Genic balance theory of Calvin Bridges

Calvin Bridges 1926
Genic balance theory of Calvin Bridges

1. Genic Balance theory [email protected] Calvin Bridges 1926

2. Department of Zoology Government College Kasaragod

3. Genic Balance theory [email protected] Calvin Bridges 1926

4. Genic Balance theory [email protected] Calvin Bridges 1926

5. Calvin Bridges

6. This theory was proposed by a Drosophilist Calvin Blackman Bridges in 192 6 . This theory fully explains the sex determination in Drosophila. This theory shows that th e Maleness. Autosomes Femaleness. X chromosomes.

7. Sex determination in Drosophila is quite different from humans Sex in Drosophila is determined by the ratio of number of X chromosomes to that of the number of sets of autosomes

8. Drosophila has eight chromosomes (n = 4)

9. 3 pairs Autosomes

10. Drosophila has th ree pairs of autosomes and one pair of sex chromosomes

11. Sex in Drosophila is determined by the ratio of number of x chromosomes to that of the number of sets of autosomes

12. CONTENTS CONTENTS T he theory of genic balance given by Calvin Bridges ( 1926) 1 states that instead of XY chromosomes, sex is determined by the genic balance or ratio between X-chromosomes and autosome genomes. 2 Enter title 3

13. There are many suggestions regarding the exact molecular mechanism genic b alance system of sex determination i n Drosophila The exact mechanism is still unknown . Studies shown that the X chromosome contains female determining factors Autosomes contains male determining factors Y chromosome in Drosophila does not have any role in sex determination.

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