LESSON III:
HERMAPHORDITISM IN HUMANS I
To Address NYS Standard:
4 (The continuity of life is sustained through reproduction and development.)
Behavioural Objective:
The students will be able to understand the difference between gender and biological sex, and will be able to thus place in context human hermaphrodites. The students will also be able to understand how sex is determined, and how and/or gender are really not as black and white as they may seem.
Explanation of Lesson Plan:
This lesson is about the physiology of hermaphroditism, but is also about how society comes to view sex, gender, and those who do not fit into either “box” that has been created. The lesson is as much about how society views those of indeterminate sex as much as it is about why they do.
Hook: (3 minutes)
“You have asked me for more information on hermaphrodites, and today we are going to go a little deeper into the subject, in order to fully understand the situation. We will need to investigate the development and determination of sex in humans, and only then will you be able to truly understand how, if at all, hermaphrodites differ from other humans. I do require, however, that we use respectful and proper language and terminology at all times. You will be immediately sent out of the room if you use any terms that I deem inappropriate or disrespectful.”
Test of Prior learning: (5 minutes)
1. Remember what words hermaphrodite comes from? (Hermes and Aphrodite – messenger of the gods, and god of love, whose son was Hermaphroditus, who ended up being fused with a nymph to posses characteristics of both sexes.)
2. Why wouldn’t a hermaphrodite want to self-fertilize?
New Learning: (30 minutes)
1. We need to first investigate how sex is determined in humans, and then we can see how hermaphrodites can come to be.
2. Sex, in humans, is determined by the chromosomes. Males are XY, while females are XX. You get one sex chromosome from your mother, one from your father. Which you get is random. What, then, are you chances of ending up male or female?
3. The Y chromosome is very small, as compared to the X and the autosomes. There is one gene on the Y chromosome that makes humans male.
4. This gene is called SRY, for Sex-determining Region Y. It codes for a protein, a transcription factor, which is a Testes-determining Factor (TDF). This protein initiates the production of testes from the gonad tissue.
5. The testes then begin to produce testosterone, which begins the development of the rest of the body as male.
6. This gene, and ONLY this gene, produces a male. There are a number of ways that this can go awry, however.
7. Klinefelter Syndrome affects males, and is characterized by having a XXY, XXXY, or XXXXY. These males may develop female body hair patterns, have small penises or testicles, sterility, and gynecomastia.
8. XYY Males are very rare. Why do you think? Where does the extra Y come from? These males were once thought to be more aggressive or taller, based on studies conducted in prisons, but this was found to be untrue.
9. There are females with only one X, called Turner Syndrome, with a chromosome count of XO. These females are shorter, sterile, and may not develop female secondary sex characteristics.
10. Multiple X chromosomes (XXX, XXXX, XXXXX) result in females who often have learning disabilities, are sterile, and taller.
11. There are a number of chromosomal mutations that can cause the “wrong” sex to be expressed, as well.
12. Androgen Insensitivity Syndrome (AIS) results when testosterone receptors on cells are defective. Thus, the genotype is XY, but the phenotype is female. This causes some debate at athletic events, etc. Testosterone is produced, but it has no effect on the cells of the body.
13. A person may have the genotype XX, but have a male phenotype, as a result of a chromosomal translocation. This happens when a small slice of the Y chromosome breaks off, and attaches to an X. Thus, the SRY gene is active, but on the wrong ‘some!
14. All these items blur the lines between gender and sex. We classically define gender and sex as synonyms, but in modern times, they have come to take on different meanings.
15. Sex is usually in reference to the biology of the situation, which, as you can see, isn’t as clear cut as you might think.
16. Gender is usually how our society views a person. This discordance between sex and gender is cause for much concern for many people.
17. Often, some of these mutations that we have discussed, or others that we will not, will cause indeterminate genitalia at birth.
18. Babies are not allowed to be released from the hospital without a sex on the birth certificate. So, doctors are often forced to perform operations, or “assign” a gender. Why do you think that this may cause some problems later in life?
Test of New Learning: (5 minutes)
1. Compare our system of bipartisan politics to the duality of gender in the united states.
2. How does this system help or hurt society? Individuals?
Assignment: