MM - DROSOPHILA GAP GENE, BCD, HB AND NANOS GRADIENTS

Question 1

What maternally produced mRNA is found in the oocyte? and what is it anchored to?

Answer 1

1. Bicoid mRNA is anchored to the anterior
2. Nanos mRNA is anchored to the posterior
3. Bicoid mRNA is found throughout the oocyte
4. Hunchback mRNA is found throughout the oocyte

Question 2

After translation what does Bicoid Protein do?

Answer 2

Bicoid protein is a transcription factor for zygotic Hunchback and turns it on.

Question 3

After translation what does Nanos protein do?

Answer 3

Nanos protein acts as an inhibitor for the translation of Hunchback mRNA

Question 4

What happens due to the positioning of mRNA on the A-P axis?

Answer 4

Due to the positions of the mRNA’s, a protein gradient is formed after fertilisation

Question 5

What are the positions of the proteins?

Answer 5

1. Bicoid = A - P gradient
2. Hunchback = A - P gradient
3. Nanos = P - A gradient
4. Caudal = P - A gradient

Question 6

How is Hunchback switched on?

Answer 6

Hb is switched on via Bicoid protein in a concentration specific manner.
So below the threshold limit, no zygotic Hb mRNA is transcribed.

Question 7

How is a boundary produced along the embryo?

Answer 7

The threshold limit and the transcriptional inhibition of Hb (via nanos) causes a sharp boundary around halfway of the embryo.