Polarity and Region Identity

Question 1

Ventral nerve cord in drosphila

Answer 1

A bunch of ganglia fused along the midline

Question 2

Gene for red eyes in drosphila

Answer 2

White

Question 3

How does polarization of eggs occur?

Answer 3

Gradients of proteins help polarize the egg

Question 4

Maternal effect genes in drosophila

Answer 4

Bicoid, hunchback, nano, caudal

Question 5

What is the gradient of bicoid and nano in drosophila

Answer 5

Bicoid is high in the anterior end of the egg, while nano is high in the posterior part of the egg

Question 6

How are the gradients of bicoid and nano established?

Answer 6

The egg gets fertilized then bicoid and nano are translated into functional proteins

Question 7

What effect does bicoid have on other maternal effect genes?

Answer 7

• Hunchback: bicoid is a transcriptional activator which makes lots of hunchback according to the bicoid gradient
• Caudal: bicoid actively inhibits caudal to ensure low caudal levels in high hunchback areas

Question 8

What effect does nano have on other maternal effect genes?

Answer 8

• Nano makes lots of caudal
• Nano represses everybody but caudal

Question 9

How are hunchback and caudal gradients created?

Answer 9

Fertilization induces translation of hunchback and caudal which have their mRNA everywhere in the cell, but they grow in a gradient due to the effects of bicoid and nano.