the fittest” may conjure up an image of a big strong lion with his pride of lionesses producing many lion cubs. In that example, the genes of the strong lion, as well...

  17. CHAPTER 12. Nature Versus Nurture
    (pp. 175-186)

    SO FAR WE HAVE SEEN THAT MENDELIAN TRAITS are categorized into discrete classes. That is, the different phenotypic classes that result from a cross can be sharply distinguished from one another, whether they are the colors of flowers or disease traits in humans. We also mentioned that many traits of economic and medical importance do not fall into discrete categories with sharply distinguishable phenotypes. These include the yields of most crops and farm animals and many common diseases like heart disease and diabetes. You may recall that Correns, one of the rediscovers of Mendel’s laws, mentioned that even with plants...

  18. CHAPTER 13. Genetically Modified Animals and the Applications of Gene Technology for Humans
    (pp. 187-198)

    GENETICALLY MODIFIED PLANTS are now widely available to consumers, as discussed in chapter 6, and, as we have also seen, generate a significant amount of controversy. Yet genetically modifying plants may seem to many people to be much less controversial than tampering with the genetic blueprint of animals. This is due in part to our own view of animals. Indeed, for most people it is easier to relate to a dog, a goat, or even a mouse than it is to relate to a banana or a corn plant. What’s more, the genetic engineering of animals immediately brings to mind...

  19. APPENDIX A. Internet Resources
    (pp. 199-202)
  20. APPENDIX B. Glossary of Scientific Names of Organisms
    (pp. 203-204)
  21. APPENDIX C. Glossary of Human Genetic Diseases
    (pp. 205-206)
  22. APPENDIX D. Glossary of Terms
    (pp. 207-212)
  23. Index
    (pp. 213-218)