Chapter 3 Human Genetics and Gene Expression

Overview

A nervous couple sits in the waiting room, anxiously anticipating the results of a test. Their last child had lived her short life in almost constant pain and had died, blind, at age three, a victim of Tay–Sachs disease. The couple wants another child, but their previous experience was a heart-wrenching nightmare that they don’t want to repeat. They are awaiting the results of an amniocentesis, a technique that you will read about later in this chapter. A doctor enters the room with good news: the enzyme that her technicians were testing for is present in the amniotic fluid. The mother-to-be is carrying a child who will not get Tay–Sachs disease. The couple can look forward to raising a healthy child in a happy home.

Scenes like the one just described are happening more often with each passing year. An increasing number of couples are undergoing medical procedures that did not exist when they themselves were born, seeking assurances that would have been unthinkable a mere 25 years ago. Tay–Sachs disease is one of a growing number of inherited conditions that can now be diagnosed before birth. This type of information can allow parents to make informed decisions about whether to consider terminating a pregnancy if the fetus has a severe condition that will not allow for a good quality or life or to prepare in advance for the care of a child with special needs.

Some traits follow the simple Mendelian patterns of inheritance that we studied in the previous chapter. Many more traits, however, follow much more complex patterns because they are governed by multiple genes, each contributing a small amount to the trait. How do scientists find which genes are associated with which trait? Molecular biology has greatly changed how scientists go about the search. It has also changed what we mean by the concepts of ‘trait’ or ‘phenotype’ and ‘mutation,’ and has led to many new uses for genetic information.

Chapter Outline

Download the Chapter Outline

Selected Videos

Review Questions

THE PURPOSE of these review quizzes is to guide students in where their knowledge and understanding is strong, where it is weak, and where time should best be spent in studying.

CHAPTER 3:

  • Can you explain the steps involved in transcription, and how the process of transcription differs from that of replication?  Can you explain the steps involved in the process of translation?  Can you draw diagrams showing these steps?  (If you cannot explain these things, or if you are not sure, then you need to reread Section 3.1.)
  • Can you describe various types of mutations and explain how each might be expected to affect the function of the encoded protein? (If you cannot explain these things, or if you are not sure, then you need to reread Section 3.1.)
  • Can you explain how sex is determined in humans and most other animals?  Can you explain how the sex chromosomes usually behave during meiosis?  Can you explain how some abnormal chromosome conditions may arise?  (If you cannot explain these things, or if you are not sure, then you need to reread Section 3.2.)
  • Can you explain the concept of ‘inborn errors of metabolism’?  Can you give some examples?  Can you explain how such conditions helped scientists explain the reasons why certain conditions are dominant and others are recessive?  (If you cannot explain these things, or if you are not sure, then you need to reread Section 3.3.)
  • Can you explain how studies of twins or adopted children can help scientists determine the extent to which a trait is genetically or environmentally controlled? (If you cannot explain these things, or if you are not sure, then you need to reread Section 3.3.)
  • Can you explain how scientists can determine that the gene causing a certain trait is located on a particular chromosome, including how DNA markers are used in this process?  (If you cannot explain these things, or if you are not sure, then you need to reread Section 3.3.)[HDJ1] [ECM2] 
  • Can you explain some reasons why a fetus in utero or a newborn baby should be tested for certain genetic conditions and not others?  Can you give multiple examples of what can be done if certain genetic conditions are found?  Can you give reasoned explanations why certain responses to genetic conditions would not be considered ethical?   (If you cannot explain these things, or if you are not sure, then you need to reread Section 3.4.)

Open Response Study Questions

These questions are designed to assess your understanding of the topics explored in this chapter. You can use these questions in three ways:

Before you start …

Read through the questions before you read the chapter to help prime you to read the text more carefully and strategically. Remember that you are just starting out on your learning journey, so don’t feel disheartened if you don’t know how to answer them yet!

Whilst you read …

As you work through the chapter, have another go at answering the questions to see how you are progressing. You can also answer the questions with the textbook open in front of you, in order to create model answers that can be used to refer back to later.

At the end …

Answer the questions once you have finished reading to see what you have learned. Check your responses against your model answers and use these to identify any gaps in your understanding.

3/14/2022

DEFINITIONS:

In your own words, define ANY TWO of the following terms:

anticodon        autosome         trisomy            euphenics        RFLPs             karyotype

ESSAYS:

Answer any two of the following questions.  Make sure to answer all parts of any question you choose.

1. Explain how the study of alkaptonuria and similar disorders led to an explanation of what makes certain alleles recessive and other alleles dominant.

2. Explain how RFLPs can be used in criminal investigations.

3. Draw a diagram illustrating either the process of transcription or the process of translation (the two steps of gene expression), in as much detail as possible to convey your understanding of these processes.

4. Explain the concept of a chromosomal rearrangement as well as the various subtypes of such rearrangements.

PowerPoint Slides

Download Version A (Illustrations only)
Download Version B (Topic outlines also)

Bibliography

Andertik, M.R.. and M.A. Rothstein. 2001. Privacy and confidentiality of genetic information: what rules for the new science? Ann. Rev. Genomics Human Genetics 2: 401-433.

Beardsley. T. 1997. China syndrome. Scientific American March. 1997: 33-34.

Botstein. D . et al. 1980. Construction of a genetic linkage map in man using restriction fragment polymorphisms. Amer J. Human Genet. 32: 314-331.

Brooker, R.G. 2021. Genetics: Analysis and Principles, 7th ed.  New York: McGraw-Hill.

Brooker, R.G. 2022. Concepts of Genetics, 4th ed.  New York: McGraw-Hill.

Bussey, H. 1996. Chain of being. The Sciences, March/April 1996. pp. 28-33.

Coen, E. 1999. The Art of Genes: How Organisms Make Themselves. New York: Oxford University Press.

Cooper, D.N. 1999. Human Gene Evolution. Oxford: BIOS Scientific Publishers.

Cox, G.A.. et al. 1993. Overexpression of dystrophin in transgenic mdx mice eliminates dystrophic symptoms without toxicity. Nature, 364: 725-729.

D’Alton, M.E., and A.H. DeCherney. 1993. Prenatal diagnosis. New Eng. J. Med.. 328: 114-120.

Davis, B.D.. editor. 1991. The Genetic Revolution. Baltimore: Johns Hopkins Univ. Press.

Edlin, G. 1990. Human Genetics. A Modern Synthesis. Boston: Jones and Bartlett.

Garrod, A.E. 1908. The Croonian lectures: on inborn errors of metabolism. Lancet 174(4427): 1-7.

Gelehrter, T. D. 1990. Principles of Medical Genetics. Baltimore: Williams and Wilkins.

Gillham, N.W. 2001. A life of Sir Francis Galton: From African exploration to the birth of eugenics. Oxford: Oxford University Press.

Goldberg, M., et al.  2021. Genetics: from Genes to Genomes, 7th ed.  New York: McGraw-Hill.

Guggino, W.B. 1999. Cystic fibrosis and the salt controversy. Cell 96:607-610.

Gould. S.J. 1981. The Mismeasure of Man. New York: W. W. Norton.

Gusella, J.F. et al. 1983. A polymorphic DNA marker genetically linked to Huntington’s disease. Nature, 306: 234-238.

Haller, M.H. 1963. Eugenics: Hereditarian Attitudes In American Thought. New Brunswick, NJ: Rutgers University Press.

Hartl, D.L.  2019. Genetics: Analysis of Genes and Genomes, 9th ed.  Sudbury, MA: Jones and Bartlett.

Holtzman, N.A. 1989. Proceed with Caution. Baltimore: Johns Hopkins Press.

Hubbard, R.. and E. Wald. 1993. Exploding the gene myth. Boston: Deacon Press.

Jordan, I.K. 1991. Ethical issues in the genetic study of deafness. In, Genetics of Hearing Impairment; R.J. Ruben, T.R. van de Water, and K.P. Steel, eds., Ann. N.Y Acad. Sci.. 630: 236-239.

Kamin, L.J. 1974. The Science and Politics of IQ. Potomac, MD: L. Erlbaum Associates.

Kerr, A., and T. Shakespeare 2002. Genetic Politics: From Eugenics to Genome. Cheltenham, England: New Clarion Press.

Klug, W.S. et al. 2020.  Concepts of Genetics, 12th ed. London: Pearson.

Levy, H.L. and S. Albers 2000. Genetic screening of newborns. Ann. Rev. Genomics Hunan Genetics 1: 139-177.

Lewin. B. 1999. Genes VII. New York: Oxford University Press.

Lewontin R.C., S. Rose, and L.J. Kamin. 1984. Not in Our Genes. New York: Pantheon Books.

Lusher, J.M., et al. 1993. Recombinant factor VIII for the treatment of previously untreated patients with hemophilia A. New Eng. J. Med.. 328: 453-459.

Maltbie, P.I. 1995. Canary in a coal mine. New Mobility Mar./Apr. 1995: 15.

Marx, J.L. 1989. The cystic fibrosis gene is found. Science, 215: 923-925.

Mukherjee S.  2016.  The Gene:  An Intimate History.  New York:  Scribner’s.

Muller, H.J. 1961. Human evolution by voluntary choice of germ plasm. Science. 134: 643-649.

Muller, H.J. 1965. Means and aims in human genetic development. In T.M. Sonneborn, editor, The Control of Human Heredity and Evolution. New York: Macmillan. pp. 100-122.

Norwitz, E.R. 2013. Noninvasive prenatal testing: the future is now. Rev. Obstet. Gynecol., 6(2): 48-62. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3893900/

Pierce, B.A. 1990. The Family Genetic Sourcebook. New York: Wiley.

Pierce, B.A. 2020. Genetics. A Conceptual Approach, 7th ed. London: Macmillan.

Ridley, M. 1993. A boy or a girl? Is it possible to load the dice? Smithsonian (June, 1993): 113-123.

Rosatelli, M.C. et al. 1992. Molecular screening and fetal diagnosis of beta -thalassemia in the Italian population. Human Genet. 89: 585-589.

Samara, G., et al. 1993. Molecular biology and therapy of disease. Am. J. Surgery. 165: 720-727.

Saxton, M. 1988. Prenatal screening and discriminatory attitudes about disability. Haworth Press, pp. 217-224.

Shreeve, J. 1999. Secrets of the gene. Nat. Geographic Oct 1999: 42-75.

Singer, M., and P. Berg. 1991. Genes and Genomes. A Changing Perspective. Mill Valley, CA: University Science Books.

Snustad, P.J., and M.J. Simmons. 2015. Principles of Genetics, 7th ed.  New York: Wiley.

Stratham, P. 1999. Crick. Watson. and DNA. New York: Anchor Books.

Sudbery, P. 2002. Human Molecular Genetics, 2nd ed. Harlow, England: Pearson Education Limited.

Sutherland, G.R., and R.I. Richards. 1994. Dynamic mutations. American Scientist March-April 1994: 157-163.

Suzuki, D., and P Knudtson. 1989. Genethics: The Clash Between the New Genetics and Human Values. Cambridge. MA: Harvard University Press.

Turnpenny, P.D., and S. Ellard. 2020. Emery’s Elements of Medical Genetics, 16th ed. Amsterdam: Elsevier.

Tudge, C. 2031. The Impact of the Gene: From Mendel’s Peas to Designer Babies. New York: Hill and Wang .

Vogel, E. and A.G. Motulsky. 1986. Human Genetics: Problems and Approaches. 2nd ed. Berlin: Springer Verlag.

Watson. J.D.. et al. 1992. Recombinant DNA. 2nd ed. New York: W.H. Freeman

Watson. J.D. 2000. A Passion for DNA: Genes, Genomes, and Society. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press.

Wilfond, B.S., and N. Frost. 1990. The cystic fibrosis gene: medical and social implications for heterozygote detection. J.A.M.A.. 263:2777-2783.

Chapter 4
Genetic Engineering and Genomics