1. A Different World: The Past, Present, and Future of Human Genetics Chapter 15

2. Central Points  We can learn from the eugenics movement of the 1920s  Genetics is moving ahead with many new applications  The future is full of important questions to be decided by society and individuals

3. 15.1 What Can We Learn from the Past?  Eugenicists decided desirable traits  Positive eugenics: encouraged people with those traits to have many children  Decided traits that were not desirable  Negative eugenics: laws passed that forced sterilization and limited immigration

4. Fitter Families

5. Legal Sterilizations  Sterilize criminals, “imbeciles,” and women who were “promiscuous”  Laws upheld by U.S. Supreme Court in Buck v. Bell, challenged sterilization of Carrie Buck  Supreme Court, lead by Justice Oliver Wendell Holmes: the sterilization “is better for all the world…”

6. Eugenics Program of Nazi Germany  U.S. laws as a model, forced sterilization laws  Undesirables: epileptics, physical deformities, alcoholics, Jews, Gypsies, and others  Mercy killing of newborns with genetic diseases  Expanded to include adults in mental institutions, whole groups of people in concentration camps

7. Concentration Camp Killings  Most were Jews, Gypsies, homosexuals, and political opponents of the Nazi regime  Rid a population of “bad genes”: murder  After these killings were revealed, the eugenics movement in U.S. rapidly declined  Fear of misuse of genetics exists today

8. 15.2 Newest Technologies  Stem cell research  Genetic testing  Dog genome  Knockout mice

9. Stem Cell Research Two types:  Embryonic stem cells Form in embryo, in blastocyst Will form all cells of the body, are pluripotent stem cells Reproduce in the lab for many years, form cell line  Adult stem cells Present in the adult body Form only specific types of cells Example: bone marrow produce blood cells

10. Stem Cells

11. Possible Uses of Stem Cells  Cure for degenerative diseases Parkinson’s disease, Alzheimer disease, and MS  Repair spinal cord injuries  Treat burn patients  Until recently, pluripotent stem cells only from human embryos

12. Embryonic Stem Cell Use  Controversy, embryo is destroyed  President George W. Bush: no federal funding for new stem cell lines  In 2007, induced pluripotent cells, or iPCs, using cells from adult skin  May allow tissues and organs to be grown

13. Ethical Questions  Should we use human embryos for research?  Will this research result in anything important?  Who should control scientific experimentation?

14. What Might Happen If…  Who should control scientific research? Politicians? Scientists? General public?  What if stem cell research showed it did: Not do what was expected? Everything that was expected?

15. Genetic Testing and Treatments  BRCA1, BRCA2  Drug treatment possible  Subcutaneous mastectomy  Treatments too drastic  Insurance issues

16. Get the Genetic Test  BRACAnalysis

17. Dog Genome  ID mutant allele of myostatin gene in whippets  Muscle mass in affected dogs doubles  Heterozygous dogs faster than dog with normal myostatin  Homozygous mutant dogs, overmuscled “bully” whippet

18. The “Bully” Whippet

20. Mutant Allele of Myostatin  Found in > a dozen breeds of cattle  “Double muscling” commercially useful property in cattle raised for meat  Young boy with mutation may have future in competitive athletics

21. Cloning Dogs and Cats  In 2002, cloned cat  Dogs more difficult  People willing to pay large amounts of money  December 7, 2005, dog genome sequenced  Breeding may be changing

22. Knockout Mice  Nobel Prize for medicine in 2007  Isolate stem cells from mouse embryos  Target certain genes in mice, turn them off  More than 10,000 or ~half genes in the mouse genome have been knocked out  Example from Chapter 12: behavior of mice changed

23. Knockout Mice

24. Uses of Knockout Mice  Can discover the action gene  Insight into how human diseases progress in tissues and organs over lifetime  Developing and testing new drug therapies  Gene targeting, > 500 mouse models of human disorders

25. 15.3 Future Possibilities  Artificial uterus  Mother at any age  DNA of baby  Closest relative  Clone my daughter

26. Artificial Uterus  In 1999, goat fetus lived 4 of 5 month gestation in an artificial uterus  Clear acrylic tank, 8 quarts of amniotic fluid kept at body temperature  Umbilical cord of goat fetus into two heart–lung machines Supply oxygen and food for fetus and to clean blood of waste products

27. The Artificial Uterus

28. Mother at Any Age  Problem with older eggs is in the cytoplasm  Cause failure of the embryo to divide by mitosis  Nuclear transfer Nucleus from older woman’s egg Into younger woman’s egg that had its nucleus removed

29. Mother of Twins at Almost 57

30. Replacing the Nucleus

31. Nuclear Transfer Experiments  In 1995, China twins conceived, later died but no chromosomal disorders  U.S. successful birth, expect one in 2008  In England, human nucleus into egg of another mammal to study early stages of human embryo  Possibility that resulting child might carry cytoplasm of another species

32. What Might Happen If…  Law to control the age at which a woman could become a mother  Women could freeze own eggs to use later?  A woman with no eggs, no access to sperm, and no uterus wanted a child?  Some people call these embryos “three-parent embryos.” Why?

33. DNA of Baby  Increase development of screening tests  Parental and state testing  Possible to take samples from every newborn and create database

34. Newborn DNA Sampling

35. Closest Relative  Human Genome Project, evolution of the human species written in its genome  Fossil evidence: Homo sapiens originated ~200,000 years ago in Africa, migrated worldwide  Drove Homo neanderthalensis into extinction  ~30,000 years, Neanderthals with Homo sapiens

36. Human Ancestors

37. Neanderthals  Are they direct ancestors of humans? Did they interbreed with Homo sapiens?  Are descendants alive, or did they die off and become extinct?  How do human and Neanderthals genomes compare?

38. DNA from Neanderthal Bones  In 1997, compared mitochondrial DNA sequences  Concluded: Neanderthals distant relative of modern humans  Little or no Neanderthal contribution to the human genome  Did not examine DNA from genes carried in human nuclei

39. Sequence Analysis of Nuclear DNA  Neanderthals and modern humans have genomes > 99.5% identical  Neanderthals not direct relatives of humans  Do not rule out the possibility that Neanderthals and Homo sapiens may have interbred  Neanderthals did not make major contributions to human genome

40. Animation: Human evolution, genus Homo

41. The Ultimate Question  Should humans should be cloned?  Dolly the sheep cloned in the late 1990s  Other animals including cats, dogs, monkeys, and cows  Nuclear transfer or reproductive cloning

42. Fig. 15-12a, p. 247

43. Fig. 15-12b, p. 247

44. Dolly the Sheep

45. Animation: DNA structure and function (how Dolly was created)