Property distribution

During life time of your uncle your sisters( uncle's daughers) can not claim and your uncle can gift entire house to his elder daughter if he like to do so. However if your uncle died and left his property without making any WILL then your two sisters shall have equal share over the property.(excluding the half portion he has already execute a Gift Deed in the name of his elder daughter).

Since it your uncles self acquired property, the younger daughter cannot stake any claim on the said property.

In case the property was not self acquired but ancestral, would the younge daughter be able to claim it while her father is still alive?

yes.. younger daughter has a rightful share in the ancestral property . Since there are three legal heirs, younger daughter is entitled to 1/3 of the share in the entire property. Pl file a partition suit to this effect and you will succeed.