BICD 130 wi07 midterm - BICD 130 Embryos Genes and...

Info icon This preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
BICD 130 — Embryos, Genes, and Development Winter 2007 Midterm Exam (Four parts, 100 points total) ______________________________________________________ Please PRINT your name here Please write your answers in ink . Requests for regrades will not be considered for exams done in pencil. Part I (15 pts.)___________________________ Part II (54 pts.)___________________________ Part III (21 pts.)__________________________ Part IV (10 pts.)___________________________ "It is not birth, marriage, or death, but gastrulation, which is truly the most important time in your life." --Lewis Wolpert
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
I. (15 pts.) The diagrams above show three stages of chick embryo development: gastrulation (top), early neurulation (middle), and late neurulation (bottom). Fill in the 15 blank lines with the names of the indicated structures or tissues. Be careful to give the name that is appropriate to the stage of development shown.
Image of page 2
1. Hensen’s Node 2. Primitive groove/streak 3. Epiblast, Ectoderm 4. Blastocoel 5. Hypoblast 6. Endoderm 7. Mesodermal cells/mesenchyme 8. Ectoderm 9. Neural groove/neural plate (MHP cells ok, primitive groove IS NOT) 10. Endoderm 11. Notochord 12. Mesoderm 13. Dorsal ectoderm/presumptive epidermis 14. Neural tube 15. Neural crest cells
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
II. (54 pts.) 1. (7 pts.) In the nematode worm C. elegans , netrin protein encoded by the unc-6 gene acts as an axon guidance molecule. Netrin expressed in ventral cells is attractive to the axons of sensory neurons (which project ventrally from laterally located cell bodies) but repulsive to the axons of motor neurons (which project dorsally from ventrally located cell bodies). Draw diagrams illustrating the sensory and motor axon patterns in (a) a wild-type worm; (b) an unc-6 mutant; (c) a mutant for unc-40 , which encodes a component of an attractive netrin receptor; (d) a mutant for unc-5 , which encodes a component of a repulsive netrin receptor. -1 point for no orientation; No credit if no labeling of axons a) 1 point b) 2 points unc-6 mutant Sensory Motor No migration of either Neuron Neuron neuron type c) 2 points unc-40 mutant d) 2 points unc-5 mutant No migration of No migration of sensory neurons motor neurons 2. (10 pts.) Describe in detail how, after the completion of neurulation, two signaling centers pattern the neural tube in the D/V axis. Include in your answer the original sources of the two signals, the signaling molecules involved, and the effects of the signals on the neural tube. Use diagrams to illustrate your answer.
Image of page 4
3. (8 pts.) Describe two mechanisms for the prevention of polyspermy in sea urchin fertilization.
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern