Introduction to drosophila

Question 1

What are hox genes and what do they do?

Answer 1

They are zygotic genes

They act along the A-P axis and gives each segment its unique character- wings, leg, antennae

Question 2

What happens to future mesoderm in gastrulation?

Answer 2

It invaginates to form a furrow along the ventral midline

Question 3

What happens to ectodermal cells in gastrulation?

Answer 3

They leave the surface individually and form a layer of prospective neural cells

Question 4

What else does the ectoderm form in gastrulation?

Answer 4

Ectodermal cells are dragged in behind both the anterior and posterior midgut to form the foregut and hindgut

Question 5

What is a germarium?

Answer 5

Where oocyte development begins

It is a mass of stem cells

Question 6

Where is bicoid and oska mRNA localised in the oocyte?

Answer 6

Bicoid- anterior end

Oskar- posterior end

Question 7

What transports bicoid on the mictrotubule and in which direction?

Answer 7

Towards negative end- by dynein

Question 8

What transports oskar on the microtubule and in which direction?

Answer 8

Towards positive end- by kinesin

Question 9

What are the steps in oogenesis?

Answer 9

1. A stem cell in the germarium divides asymetrically- stem cell and a cytoblast
2. Cytoblast undergoes 4 mitotic divisions- 16 cells- cyst
3. One of these cells becomes a oocyte, the other 15- nurse cells
4. The somatic ovarian cells make up a sheath of follicle cells around the nurse cells and oocyte- egg chamber
5. The follicle cells have a key role in patterning the egg’s axes
6. Eventually the oocyte fills the whole egg chamber- mature egg is released from the ovary and laid