efmb-chpt-5-6

Readings: Chapters 5-6 from “Endless Forms Most Beautiful”

With ideas you encounter in the reading, develop three discussion questions that integrate, explore, and extend what we have learned so far in the course about the mechanisms and principles of development.  Access the link to the discussion question submission on the course schedule.  If they are well thought out and complete they will earn you part of your credit for the homework assignment that day.  We will select a couple of these to discuss in class (without associating names with who submitted them).

Reading Questions--bring your answers to these questions, as you will be responsible for answering one of them in class.  You will not turn these answers in.

1. What is the “dark matter” in the genome? What is its function?

2. What is a genetic switch physically and what is its function? Give an example of a genetic switch we have talked about in class. 

3. How do switches convert spatial information of toolkit protein expression into different domains of gene expression?  To illustrate the idea use figure 5.2 and predict what would happen to the stripe of gene expression if repressor B was not present in the embryo. 

4. How do switches convert spatial information of toolkit protein expression into different domains of gene expression?  To illustrate the idea use figure 5.2 and predict what would happen to the stripe of gene expression if repressor B was present in the embryo but the DNA sequence bound by B was changed so that it is no longer bound by B.

5. Where are the operating instructions for the toolkit of development? Describe the logic/experimental results that support your answer. 

6. What developmental toolkit genes were in the ancestors of the animals seen in the Cambrian?  Describe the logic/experimental results that support your answer. 

7. What changes in the toolkit are thought to have caused the Cambrian Explosion?

8. How might shifting Hox gene expression patterns (Fig 6.7) lead to differences in appendages in arthropods? 

9. Did the emergence of complex arthropods from simpler lobopodian-like ancestors result from the acquisition of new Hox genes (an increase in Hox gene number)? What analysis supports this idea?