Cross-Dressing or Crossing-Over?
Sex Testing of Women Athletes
Department of Biology
West Chester University of Pennsylvania
Department of Biological Sciences
Simon Fraser University
In this “clicker case,” students learn about sex determination, meiosis, and chromosomal “crossing over” through the story of Santhi Soundararajan, an athlete from Kathakkurichi, India, who was stripped of a medal at the 2006 Asian Games after failing to pass a sex test. The case is called a clicker case because it combines the use of student personal response systems (clickers) with case teaching methods and formats. The case itself is a PowerPoint presentation (~2 MB) shown in class that is punctuated by questions students respond to using their clickers. It can be adapted for use without these technologies. Developed for an introductory biology class for both majors and non-majors, the case could also be used in an anatomy and physiology course or an endocrinology course.
- Explain the basis of sex determination in mammals.
- Describe the sources of variation in daughter cells produced by meiosis.
- Understand the role of the SRY gene in the determination of a human embryo as male.
- Explain how human sex reversal (XX/SRY+ male; XY/SRY- female) may take place.
KeywordsCrossing-over; gametogenesis; gender testing; sex testing; meiosis; cell division; karyotype; sex determination; sex reversal; SRY gene; Santhi Soundararajan
Topical AreasLegal issues, Social issues
Educational LevelUndergraduate lower division
Type / MethodsClicker, Interrupted, Dilemma/Decision
Subject HeadingsBiology (General) | Cell Biology | Physiology | Sports Science |
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Teaching notes are intended to help teachers select and adopt a case. They typically include a summary of the case, teaching objectives, information about the intended audience, details about how the case may be taught, and a list of references and resources.
The following Supplemental(s) are recommended for use in association with this case study.Click and Learn Activity: Gender Testing of Athletes
Lecture: Deciphering the Language of Sex
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The following video(s) are recommended for use in association with this case study.
- Meiosis (Animation)
Meiosis, the form of cell division unique to egg and sperm production, sets the stage for sex determination by creating sperm that carry either an X or a Y sex chromosome. But what is it about the X or Y that determines sex? The animation presented in this video connects meiosis and sex determination. Running time: 5:53 min. Produced by: HHMI BioInteractive.
- The Y Chromosome (Animation)
The Y chromosome has been likened to a hall of mirrors because its sequence contains many sections that appear to be palindromes. These palindromes provide a clue to some interesting events that may have occurred during the course of the chromosome's evolution. Running time: 2:46 min. Produced by: HHMI BioInteractive.