The Meaning of Sex: Genes and Gender

Lecture 4 – Sexual Evolution: From X to Y

by David C. Page, MD

  1.  1.  Start of Lecture 4
  2.  2.  Introduction by Grants Program Director Dr. Dennis Liu
  3.  3.  Introductory interview with Dr. David Page
  4.  4.  Description of study measuring testosterone levels of participating students
  5.  5.  Testosterone study: Student predictions
  6.  6.  Testosterone study: Interpretations
  7.  7.  What does the Y chromosome do?
  8.  8.  Cartoon map of Y-chromosome genes
  9.  9.  Real map of the Y chromosome: Non-recombining region is passed down clonally
  10. 10.  Map of the Y chromosome with its three classes of genes
  11. 11.  Overview of 300 million years of Y-chromosome evolution
  12. 12.  Synopsis of the animation on Y-chromosome evolution
  13. 13.  Animation: SRY gene evolves and an autosome becomes a Y chromosome
  14. 14.  Animation: Y chromosome degrades over time
  15. 15.  Animation: Y chromosome also gains new genes
  16. 16.  Student question: Why doesn't inversion occur on other chromosomes?
  17. 17.  Student question: How does temperature determine the sex of a reptile?
  18. 18.  Student question: Why doesn't the X chromosome undergo inversions?
  19. 19.  Deletions on the Y chromosome are a leading cause of male infertility
  20. 20.  Video: Sperm motility in normal- and low-sperm-count samples
  21. 21.  Some men with low sperm counts are missing part of the Y chromosome
  22. 22.  Review of spermatogenesis
  23. 23.  Seminiferous tubules of men with out the DAZ gene
  24. 24.  Intracytoplasmic sperm injection (ICSI) as a remedy for low sperm count
  25. 25.  Video: ICSI procedure
  26. 26.  Problem with ICSI and male babies
  27. 27.  Ethical issues with ICSI
  28. 28.  Student question: Does ICSI always work?
  29. 29.  Student question: Does my dog have more genes on its Y chromosome than my brother has?
  30. 30.  Student question: In ICSI, how is the embryo returned to the uterus?
  31. 31.  Student question: Will evolution lead to the complete destruction of the Y chromosome?
  32. 32.  Student question: Will Y-chromosome deletions always be transmitted?
  33. 33.  Student question: Could we program the sex of a would-be child?
  34. 34.  Student question: What is considered a normal sperm count?
  35. 35.  Student question: Why do flies have the Y chromosome but reptiles don't?
  36. 36.  Student question: Could we reinsert DAZ genes in sperm with DAZ deletions?
  37. 37.  Closing remarks by HHMI President Dr. Thomas Cech

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