ANSWERS Process of Science (11.10)

How Can the “Head” Gene Be Regulated to Alter Development?

Lab Notebook

Presence of Anterior Structures Experiment None Anterior Middle Posterior

Anterior cytoplasm extract from normal fly added to: Anterior of bicoid fly X Middle of bicoid fly X Posterior of bicoid fly X Anterior of normal fly X Posterior of normal fly X X

Extract of plant added to: Anterior of normal fly X Posterior of normal fly X

Extract of plant and anterior cytoplasm added to: Anterior of bicoid fly X Middle of bicoid fly X Posterior of bicoid fly X

Questions

1. Why do you think this mutation rarely shows up in fly populations?

The offspring of females with the mutation fail to develop into normal adult flies. Therefore, they cannot reproduce and pass on the mutation. The appearance of this characteristic is solely due to mutation in the female fly and not a result of inheritance. ______Campbell/Reece/Taylor/Simon Biology: Concepts & Connections, Sixth Edition, © Pearson Education, Inc., publishing as Benjamin Cummings 2. Based on the plant extract experiments, come up with a hypothesis explaining the way the plant extract produces the shown effects on the normal fly.

It is difficult to isolate one particular mechanism of action from this experiment. The plant compound could either prevent the production of bicoid mRNA in the nurse cells, prevent the translation of the bicoid mRNA in the embryo or prevent the action of the bicoid protein in the embryo.

3. Now that you have this additional data, come up with the most plausible hypothesis or hypotheses for the chemical's action.

The plant extract is either preventing the translation of the bicoid mRNA in the embryo or preventing the action of the bicoid protein in the embryo. Other experimentation would have to be performed to identify the specific mechanism of action.

______Campbell/Reece/Taylor/Simon Biology: Concepts & Connections, Sixth Edition, © Pearson Education, Inc., publishing as Benjamin Cummings