Cross-Dressing or Crossing-Over: Sex Testing of Women Athletes

1. Cross-Dressing or Crossing-Over: Sex Testing of Women Athletes Maureen Knabb, Department of Biology, West Chester University, and Joan Sharp, Biological Sciences, Simon Fraser University Modified by Penny Dunning, EHS

2. Santhi’s Story http://www.ibnlive.com/videos/28851/how-are-athletes-gender-tested.html

3. Santhi’s Story Santhi Soundararajan won the silver medal in the 800-meter race at the 2006 Asian Games in Doha, Qatar.

4. Santhi’s Story Following her silver medal performance, her sex was officially questioned.

5. 18 Dec. 2006: “Indian athlete Santhi Soundararajan fails gender test” • Top Indian woman athlete Santhi Soundararajan, who won a silver medal at a recent regional championship, has failed a gender test, according to official reports.

6. 18 Dec. 2006: “Indian athlete Santhi Soundararajan fails gender test” • Sports writer KP Mohan said that a team of doctors, including a gynecologist, endocrinologist and psychologist, normally examines athletes and puts them through physical and clinical examinations during a gender test.

7. 18 Dec. 2006: “Indian athlete Santhi Soundararajan fails gender test” • Santhi Soundararajan's test was done soon after Soundararajan came in second in the women's 800m race on 9 December, but it is not clear how she failed the test at the Asian Games in Doha.

8. How do you know if someone is male or female? • Talk to the person next to you and identify at least 5 characteristics to distinguish males from females.

9. How is sex determined in humans? • Anatomy: Primary and secondary sexual characteristics - genitalia, body hair, pelvis, etc. • Physiology: Function and interaction of the sex organs including concentrations of sex hormones such as estrogen, progesterone, and testosterone.

10. CQ1: Imagine you are a member of the committee assigned to determine whether Santhi is female. Here are possible results of the initial tests (we don’t know the real results): Female genitalia: Yes Breasts and pubic hair: Yes Regular menstrual cycle: Never From this information, you conclude that Santhi is: A: Male B: Female

11. CQ1: Imagine you are a member of the committee assigned to determine whether Santhi is female. Here are possible results of the initial tests (we don’t know the real results): Female genitalia: Yes Breasts and pubic hair: Yes Regular menstrual cycle: Never From this information, you conclude that Santhi is: B: Female

12. Is there another way that sex is characterized in humans? • Chromosomes: • Females possess two X chromosomes in each of their cells, • Males have one X and one Y chromosome.

13. Is there another way that sex is characterized in humans? • How do you visualize chromosomes? • Chromosomes are only visible when preparing for nuclear division. • Chromosomes must be stained.

14. Karyotype In diploid organisms, chromosomes come in pairs. How many? 0 (picture of chromosomes in a cell) Human Karyotype

15. CQ2: A karyotype was performed on a different athlete. Here are the results: From these results, the athlete is: A: MaleB: Female

16. CQ2: A karyotype was performed on an athlete. Here are the results: From these results, the athlete is: Male

17. CQ3: So if Santhi is a normal female, her karyotype would be: A: XX B: XY C: YY D: XXY

18. CQ3: So if Santhi is a normal female, her karyotype would be: A: XX

19. 0 The Fate of Genetic Material During Sexual Reproduction • You contain genetic material from both your Mom and Dad. • You have 46 chromosomes, and so do (will) your children. • How does this happen?

20. SEX Mom 46 chromosomes Dad (2n = diploid) Egg 23 chromosomes Sperm (1n = haploid) Zygote (fusion) 46 chromosomes again!

21. Haploid and Diploid Chromosomes Haploid with one chromatid Haploid with two chromatids Diploid with one chromatid Diploid with two chromatids

22. CQ4: Assume that this is one of Santhi’s chromosomes. This chromosome is composed of two chromatids joined by a centromere. Are the following statements TRUE or FALSE?

23. These chromatids make up a diploid chromosome. False

24. B. The cell that contains these sister chromatids must be diploid. False

25. C. The sister chromatids were formed by replicating a single chromatid. True

26. D. The sister chromatids were joined by fertilization, bringing together a maternal and paternal chromatid. False

27. 0 Meiosis • Purpose of meiosis: • in animals, to produce gametes with just half the parents’ genetic material. Gametes are _____(haploid/diploid). Haploid

28. 0 Meiosis • Mechanism: Only one of each pair of homologous chromosomes gets into each gamete. • The happy ending: Gametes from the two parents get to fuse, restoring the original number of chromosomes in the fertilized egg (zygote).

29. 0 Stages of Meiosis • Meiosis (in animals) produces 4 haploid cells from 1 diploid cell. • At the end of the first division (Meiosis I) the 2 cells are already haploid. • The second division (Meiosis II) splits the 2 sister (identical, replicated DNA) chromatids to 1 chromatid. Animation: http://www.johnkyrk.com/meiosis.html

30. 0 CQ5: Which one is true after Meiosis I? A: Four cells have been produced. B:The cells are haploid. C: The DNA will be replicated once more. D: The cells are ready to perform as gametes. E: Each chromosome consists of a single strand of DNA.

31. 0 CQ5: Which one is true after Meiosis I? B: The cells are haploid.

32. 0 CQ6: During Meiosis II: A: Homologous chromosomes separate. B: The DNA is replicated. C: Gametes fuse. D: Sister chromatids separate. E: All of the above.

33. 0 CQ6: During Meiosis II: D: Sister chromatids separate.

34. Sources of Genetic Variability in Meiosis Independent Assortment • Each pair of homologous chromosomes lines up at Metaphase I plate.

35. Sources of Genetic Variability in Meiosis Independent Assortment • There is a 50:50 chance that a daughter cell will get one or the other copy of the chromosome. Animation: http://wps.prenhall.com/wps/media/objects/487/498795/CDA10_2/CDA10_2b/CDA10_2b.htm

36. CQ7: How many possible combinations of maternal chromosomes are possible in a human ovum due to independent assortment during meiosis? A: 23 combinations. B: 46 combinations. C: 232 = 529 combinations. D: 223 = ~ 8 million combinations.

37. CQ7: How many possible combinations of maternal chromosomes are possible in a human ovum due to independent assortment during meiosis? D: 223 = ~ 8 million combinations.

38. Sex Determination • In mammals, males have one X and one Y chromosome. • In males, half the daughter cells formed by Meiosis I get an X chromosome and half get a Y chromosome. • Following Meiosis II and sperm differentiation, half the sperm are X-bearing and half are Y-bearing.

39. Sex Determination • In mammals, males have one X and one Y chromosome. • A special cell division called Meiosis will form gametes (sperm) • Half their sperm are X-bearing and half are Y-bearing.

40. Sex Determination • In mammals, females have two X chromosomes. • A special cell division called Meiosis will form gametes (eggs) • All eggs are are X-bearing.

41. How is Sex Determined in Humans? • Sex is determined by the sex chromosome carried by the sperm. • What percent of offspring will be boys and what percent will be girls? sperm X Y X XX XY egg XX XY X girls boys

42. CQ8: Could Santhi have an XX karyotype and be male? A: No, an XX individual is always female. B: Yes, this is common. C: Yes, if a male-determining control gene is carried on one of her X chromosomes.

43. CQ8: Could Santhi have an XX karyotype and be male? We will see…

44. Sources of Genetic Variability in Meiosis Crossing Over During Meiosis • When homologous chromosomes pair during meiosis, non-sister chromatids exchange homologous portions.

45. Sources of Genetic Variability in Meiosis Crossing Over During Meiosis • A chiasma forms between the non-sister chromatids at the point of crossing over.

46. Sources of Genetic Variability in Meiosis Crossing Over During Meiosis • Following crossing over, the chromatids are recombinant, combining paternal and maternal genes.

47. Crossing Over • Crossing overcan occur anywhere along the autosomes. • In males, the sex chromosomes (X and Y chromosomes) normally cross over only at their tips if at all.

48. CQ9: During crossover, all of the following happen EXCEPT: A: The homologous chromosomes line up in pairs. B: The homologous chromosomes swap pieces with their adjacent partners. C: Crossing over decreases the genetic variability in the gametes. D: Each chromatid is unique after it has crossed over.

49. CQ9: During crossover, all of the following happen EXCEPT: C: Crossing over decreases the genetic variability in the gametes. (Crossing over actually INCREASES the genetic variability in the gamets)

50. How is Sex Characterized in Humans? • Anatomy –What they look like, genitals • Physiology – hormones • Chromosomes- XX or XY • But there is a 4th answer: Genes Specific genes determine whether an embryo will develop as a male or female.