ex2_2007_key - Name: _ Student ID:_ Page 1 Zoology 470 -...

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Name: ______________________________________ Student ID:________________________ Page 1 Zoology 470 - Exam #2 – 2007 This exam has 6 pages and a total of 50 points . You will have 90 minutes to complete it. Answer all short answer questions as briefly as possible. Make sure your name and ID number are on all pages. 1. Provide concise definitions for each of the following ( 7 points ) a. Müllerian duct: Duct retained in female but not in male mammals. The Müllerian duct contributes to the formation of the oviduct/fallopian tube. b. blastocoel: A fluid-filled cavity formed during cleavage and prior to gastrulataion. The blastocoel allows for the formation of an internal environment different from the external environment. c. involution: Inward rolling of a sheet of tissue during morphogenesis. d. maskin: Protein involved in regulating translatability of mRNAs, which forms a complex connecting the 3' and 5' regions of mRNAs, thereby effectively "masking" them from the translational machinery. After fertilization, maskin's association with the mRNA is altered, allowing it to be translated. e. myogenic factor: Transcription factor important for muscle differentiation, which when overepxressed causes cells to differentiate as muscle. Examples include MyoD1, myf5, and MRF4. f. Rho: A small (monomeric) G protein that regulates assembly of actomyosin-based contractile structures. Rho is locally activated near the cleavage furrow during cytokinesis in animal cells. g. homeotic gene: Technically, any gene, which when mutated results in a transformation of a body part into another type of body part. Specifically, in Drosophila, gene encoding a homeodomain transcription factor required for proper segmental identity. The 3' to 5' order of homeotic genes on the chromosome corresponds to their anterior to posterior domain of action along the body axis. 2. Complete the following table referring to cleavage patterns in early embryos of various animals ( 5 points ) Animal Yolk Distribution Completeness of Cleavage Orientation of cleavages Drosophila (fruit fly) centrolecithal meroblastic Not applicable Monkey (mammal) isolecithal holoblastic rotational Starfish (an echinoderm) isolecithal holoblastic Chicken (bird) telolecithal meroblastic discoidal Snail (a gastropod mollusk) isolecithal holoblastic spiral 3. Circle true (T) or false (F) for each of the following ( 7 points )
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Name: ______________________________________ Student ID:________________________ Page 2 T Humans, like other chordates, are deuterostomes F A weak mutation in the mouse pax-6 gene would be expected to result in loss of posterior structures, since the fly homologue is involved in patterning posterior segments of the embryo T The Wolffian duct is normally retained in male mammals F Proteins can act as transcriptional regulators or translational regulators, but not both T Germ band extension in Drosophila occurs via convergent extension F
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This note was uploaded on 08/08/2008 for the course ZOO 470 taught by Professor Hardin during the Spring '08 term at Wisconsin.

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ex2_2007_key - Name: _ Student ID:_ Page 1 Zoology 470 -...

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