- Homeotic selector genes are responsible for the specification of Drosophila body parts. Which one of the following identities would you expect if the ultrabithorax gene is deleted?
(1) The third thoracic segment is transformed to another second thoracic segment and a fly with four wings.
(2) The third thoracic segment develops halteres.
(3) The second thoracic segment loses wings.
(4) The first and second thoracic segments fuse and wings are formed on the third thoracic segment.The Ultrabithorax (Ubx) gene is a crucial homeotic selector gene in Drosophila responsible for specifying the identity of the third thoracic segment (T3). This gene plays a vital role in suppressing wing development in T3 and promoting the formation of halteres — small structures used for balancing during flight.
Deletion or mutation of the Ultrabithorax gene removes this regulatory influence. As a result, the T3 segment loses its specific identity and, instead, adopts the identity of the second thoracic segment (T2). Since T2 normally develops wings, the transformed T3 develops an additional pair of wings in place of halteres.
This homeotic transformation is a hallmark example showcasing how Hox genes control segmental identity and morphology by switching developmental programs. The loss of Ubx function thus yields flies with four wings, with the third thoracic segment being transformed into a duplicated second thoracic segment.
Therefore, the expected identity change upon Ultrabithorax gene deletion is:
(1) The third thoracic segment is transformed to another second thoracic segment and a fly with four wings.
Answer: (1) The third thoracic segment is transformed to another second thoracic segment and a fly with four wings
17 Comments
Neelam Sharma
November 10, 2025The third thoracic segment is transformed to another second thoracic segment and a fly with four wings.
Deepika Sheoran
November 10, 2025The third thoracic segment is transformed to another second thoracic segment and a fly with four wings.
Sonam Saini
November 10, 2025The third thoracic segment is transformed to another second thoracic segment and a fly with four wings.
Sneha .......
November 11, 2025The third thoracic segment is transformed to another second thoracic segment and fly with four wings
Kajal
November 12, 2025Option 1
Bhawna Choudhary
November 12, 2025Option 1 is correct
Kirti Agarwal
November 12, 2025Statement A
Rishu
November 12, 2025The third thoracic segment is transformed to another second thoracic segment and a fly with four wings
Sonal Nagar
November 13, 2025Option 1st
Priya khandal
November 13, 2025Option 1st is correct
Mohd juber Ali
November 13, 2025Mutantion in ultrabithorex t3 turn in to t2 means develop pair of wings except develop of halteres .
a fly with four wings
Neha Yadav
November 14, 2025The third thoracic segment is transformed to another second thoracic segment and a fly with four wings
Santosh Saini
November 16, 2025The third thoracic segment is transformed to another second thoracic segment and a fly with four wings
Manisha choudhary
November 17, 2025The third thoracic segment is transformed to another second thoracic segment and a fly with four wings.
Sakshi Kanwar
November 18, 2025The third thoracic segment is transformed to another second thoracic segment and a fly with four wings
Muskan Yadav
November 20, 2025The third thoracic segment is transformed to another second thoracic segment and a fly with four wings.
Kavita Choudhary
November 21, 2025The third thorax sagment transformed to another second thorax sagment and fly with four wings