Question

How does the Bicoid protein provide positional information along the anterior-posterior axis of the fly embryo? a. It is present at high concentration at the anterior end and low concentration at the posterior end. b. Different forms of Bicoid protein exist at different locations along the anterior-posterior axis. c. It is present at high concentration at the posterior end and high concentration at the anterior end. d. Bicoid protein is present at a uniform concentration along the anterior-posterior axis.

Answer 1

Answer:

a. It is present at high concentration at the anterior end and low concentration at the posterior end.

Explanation:

One of the ways to define the anterior-posterior axis in Drosophila is by the products of the Bicoid and Nanos genes. The mRNA from the bicoid gene is transcribed by nurse cells. The bicoid mRNA is deposited in the unfertilized egg near its anterior pole. Therefore, the bicoid gene product serves as the anterior morphogen. The bicoid mRNA is translated after fertilization. The Bicoid proteins are present in higher concentrations at the anterior end and diffuse through the cell to create a concentration gradient from the anterior to the posterior end.