Website Search
ID 16250

Specialized chromosomes determine gender.

Description:
Nettie Stevens and Edmund Wilson explain how gender is determined by special chromosomes.
Transcript:
Hello, I'm Nettie Stevens. Dr. Edmund Wilson and I showed that gender is determined by special chromosomes. I did it by looking at cells of meal worms. [MEAL WORM LARVA] The following drawings are adapted from my 1905 paper. Body cells from female worms have 20 chromosomes, all similar in size. As expected, female gametes have a half set of chromosomes (10). [FEMALE BODY CELL GAMETE (EGG)] In male body cells, there are 19 similar chromosomes and one that is much smaller. I found that two types of male gametes are made during meiosis. Some sperm have the small chromosome, and some don't. [MALE BODY CELL GAMETES (SPERM)] I concluded that the "different" chromosome must be responsible for maleness in meal worms. This different chromosome Y and its larger partner X are sex chromosomes. Gender in most species is determined by these sex chromosomes. So, gender is inherited like a Mendelian trait. Human gender is determined this way... Females have two X chromosomes; Males have one X and one Y. Since females can only contribute an X chromosome, males are responsible for the sex of offspring. They can provide either an X chromosome for a female... XX: It's a girl! ....or a Y chromosome for a male. If meiosis and fertilization occur normally, there will be an equal number of males and females. XY: It's a boy!
Keywords:
sex chromosomes, x chromosomes,y chromosomes worm larva, edmund wilson, meal worms, male gametes, nettie stevens, fertilization, body cell, gamete
Downloads:
Creative Commons License This work by Cold Spring Harbor Laboratory is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.

Related content:

16259. Biography 9: Nettie Maria Stevens (1861-1912)
Nettie Maria Stevens independently developed the idea of sex determination by chromosomes.
16260. Biography 9: Edmund Beecher Wilson (1856-1939)
Edmund Beecher Wilson independently developed the idea of sex determination by chromosomes.
16249. Concept 9: Specialized chromosomes determine gender.
Study of meiosis revealed the chromosomal basis of gender.
16261. Problem 9: Specialized chromosomes determine gender.
Try your hand at sex determination.
15520. DNA is organized into 46 chromosomes including sex chromosomes, 3D animation
DNA is organized into 46 chromosomes including sex chromosomes, 3D animation
16246. Biography 8: Theodor Boveri (1862-1915)
Theodor Boveri described the process of meiosis. He also showed that although chromosomes may look similar, they have specific hereditary qualities.
16238. Animation 8: Sex cells have one set of chromosomes; body cells have two.
Theodor Boveri presents chromosomes' role in development.
10536. "Fig. 6. The chromosomes of man"
"Fig. 6. The chromosomes of man"
15606. Y chromosome
The Y chromosome.
16237. Concept 8: Sex cells have one set of chromosomes; body cells have two.
Offspring arise from the union of specialized sex cells — a female egg and a male sperm.
Cold Spring Harbor Laboratory
CSHL HomeAbout CSHLResearchEducationNews & FeaturesCampus & Public EventsCareersGiving