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Genetics and Genomics

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The Chromosomal Basis for Sex Determination in Fruit Flies

GENES-3PIQS8

Fruit flies, like mammals, ​have XX females and XY males. Unlike mammals, the Y chromosome contains no SRY gene. Instead, flies determine sex by comparing the ratio of sex chromosomes to autosomes. When the number of X chromosomes is equal to the number of any autosome, then the fly is female. If the number of X chromosomes is half of the number of any autosome, then the fly is male. The Y chromosome carries genes involved in the production of sperm.

Give this information, determine the sexes of the following flies. Flies with types of polyploidy can survive.

A fly that contains only one X chromosome and no Y chromosome would be

.

A fly that is XXY would be

.

A fly that is XX but the autosomes are tetraploid would be

.

A fly that is XXXX but the autosomes are tetraploid would be

.

A fly that is XXX but the autosomes are tetraploid would be

.​