Multicellularity 2

Question 1

what are radial symetrical animals?

Answer 1

1 axis of asymmetry

Question 2

what receptors do WNT bind to?

Answer 2

frizzled receptors

Question 3

What is the Wnt signalling pathway in the absence of Wnt?

Answer 3

• frizzled is unbound
• GSK3beta phosphorylates beta-catenin
• beta-catenin is degraded
• TCF is inactive
• Wnt-responsive genes are off

Question 4

What is the Wnt signalling pathway in the presence of Wnt?

Answer 4

• GSK3beta is bound to the receptor
• beta-catenin is stable and goes to the nucleus
• it binds TCF
• Wnt genes turned on

Question 5

What is non-canonical Wnt signalling

Answer 5

• cell adhesion/cell movement
• cytoskeletal rearrangement

Question 6

Do choanoflagellates have the Wnt pathway?

Answer 6

No

Question 7

What are the radiata?

Answer 7

• Cnidaria
• Placozoa
• Ctenphora
• Porifera

Question 8

Where is Wnt expressed in bilateral organisms?

Answer 8

posterior end

Question 9

Where are Wnt inhibitors expressed in bilateral organisms?

Answer 9

Anterior end

Question 10

How did nerves evolve between sponges and Ctenophora?

Answer 10

theorised that flask cells evolved into nerve cells

Question 11

What is the role of flask cells in sponges?

Answer 11

• may be a precursor to nerves
• contain a junction similar to a synapse
• sponge contain synaptic genes in the flask cells