bicd130_06_midtermkey

bicd130_06_midtermkey - BICD 130 - Embryos, Genes, and...

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BICD 130 — Embryos, Genes, and Development Winter 2006 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 (27 pts.)___________________________ Part II (25 pts.)___________________________ Part III (38 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
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I. (27 pts.) 1. (5 pts.) What are the three germ layers generated by gastrulation? How are they arranged relative to each other? Name two tissues or organs that derive from each layer. Ectoderm (outermost), endoderm (innermost), mesoderm (in between)—1 pt for names/1 for positions Ectoderm—skin (epidermis), nervous system (brain/spinal cord/neural tube) Endoderm—lining of digestive, respiratory system, digestive organs Mesoderm—blood, connective tissue, organs like kidney, gonads, etc. 0.5 pt/derivative 2. (4 pts.) What is the defining difference between protostomes and deuterostomes? Name one animal group included in each of these divisions of the animal kingdom. Protostome—mouth first, blastopore becomes the mouth; mollusks/arthropods/worms/Drosophila Deuterostome—mouth second, blastopore becomes anus: echinoderms/vertebrates/mammals/human 1 pt/name, example 3. (4 pts.) Name four constituents of sea urchin egg cortical granules and describe their respective functions during fertilization in this organism. 1 point each Serine protease : digests extracellular linkages between vitelline envelope and cell membrane Mucopolysaccharides : produces osmotic gradient that causes water to fill space between vitelline envelope and cell membrane, causing vitelline envelope to expand and become fertilization envelope Peroxidase : Hardens fertilization envelope (crosslinks tyrosine residues between proteins) Hyalin : Forms a supportive coat around the embryo 4. (4 pts.) Describe how the chick retinotectal map is achieved. Use a diagram to illustrate your answer, and include an account of the specific role(s) of the guidance molecule(s) involved. Diagram (1pt) needs to include retina (with nasal-temporal), nasal side neuron, temporal side neuron, tectum (with AP). Diagram or words: Eph receptor density difference in the axons (1pt). Eph ligand AP gradient in the tectum (1pt). Eph repulsive, less receptors the axons contain, further the neurons project (1pt).
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5. (6 pts.) Distinguish between: (a) a blastocoel, a blastopore, a blastocyst, and a blastomere; (b) compaction and capacitation. 1pt/each
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This note was uploaded on 04/29/2008 for the course BICD 130 taught by Professor Tour during the Fall '07 term at UCSD.

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bicd130_06_midtermkey - BICD 130 - Embryos, Genes, and...

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