Normal development and become healthy adults with

normal development and become healthy adults with normal locomotion and other
motor skills (so their muscles work!).
Provide 2 possible explanations for this result:
1.
2.
26. (6 points) Microtubules, and their component protein, tubulin, play several essential
roles during early development.
A. Describe 1 function of these proteins in fully differentiated sperm .
B. Describe 1 function of these proteins in the process of oogenesis .
C. What 1 function do tubulin proteins play in the fertilized embryo before the first cell division ?
27. (4 points) What is a morphogen? In your answer, briefly explain how cells that
secrete a morphogen can relate positional information to an adjacent field of cells.

E-55, Exam 1-2009: Name Page 8 of 9
28. (10 points) Eggs are complex structures with many components that facilitate
interaction with the sperm gamete.
A. What is the zona pellucida, what is it composed of, and why is it necessary for mammalian
fertilization?
B. If you isolate a molecule that is contained within the mammalian zona pellucida, where would
you expect to find this molecule in a sea urchin egg? Briefly explain why.
C. You discover a novel sperm membrane protein in mice, and are interested in determining
whether this protein influences how the sperm interacts with the zona pellucida. Describe one way
that you could gather functiona l evidence for the role of this novel sperm protein in fertilization.
29. (2 points) What is one way to confirm that an antisense knock-down has the
appropriate phenotype for a specific gene you are studying?
30. (2 points) As part of in vitro fertilization (IVF) procedures, it is common practice to
obtain a large number of patient oocytes by ‘superovulation’, which involves stimulating
the patient’s ovaries to produce more than one maturing follicle using synthetic forms of
normal hormones. Name 1 hormone that could be used based on your knowledge of the
hormones that normally trigger this process?

E-55, Exam 1-2009: Name Page 9 of 9
31. (8 points) Fertilization is a multi-step, complex series of events that accomplish
proper gamete joining.
A. Provide the sequence (start to finish) for the following fertilization events in the sea urchin:
1. Activation of egg metabolism, including macromolecular synthesis
2. Acrosome reaction
3. Fusion of cortical granules with plasma membrane of the oocyte
4. DNA replication in the zygote
5. Sperm contacts the oocyte plasma membrane
6. Sperm binds jelly coat
7. Sperm binds vitelline envelope
Sequence__________________________
B. Your lab is testing a collection of phospholipase C inhibitors. At which step(s) (1-7) listed above
would you expect these inhibitors to affect fertilization, and explain why. What would be the
outcome of injecting this inhibitor into a sea urchin egg?
C. Due to funding troubles in your laboratory, you are not able to use chemical indicators to
monitor the outcome of your phospholipase C inhibitors. Name and briefly describe what feature
you could look for under an ordinary compound light microscope that would let you assess
whether eggs treated with your drug behave as expected in the presence of sperm.