Question

In Drosophila, it is well established that bicoid specifies anterior-posterior axis determination. Predict the effect on the embryo if…
A) Wild-type Bicoid mRNA is injected into the posterior section of the egg.
B) A bicoid transgene expresses wild-type bicoid mRNA and protein at 4 times the normal level.
C) A mutant fly with a defective bicoid binding site is isolated.

Answer 1

Answer:

A. In case if Bicoid RNA is administered into the posterior section of the egg, it will result in a second anterior end of the fly.  

B. The adequate activity of bicoid RNA is important as a transcriptional activator. The expression of bicoid RNA more in comparison to normal results in the production of bigger anterior domain than usual.  

C. Bicoid is essential for the determination and formation of the thorax and the head of the embryo. In the case of a bicoid mutant fly, the composition of the head and the thorax gets transformed into the abdomen that produces an embryo with posterior composition on both the terminals.