Biology Assignment on Sex determination

(Designed to be used just prior to introduction of materials on Genetics videodisc)

Developed by Charlotte G. St. Romain
St. Thomas More High School
Lafayette, LA 70507

References:

Howard Hughes publication "From Egg to Adult" (1992). Howard Hughes Medical Inst.,6701 Rockledge Dr., Bethesda, MD 20817. (301)571-0330.

Genetics: "Fundamentals and Frontiers" Laserdisc. Videodiscovery - 1700 Westlake Ave, N, Suite 600, Seattle, WA. (800)-548-3472.

Activity

Read the article "Becoming a Male, Becoming a Female" (pgs 42-45) in the publication From Egg to Adult. Complete this assignment in order to better understand the materials which will be presented on the Genetics laserdisc.

Use complete sentences to answer the questions on a separate sheet of paper.

1. Do all humans begin their lives as the same sex? Give proof of your answer.
2. 1. Explain how we attained the gender we possess (how did we become male or female?)
   2. Is the entire "y" chromosome necessary for sex determination?
3. 1. Sketch separate "x" and "y" chromosomes.
   2. Classify short and long arms
   3. Explain what is meant by the SRY gene. (Label the gene on the "y" chromosome).
4. Locate another reference and define the term "Barr Bodies."
5. 1. Name the hormone that stimulates the development of the male sex organs.
   2. Why aren't female organs produced also?
6. During what stage of prenatal development do sex organs begin to differentiate?
7. By week 16 of prenatal development, how many immature egg cells have been produced?
8. It is interesting to note that almost everything scientists have learned about sex determination has resulted from the study of mutations. From the explanations provided, is the ovary, "the absence of testis?" Explain.
9. How is the SRY considered a switch?
10. (pg 8) Who was Thomas Hunt Morgan? Why is he important to this topic?
11. How many bases are contained on the SRY gene?
12. How long do sperm and eggs last if they do NOT meet?
13. Explain the statement "Fertilization is a relatively rare and complex event".
14. How much time is required for the male gamete's chromosome to mix with the female's egg?
15. How many divisions does the fertilized mass of cells undergo?
16. What did Thomas Cline contribute to the topic of sex determination?

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