Question

Explain sex determination in Drosophila.

Answer 1

Drosophila flies have both X and Y chromosomes, as well as autosomes. Unlike humans, the Y chromosome does not confer maleness; rather, it encodes genes necessary for making sperm. Sex is instead determined by the ratio of X chromosomes to autosomes. ... Three major genes are involved in determinationof Drosophila sex.

Answer 2

Answer:

Sex determination in Drosophila, like in humans, is of XX-XY type.  The males are heterogametic ( two different types of gametes) in nature and it is the male gamete that determines the sex of the progeny or offsprings.

Explanation:

In dioecious ( the sexes are separate, or, the male and female reproductive organs are in separate individuals ) diploidic ( having two sets of chromosomes, one from each parent ) organisms, two systems of sex chromosomal determination of sex  have been recognized:

1. Heterogametic males ( the male has two different gametes whereas the female gamete is one );

2. Heterogametic females ( the female has two different gametes whereas the male gamete is one ).

The Drosophila males are heterogametic. The females have two homomorphic ( homo-same; morphic-form) X chromosomes in their cells ( hence, referred to as XX ). The females being homogametic produce only one type of gamete (egg), each containing an X chromosome.  The males possess one X chromosome and one Y chromosome ( hence, referred to as XY ). The males having two heteromorphic sex chromosomes produce two kinds of gametes ( sperms ): half having an X chromosome and half having a Y chromosome. The sex of the embryo is decided by the sperm. An egg fertilized by a sperm with an X chromosome produces a female whereas if fertilized by a sperm with a Y chromosome produces a male.