REP - L4 - Breaking up symmetry

Question 1

What kind of symmetry do most animals have?

Answer 1

Bilateral.

Question 2

What are Bilateria?

Answer 2

Bilaterally symmetrical animals

Question 3

What does bilateral mean?

Answer 3

Having 2 sides?

Question 4

What do all bilateria have?

Answer 4

Defined dorsal-ventral and anterior-posterior axes.

Question 5

What is cephalisation?

Answer 5

Centralization of neural and sensory organs in the head or anterior region of the body.

Question 6

In drosophyla how are anterior-posterior axes determined?

Answer 6

Maternal effect genes.

Question 7

What’s the point of maternal effect genes?

Answer 7

By-passing transcription - translation into protein can happen straight away.

Question 8

Where in the egg is the RNA including the maternal effect genes deposited?

Answer 8

Nurse cell and oocyte.

Question 9

What genes are responsible for promoting anterior development?

Answer 9

Bicoid and hunchback.

Question 10

What genes are responsible for promoting posterior development?

Answer 10

Caudal and Nanos.

Question 11

How do cells that that receive different concentrations of a morphogen from eachother respond?

Answer 11

Differently.

Question 12

What does AVE stand for?

Answer 12

Anterior visceral Endoderm.

Question 13

What does the anterior visceral endoderm do?

Answer 13

Expresses transcription factors that induce expression of genes (signalling molecules) that tell adjacent tissues to become anterior.

Question 14

What difference is there between the anterior-posterior axis development of the drosophyla and the mouse?

Answer 14

In the drosophyla the anterior posterior axis is established before fertilisation whereas in the mouse it is established long after.

Question 15

Where is the Dorsal protein located in the drosophyla embryo?

Answer 15

Nucleus of ventral region.

Question 16

Why can’t we just look at where the RNA is found when studying body axis genes?

Answer 16

Because the protein location is more important for activity.

Question 17

What are snail and twist?

Answer 17

Transcription factors -

Question 18

Put simply what does dorsol do?

Answer 18

• Activates Snail and Twist in ventral region.
• Activates dpp in dorsal region.

Question 19

What do you get in the absence of dorsal gene?

Answer 19

All dorsal, no ventral.

Question 20

What is ß-catenin?

Answer 20

Gene that codes for a protein that is used for adhering cells.

Question 21

In the xenapus model what do maternal genes do?

Answer 21

Determine D-V Axis.

Question 22

What are some difference between drosophyla and xenopus in regards to dorsal-ventral axis development?

Answer 22

• In drosophyla DV-axis established after 14 cell divisions - established upon fertilisation in xenopus.
• In drosophyla Maternal effect gene throughout embryo - restricted in xenopus.
• In drosophyla regulated by transcription factors - transcription factors and enzymes in xenopus.
• In drosophyla dorsal moves into nucleus on ventral side only - whereas it moves into nucleus on dorsal side in xenopus.