A PERSPECTIVE ON HUMAN GENETICS

A Perspective on Human Genetics

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A PERSPECTIVE ON HUMAN GENETICS

CHAPTER OUTLINE

GENETICS AND TRANSLATIONAL

MEDICINE

GENETICS IS THE KEY TO BIOLOGY

WHAT ARE GENES AND HOW DO THEY

WORK?EXPLORING GENETICS —Genetic Disorders in Culture and Art

HOW ARE GENES TRANSMITTED FROM

PARENTS TO OFFSPRING?

HOW DO SCIENTISTS STUDY GENES?

Some basic methods in genetics.Genetics is used in basic and applied research.

HAS GENETICS AFFECTED SOCIAL

POLICY AND LAW?

The misuse of genetics has affected social policy.Eugenics was used to pass restrictive immigration laws in the U.S.Eugenics was used to restrict reproductive rights.The decline of eugenics in the U.S.began with the rise of the Nazi movement.

WHAT IMPACT IS GENOMI CS HAVING?

Identifying and using genetic variation in genomics.Health care uses genetic testing and genome scanning.Stem cell research offers hope for treating many diseases.Biotechnology is impacting everyday life.

WHAT CHOICES DO WE MAKE IN THE

ERA OF GENOMICS AND

BIOTECHNOLOGY?

CHAPTER SUMMARY

Chapter 1 introduces the student to genetics, the science of heredity. The first part emphasizes that heredity can be studied at many levels and that there are several different branches of genetics, which are defined and described. The DNA molecule is described, and the basic way in which genes work is presented.

Mendel’s historical insight about how genes are transmitted from parent to offspring is summarized. Then transmission genetics (including pedigree analysis, the basic tool of human geneticists), cytogenetics, molecular genetics, and population genetics are described. Basic research, as distinguished from applied research, and some of the benefits and controversial developments of applied research are introduced.

The last part of the chapter highlights the impact human genetics has on our lives. Many of the applications of genetic knowledge possess political, legal, and ethical implications, which the (Human Heredity Principles and Issues, 11e Michael Cummings) (Instructor Manual) 1 / 4

Chapter One

readers are encouraged to examine. This begins with an account of the eugenics movement and how it has affected our laws and social policies. It continues with an outline of how recombinant DNA technology and genomics are changing our lives. Specifically, it describes how knowledge of the human genome, stem cell research, and biotechnology are revolutionizing health care and agriculture. It ends with examples of some of the challenging practical and ethical choices we face in the new era of biotechnology.

The chapter’s emphasis on ethical and social issues is taken up by two “Genetics and Society” sections on genetic disorders in culture and art, and eugenics in Nazi Germany, respectively.

TEACHING/LEARNING OBJECTIVES

At the completion of this chapter, the student should be able to:

1-1 Genetics and Translational Medicine 1-1-1: Explain the connection between genetic research and clinical medicine as it relates to cancer treatment.1-2 Genetics Is the Key to Biology 1-2-1: Define the term genetics and summarize its role in our understanding of all of biology.1-3 What Are Genes and How Do They Work?1-3-1: Identify basic gene components and diagram the structure of a DNA molecule.

1-3-2: Describe the role of genes in the production of proteins.

1-4 How Are Genes Transmitted from Parents to Offspring?

1-4-1: Discuss Gregor Mendel and his role in the early science of genetics.

1-4-2: Explain how Mendel’s research with pea plants has increased our understanding of how specific traits are passed from parent to offspring by genes.1-5 How Do Scientists Study Genes?1-5-1: Compare and contrast the different methods scientists use to study genetics.1-5-2: Differentiate between basic and applied research and illustrate how each approach is used in the study of genetics.1-6 Has Genetics Affected Social Policy and Law?

1-6-1: Explain the field of eugenics as proposed by Francis Galton.

1-6-2: Assess the social and political ramifications of eugenics policies.

1-6-3: Summarize the flaws in eugenics theory and critique its influence in the U.S. during the early 20 th century.1-7 What Impact Is Genomics Having?1-7-1: Describe genome sequencing and illustrate various methods of use in the treatment of disease, genetic testing, and plant and animal modification.1-8 What Choices Do We Make in the Era of Genomics and Biotechnology?1-8-1: Debate the ethical and social issues that the use of genomics and biotechnology introduces to society.

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A Perspective on Human Genetics

TERMS DEFINED IN THIS CHAPTER

• Translational Medicine: The union of research and medicine that seeks to quickly translate research findings into methods for the diagnosis and treatment of diseases.• Immunotherapy: A method for treating diseases by stimulating or enhancing an immune response.

• Genetics: The scientific study of heredity.

• Trait: Any observable property of an organism.

• Gene: The fundamental unit of heredity and the basic structural and functional unit of genetics.• DNA: A helical molecule consisting of two strands of nucleotides that is the primary carrier of genetic information.• Transmission genetics: The branch of genetics concerned with the mechanisms by which genes are transferred from parent to offspring.• Pedigree analysis: The construction of family trees and their use to follow the transmission of genetic traits in families. It is the basic method of studying the inheritance of traits in humans.• Cytogenetics: The branch of genetics that studies the organization and arrangement of genes and chromosomes using the techniques of microscopy.• Karyotype: A complete set of chromosomes from a cell that has been photographed during cell division and arranged in a standard sequence.

• Molecular genetics: The study of genetic events at the biochemical level.

• Recombinant DNA technology: A series of techniques in which DNA fragments are linked to self-replicating vectors to create recombinant DNA molecules, which are replicated in a host cell.• Clones: Genetically identical molecules, cells, or organisms all derived from a single ancestor.• Gene therapy: Procedure in which normal genes are transplanted into humans carrying defective copies as a means of treating genetic diseases.

• Genome: The set of genetic information carried in the DNA of an individual.

• Genomics: The study of the organization, function, and evolution of genomes.• Population genetics: The branch of genetics that studies inherited variation in populations of individuals and the forces that alter gene frequency.

• Eugenics: The attempt to improve the human species by selective breeding.

• Hereditarianism: The idea that human traits are determined solely by genetic inheritance, ignoring the contribution of the environment. 3 / 4

Chapter One

• Single nucleotide polymorphism (SNP): Single nucleotide differences between and among individuals in a population or species.• Haplotype: A set of genetic markers located close together on a single chromosome or chromosome region.• Genome-wide association study (GWAS): Analysis of genetic variation across an entire genome searching for association between variations and a genome region encoding a specific phenotype.• Biotechnology: The use of recombinant DNA technology to produce commercial goods and services.

TEACHING HINTS

Since this is an introductory chapter, many concepts and terms are introduced but not explained at any length. Encourage students to do active reading of this chapter by writing down any questions that come to their minds. Perhaps give them a specific assignment to write four or five such questions for class discussion. The class discussion can then be used to answer questions and/or point out that some questions will be answered in detail in coming parts of the course. This helps students to develop an overall sense of the course content and to anticipate some of what is to come, and this is one purpose of Chapter 1.

The one major topic of Chapter 1 not significantly developed in later chapters is eugenics.Students usually show great interest in this topic and can easily be horrified by the accounts of its misuse in both Nazi Germany and the U.S. Three good, provocative questions for them to get beyond mere horror are: (1) Can genetics ever be a valid reason for restrictive immigration policies? (2) Are there any circumstances in which compulsory sterilization can be justified? and (3) Are there genetic technologies in use today or ones that will be available in the near future that could be considered as promoting eugenics?

VIDEOS, WEBSITES, AND ANIMATIONS

VIDEOS

TED Talks — Barry Schuler Genomics 101 The former CEO of AOL talks about the ramifications of genomic research.

http://www.ted.com/talks/barry_schuler_genomics_101.html

TED Talks — James Watson The co-discoverer of the structure of DNA on how it was discovered.

http://www.ted.com/talks/james_watson_on_how_he_discovered_dna.html

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